紫花苜蓿和黄花苜蓿生长特性及其与秋眠性的关系研究
|
摘要
苜蓿(Medicago sativa L.)是世界上最重要并且种植最广的豆科牧草,在我国畜牧业发展中占有重要地位。但是,缺乏越冬性(winter hardiness)一直是限制苜蓿利用的主要因素。秋眠性(fall dormancy)以其与越冬性的密切相关关系,作为预测越冬性的重要组分被广泛应用。越冬性选育重要的一点就是选育的种质必须还要有较高的产量,苜蓿品种越冬性的选育必然也同时伴随着对低秋眠性的筛选。因此,目前苜蓿的秋眠特性对品种或者种质越冬性的评估和育种筛选具有不可替代的作用。本文以不同秋眠性苜蓿品种为主要对象,研究了种子对不同温度的发芽响应,比较了不同品种的发芽特征和积温模型参数以及与秋眠级数的关系;研究了不同生长阶段的苜蓿幼苗的抗冻性并计算得到不同品种幼苗期的半致死温度;研究了本地区测定苜蓿品种秋眠性的适宜刈割时间;同时结合本地紫花苜蓿品种和黄花苜蓿(Medicago falcata)材料研究了野外不同播期下苜蓿幼苗的形态特征以及与品种秋眠性的关系;探讨了不同紫花苜蓿品种和黄花苜蓿材料建植当年根系和根颈的生长特性。此外还在不同埋深和光照条件下研究了紫花苜蓿和黄花苜蓿等豆科牧草幼苗的出土和生长情况。应用积温模型对不同苜蓿品种种子的发芽特性与秋眠级数关系的研究结果指出,最
终发芽百分数与品种间秋眠级数没有相关性,而发芽速率、最低温度和积温与品种秋眠级数之间均存在显著或者极显著的强烈相关关系,特别是积温(r=-0.99,p<0.001)。随品种秋眠性的增强,发芽速率增加,发芽所需最低温度上升,所需积温减少。根据这些指标与秋眠的强烈相关关系,建立了相应的秋眠级数预测方程,可以根据不同温度下的发芽速度和积温模型参数对未知品种或者种质的秋眠级数进行简便有效的预测。
对不同年龄阶段苜蓿幼苗抗冻性的检验结果说明,不同苜蓿品种和幼苗不同生长阶段之间抗冻性有很大差异。幼苗生长阶段和冷冻温度之间存在极显著的交互作用,苜蓿幼苗不同生长阶段之间抗冻性的不同很大程度上是取决于胁迫的温度。在高于半致死温度时,幼苗抗冻性基本随年龄增加而增加,而在低于半致死温度时,幼苗的抗冻性是随年龄增加而减少的。-9℃下几个生长阶段的幼苗品种间抗冻性均有显著差异,能够较好的区分品种间的不同。实验中计算得到的三个不同秋眠级数苜蓿幼苗的半致死温度在-6.79到-8.1℃,品种间的相对排序和各自的秋眠级数是一致的。得到了预测苜蓿品种在给定的冷冻温度下幼苗致死率的方程,可用于推测该品种或者拥有类似秋眠级数的苜蓿品种幼苗在本实验的环境条件下不同冷冻温度的死亡率。
通过探讨不同苜蓿品种不同生长阶段幼苗的生长特性对不同播期的响应以及与秋眠级数的关系,本研究发现秋季播种的四周龄幼苗的生长特性与秋眠级数的相关性最大。秋季播种的四周龄幼苗的株高、生物量、子叶节长、真叶柄长、真叶长和真叶宽等指标与秋眠级数显著相关,相关性要高于其他播期的,并且相关系数均超过0.9。由这些形态指标建立的回归方程,可以在一定程度上对秋眠级数进行预测。对实验中15个紫花苜蓿品种进行聚类分析的结果显示,根据秋季播种的幼苗生长性状,可以将紫花苜蓿品种划分为秋眠,半秋眠和不秋眠三个类群,与它们的秋眠级数所指示的类型基本一致,说明通过秋季生长的幼苗的性状特征,可以有效区分三种秋眠类型的植株。
在不同刈割时间下,对苜蓿品种间再生高度差异的比较说明,本地区在8月25日左右对苜蓿进行刈割,25天或者更长时间后进行再生高度的测定,可以较好的区分不同品种的秋眠性,在密植的条件下进行秋眠级数的测定也同样可行。本实验中锡盟黄花苜蓿的秋季再生高度体现了黄花苜蓿材料的极秋眠特性。
对不同苜蓿品种根系和根颈的生长性状进行的研究,结果表明:建植当年不同苜蓿品种根系和根颈的生长性状有很大差异。公农2号、CW402和金皇后的根系发育能力和根颈特征都要强于其他品种,体现在主根直径、主根干重、主根长度、根系总重、侧根数、根颈直径、分枝和芽数等指标都高于其他品种;所有苜蓿品种主根直径和根系生物量均随土层深度从上至下呈递减趋势。建植当年的苜蓿根系主要分布在40cm土层内,所有品种的侧根均发生在0～30 cm土层,30 cm以下极少发生侧根。本研究中锡盟黄花苜蓿材料主根偏细,根系干重较低,侧根数目也不多,根颈入土深度较浅,体现了黄花苜蓿生长速度较慢,在播种当年根系不能充分发育。而本地紫花苜蓿品种公农2号根系和根颈的大部分性状都好于其他品种,验证了根系和根颈性状特点与品种适应性的关系。本研究中各根系和根颈性状与秋眠级数的相关性均不显著,但是主根直径、根系总重、主根干重、主根长度、侧根条数、根颈直径、根颈入土深度和基部总芽数间均呈显著或者极显著正相关关系。
在不同埋深和光照条件下对苜蓿等五种豆科牧草的幼苗出土和生长进行了研究,结果表明1和2cm的埋深为五种豆科牧草的最适埋深,此后,随埋深的增加,幼苗出土率降低,出土时间增加,幼苗大小也减少。遮阴可以促进豆科牧草的出土,但是对后期的幼苗生长不利。大种子物种幼苗的生长情况通常要好于小种子物种的。兴安胡枝子、紫花苜蓿和黄花苜蓿在深埋或者遮阴的条件下幼苗出土率较高,生长也较好。
本文通过对不同紫花苜蓿品种和黄花苜蓿材料生物学性状的多方面研究,找到了指示苜蓿品种秋眠性和适应性的一些相关性状,通过这些性状得到的预测方程,可以对秋眠级数进行快速准确的检验,为预测未知品种或者种质的秋眠性和进行抗寒越冬选择性育种时对秋眠性的筛选,提供了有用的信息,并可以有效减少秋眠检验时间和缩短育种周期。
Alfalfa (Medicago sativa L.) is the most important and widely cultivated forage legume in the world, and it plays an important role on livestock husbandry in China. However, lack of winter hardiness is a major limitation to the reliable use of alfalfa. Fall dormancy has traditionally been the primary component used to predict winter hardiness in alfalfa because of its association with winter survival. The important point of selection for winter hardiness is that the germplasm selected must also be high yielding, thus winter hardiness and less fall dormancy are being selected concurrently. Fall dormancy is playing an irreplaceable role on evaluation of winter hardiness in alfalfa varieties and lines and also in selection in alfalfa breeding. Alfalfa varieties with contrasting fall dormancy class were use in this research, to test the responses of seed germination to constant temperature, and compare the germination traits and parameters of thermal time model of different varieties and test the relationships between these traits and fall dormancy class. Freezing tolerance of alfalfa seedlings with different growth stage was studied and the freezing temperature that kills 50% of seedlings (LT50) for each variety of alfalfa was evaluated as well. Local alfalfa varieties and Medicago falcata germplasm were used with other alfalfa varieties with contrasting fall dormancy class to study the growth traits of seedling with different growth stages under different sowing dates, and the correlated relationships between the growth traits and fall dormancy were tested as well. Research on the appropriate defoliating time of the determination for fall dormancy class of alfalfa varieties was conducted. The root and crown traits of different alfalfa varieties in the establishment year were also studied. In addition, experiment was conducted to study the emergence and seedling growth of five forage legume species at various burial depth and two light levels.
The results of alfalfa seed germination response to temperature indicated that there was no significant liner regression relationship between the final germination percentage and fall dormancy class. However, there were significant or extremely significant liner regression relationship between the germination rate, Tb,θand fall dormancy class, especially forθ(r=-0.99,p<0.00). Germination rate and base temperature decreased with the fall dormancy class of alfalfa varieties whileθincreased with the fall dormancy class. The high correlated between fall dormancy and germination rate, Tb andθindicated that measuring fall dormancy class of alfalfa through the equations using those traits will make the evaluation of FD of the experimental lines and varieties much more convenient, and also shorten the screening and breeding cycle.
Experiments were conducted in the growth chamber to determine freezing tolerance of 3 alfalfa varieties at four growth stages. Tolerance to freezing temperature varies among varieties and seedling growth stages. There was a significant interaction between seedling growth stage and freezing temperature, the differences of freezing tolerance among seedling growth stages were mainly determined by freezing temperature. Seedling freezing tolerance increased with seedling age when the freezing temperature was higher than LT50. However, freezing tolerance decreased with seedling age when the freezing temperature was lower than LT50. -9℃was suitable to distinguish different varieties, because the differences in freezing tolerance of seedling of all growth stages of different varieties were significant. The LT50 were -6.8 to -8.1℃for alfalfa varieties, the relative ranking among varieties was the same with their fall dormancy class. The prediction equation for each variety have potential for predicting seedling stand loss at given freezing temperatures.
According to the response of alfalfa seedling morphological traits and biomass accumulation to different sowing date and its relationship with fall dormancy class, when sowing in autumn, the correlations between growth traits of 4 weeks old seedlings and fall dormancy class of varieties were the greatest. Seedling height, seedling biomass, unifoliate internode length, unifoliate leaf petiole length, unifoliate leaf length and wide of alfalfa seedlings sowing in autumn and fall dormancy classes of varieties were significantly highly correlated, and the correlated coefficient were all higher than 0.9. The regression equations according to these traits could predict the fall dormancy to a certain extent. The results of hierarchical clustering indicated that, according to the seedling growth traits sowing in autumn, alfalfa varieties could be classified to three groups: fall dormant group, semi-fall dormant group and non-dormant group, which was similar with that predicting by fall dormancy class. Plants of the three fall dormant types could be distinguished by the seedling growth traits sowing in autumn.
The comparation about the differences among alfalfa varieties under different defoliating time indicated that defoliationg on August 25 and determining the regrowth height after 25days or more could discriminate varieties with different fall dormancy. And the result under solid planted condition is also reliable. The determined fall dormancy class of Ximeng was 1 in this study, which indicated the extremly fall dormancy of M.falcata.
There were significantly differences between root and crown traits of different alfalfa varieties in the establishment year. GongNong No.2, CW402 and Golden Empress had better root and crown development abilities, for their taproot diameter, taproot mass, taproot length, total root mass, lateral root number, crown diameter, crown branch number and crown bud number were higher than other varieties. The taproot diameter and root biomass of all alfalfa varieties were decreased from soil surface layer to deep layer. Distribution of alfalfa root systems in the establishment year were mainly in the underground 40 cm. Lateral root of all varieties which grew from the taproot were in underground 0～30 cm. Few lateral roots were found below 30 cm. In this study, Medicago falcata from XiMeng had thinner taproot, lower total root mass, fewer lateral root and shallower crown depth, which indicated that the growth rate of M. falcata was slow and it developed incompletely in the establishment year. However, most characteristics of local alfalfa variety GongNong No.2 were better than those of other cultivars, which meant that root and crown traits were related to variety adaption. Correlation analysis indicated that there was no significant relationship between fall dormancy and root or crown traits. However, there were significantly or extremely significantly correlation between taproot diameter, total root mass, taproot mass, taproot length, lateral root number, crown diameter, crown depth and basal bud number.
The results of the seedling emergence and structure of five forage legumes at five planting depths and two light levels indicated that the optimal planting depth for all the forage legumes in this study was 1 to 2 cm. Increasing depth lowered and slowed seedling emergence, and reduced the seedling size. Shade condition improved seedling emergence but was unfavorable for seedling growth. Seedling emergence and growth were usually better for species with bigger seed than those with small seed. M. falcata, M. suaveolens and M. sativa had higher percent emergence and better growth from deeper depth or under shade condition.
In conclusion, we found some important traits that are valuable on predicting fall dormancy and adaption of alfalfa varieties through the studies on alfalfa biological traits under different environment conditions. The prediction equations of fall dormancy class were obtained according to these traits. It is a quick and effective way on evaluation of fall dormancy of alfalfa varieties and lines and also can shorten the selection of winter hardiness in alfalfa breeding.
终发芽百分数与品种间秋眠级数没有相关性,而发芽速率、最低温度和积温与品种秋眠级数之间均存在显著或者极显著的强烈相关关系,特别是积温(r=-0.99,p<0.001)。随品种秋眠性的增强,发芽速率增加,发芽所需最低温度上升,所需积温减少。根据这些指标与秋眠的强烈相关关系,建立了相应的秋眠级数预测方程,可以根据不同温度下的发芽速度和积温模型参数对未知品种或者种质的秋眠级数进行简便有效的预测。
对不同年龄阶段苜蓿幼苗抗冻性的检验结果说明,不同苜蓿品种和幼苗不同生长阶段之间抗冻性有很大差异。幼苗生长阶段和冷冻温度之间存在极显著的交互作用,苜蓿幼苗不同生长阶段之间抗冻性的不同很大程度上是取决于胁迫的温度。在高于半致死温度时,幼苗抗冻性基本随年龄增加而增加,而在低于半致死温度时,幼苗的抗冻性是随年龄增加而减少的。-9℃下几个生长阶段的幼苗品种间抗冻性均有显著差异,能够较好的区分品种间的不同。实验中计算得到的三个不同秋眠级数苜蓿幼苗的半致死温度在-6.79到-8.1℃,品种间的相对排序和各自的秋眠级数是一致的。得到了预测苜蓿品种在给定的冷冻温度下幼苗致死率的方程,可用于推测该品种或者拥有类似秋眠级数的苜蓿品种幼苗在本实验的环境条件下不同冷冻温度的死亡率。
通过探讨不同苜蓿品种不同生长阶段幼苗的生长特性对不同播期的响应以及与秋眠级数的关系,本研究发现秋季播种的四周龄幼苗的生长特性与秋眠级数的相关性最大。秋季播种的四周龄幼苗的株高、生物量、子叶节长、真叶柄长、真叶长和真叶宽等指标与秋眠级数显著相关,相关性要高于其他播期的,并且相关系数均超过0.9。由这些形态指标建立的回归方程,可以在一定程度上对秋眠级数进行预测。对实验中15个紫花苜蓿品种进行聚类分析的结果显示,根据秋季播种的幼苗生长性状,可以将紫花苜蓿品种划分为秋眠,半秋眠和不秋眠三个类群,与它们的秋眠级数所指示的类型基本一致,说明通过秋季生长的幼苗的性状特征,可以有效区分三种秋眠类型的植株。
在不同刈割时间下,对苜蓿品种间再生高度差异的比较说明,本地区在8月25日左右对苜蓿进行刈割,25天或者更长时间后进行再生高度的测定,可以较好的区分不同品种的秋眠性,在密植的条件下进行秋眠级数的测定也同样可行。本实验中锡盟黄花苜蓿的秋季再生高度体现了黄花苜蓿材料的极秋眠特性。
对不同苜蓿品种根系和根颈的生长性状进行的研究,结果表明:建植当年不同苜蓿品种根系和根颈的生长性状有很大差异。公农2号、CW402和金皇后的根系发育能力和根颈特征都要强于其他品种,体现在主根直径、主根干重、主根长度、根系总重、侧根数、根颈直径、分枝和芽数等指标都高于其他品种;所有苜蓿品种主根直径和根系生物量均随土层深度从上至下呈递减趋势。建植当年的苜蓿根系主要分布在40cm土层内,所有品种的侧根均发生在0～30 cm土层,30 cm以下极少发生侧根。本研究中锡盟黄花苜蓿材料主根偏细,根系干重较低,侧根数目也不多,根颈入土深度较浅,体现了黄花苜蓿生长速度较慢,在播种当年根系不能充分发育。而本地紫花苜蓿品种公农2号根系和根颈的大部分性状都好于其他品种,验证了根系和根颈性状特点与品种适应性的关系。本研究中各根系和根颈性状与秋眠级数的相关性均不显著,但是主根直径、根系总重、主根干重、主根长度、侧根条数、根颈直径、根颈入土深度和基部总芽数间均呈显著或者极显著正相关关系。
在不同埋深和光照条件下对苜蓿等五种豆科牧草的幼苗出土和生长进行了研究,结果表明1和2cm的埋深为五种豆科牧草的最适埋深,此后,随埋深的增加,幼苗出土率降低,出土时间增加,幼苗大小也减少。遮阴可以促进豆科牧草的出土,但是对后期的幼苗生长不利。大种子物种幼苗的生长情况通常要好于小种子物种的。兴安胡枝子、紫花苜蓿和黄花苜蓿在深埋或者遮阴的条件下幼苗出土率较高,生长也较好。
本文通过对不同紫花苜蓿品种和黄花苜蓿材料生物学性状的多方面研究,找到了指示苜蓿品种秋眠性和适应性的一些相关性状,通过这些性状得到的预测方程,可以对秋眠级数进行快速准确的检验,为预测未知品种或者种质的秋眠性和进行抗寒越冬选择性育种时对秋眠性的筛选,提供了有用的信息,并可以有效减少秋眠检验时间和缩短育种周期。
Alfalfa (Medicago sativa L.) is the most important and widely cultivated forage legume in the world, and it plays an important role on livestock husbandry in China. However, lack of winter hardiness is a major limitation to the reliable use of alfalfa. Fall dormancy has traditionally been the primary component used to predict winter hardiness in alfalfa because of its association with winter survival. The important point of selection for winter hardiness is that the germplasm selected must also be high yielding, thus winter hardiness and less fall dormancy are being selected concurrently. Fall dormancy is playing an irreplaceable role on evaluation of winter hardiness in alfalfa varieties and lines and also in selection in alfalfa breeding. Alfalfa varieties with contrasting fall dormancy class were use in this research, to test the responses of seed germination to constant temperature, and compare the germination traits and parameters of thermal time model of different varieties and test the relationships between these traits and fall dormancy class. Freezing tolerance of alfalfa seedlings with different growth stage was studied and the freezing temperature that kills 50% of seedlings (LT50) for each variety of alfalfa was evaluated as well. Local alfalfa varieties and Medicago falcata germplasm were used with other alfalfa varieties with contrasting fall dormancy class to study the growth traits of seedling with different growth stages under different sowing dates, and the correlated relationships between the growth traits and fall dormancy were tested as well. Research on the appropriate defoliating time of the determination for fall dormancy class of alfalfa varieties was conducted. The root and crown traits of different alfalfa varieties in the establishment year were also studied. In addition, experiment was conducted to study the emergence and seedling growth of five forage legume species at various burial depth and two light levels.
The results of alfalfa seed germination response to temperature indicated that there was no significant liner regression relationship between the final germination percentage and fall dormancy class. However, there were significant or extremely significant liner regression relationship between the germination rate, Tb,θand fall dormancy class, especially forθ(r=-0.99,p<0.00). Germination rate and base temperature decreased with the fall dormancy class of alfalfa varieties whileθincreased with the fall dormancy class. The high correlated between fall dormancy and germination rate, Tb andθindicated that measuring fall dormancy class of alfalfa through the equations using those traits will make the evaluation of FD of the experimental lines and varieties much more convenient, and also shorten the screening and breeding cycle.
Experiments were conducted in the growth chamber to determine freezing tolerance of 3 alfalfa varieties at four growth stages. Tolerance to freezing temperature varies among varieties and seedling growth stages. There was a significant interaction between seedling growth stage and freezing temperature, the differences of freezing tolerance among seedling growth stages were mainly determined by freezing temperature. Seedling freezing tolerance increased with seedling age when the freezing temperature was higher than LT50. However, freezing tolerance decreased with seedling age when the freezing temperature was lower than LT50. -9℃was suitable to distinguish different varieties, because the differences in freezing tolerance of seedling of all growth stages of different varieties were significant. The LT50 were -6.8 to -8.1℃for alfalfa varieties, the relative ranking among varieties was the same with their fall dormancy class. The prediction equation for each variety have potential for predicting seedling stand loss at given freezing temperatures.
According to the response of alfalfa seedling morphological traits and biomass accumulation to different sowing date and its relationship with fall dormancy class, when sowing in autumn, the correlations between growth traits of 4 weeks old seedlings and fall dormancy class of varieties were the greatest. Seedling height, seedling biomass, unifoliate internode length, unifoliate leaf petiole length, unifoliate leaf length and wide of alfalfa seedlings sowing in autumn and fall dormancy classes of varieties were significantly highly correlated, and the correlated coefficient were all higher than 0.9. The regression equations according to these traits could predict the fall dormancy to a certain extent. The results of hierarchical clustering indicated that, according to the seedling growth traits sowing in autumn, alfalfa varieties could be classified to three groups: fall dormant group, semi-fall dormant group and non-dormant group, which was similar with that predicting by fall dormancy class. Plants of the three fall dormant types could be distinguished by the seedling growth traits sowing in autumn.
The comparation about the differences among alfalfa varieties under different defoliating time indicated that defoliationg on August 25 and determining the regrowth height after 25days or more could discriminate varieties with different fall dormancy. And the result under solid planted condition is also reliable. The determined fall dormancy class of Ximeng was 1 in this study, which indicated the extremly fall dormancy of M.falcata.
There were significantly differences between root and crown traits of different alfalfa varieties in the establishment year. GongNong No.2, CW402 and Golden Empress had better root and crown development abilities, for their taproot diameter, taproot mass, taproot length, total root mass, lateral root number, crown diameter, crown branch number and crown bud number were higher than other varieties. The taproot diameter and root biomass of all alfalfa varieties were decreased from soil surface layer to deep layer. Distribution of alfalfa root systems in the establishment year were mainly in the underground 40 cm. Lateral root of all varieties which grew from the taproot were in underground 0～30 cm. Few lateral roots were found below 30 cm. In this study, Medicago falcata from XiMeng had thinner taproot, lower total root mass, fewer lateral root and shallower crown depth, which indicated that the growth rate of M. falcata was slow and it developed incompletely in the establishment year. However, most characteristics of local alfalfa variety GongNong No.2 were better than those of other cultivars, which meant that root and crown traits were related to variety adaption. Correlation analysis indicated that there was no significant relationship between fall dormancy and root or crown traits. However, there were significantly or extremely significantly correlation between taproot diameter, total root mass, taproot mass, taproot length, lateral root number, crown diameter, crown depth and basal bud number.
The results of the seedling emergence and structure of five forage legumes at five planting depths and two light levels indicated that the optimal planting depth for all the forage legumes in this study was 1 to 2 cm. Increasing depth lowered and slowed seedling emergence, and reduced the seedling size. Shade condition improved seedling emergence but was unfavorable for seedling growth. Seedling emergence and growth were usually better for species with bigger seed than those with small seed. M. falcata, M. suaveolens and M. sativa had higher percent emergence and better growth from deeper depth or under shade condition.
In conclusion, we found some important traits that are valuable on predicting fall dormancy and adaption of alfalfa varieties through the studies on alfalfa biological traits under different environment conditions. The prediction equations of fall dormancy class were obtained according to these traits. It is a quick and effective way on evaluation of fall dormancy of alfalfa varieties and lines and also can shorten the selection of winter hardiness in alfalfa breeding.
引文
[1] Sledge M, Kochert J. Shifts in pest resistance, fall dormancy, and yield in 12-, 24-, and 120-parent grazing tolerant synthetics derived from CUF 101 alfalfa[J]. Crop Science, 2003, 43(5): 1736-1740.
[2] Russelle M P. Alfalfa[J]. American Scientist, 2001, 89: 252-261.
[3]耿华珠.中国苜蓿[M].中国农业出版社, 1995.
[4]全国畜牧总站.中国草业统计(2010年)[G]. 2011.
[5] Castonguay Y, Laberge S, Brummer E C, et al. Alfalfa winter hardiness: A research retrospective and integrated perspective[J]. Advances in Agronomy, 2006, 90: 203-265.
[6]洪绂曾.苜蓿科学[M].中国农业出版社, 2009.
[7]朱飞雪.黄花苜蓿不同品系的遗传多样性及其快速繁殖研究[D].甘肃农业大学, 2008.
[8] Riday H, Brummer E C. Forage yield heterosis in alfalfa[J]. Crop Science, 2002, 42(3): 716-723.
[9] Berdahl J, Wilton A, Frank A. Survival and agronomic performance of 25 alfalfa cultivars and strains interseeded into rangeland[J]. Journal of Range Management, 1989, 42(4): 312-316.
[10] Mortenson M C, Schuman G E, Ingram L J. Carbon sequestration in rangelands interseeded with yellow-flowering alfalfa (Medicago sativa ssp. falcata)[J]. Environmental Management, 2004, 33 (suppl.1): 475-481.
[11] Mortenson M C, Schuman G E, Ingram L J, et al. Forage production and quality of a mixed-grass rangeland interseeded with Medicago sativa ssp. falcata[J]. Rangeland Ecology and Management, 2005, 58(5): 505-513.
[12] Riday H B, Moore E C, Kenneth J. Heterosis of forage quality in alfalfa[J]. Crop Science, 2002, 42(4): 1088-1093.
[13] Waldron L. First generation crosses between two alfalfa species[J]. Journal of American Socity Agronomy, 1920, 12: 133-143.
[14] Riday H, Brummer E C. Heterosis in a broad range of alfalfa germplasm[J]. Crop Science, 2005, 45(1): 8-17.
[15] Brummer E C. Capturing heterosis in forage crop cultivar development[J]. Crop Science, 1999, 39(4): 943-954.
[16] Sriwatanapongse S, Wilsie C. Intra- and inter-variety crosses of Medicago sativa L. and Medicago falcata[J]. Crop Science, 1968, 8(4): 465-466.
[17]王俊杰.中国黄花苜蓿野生种质资源研究[D].内蒙古农业大学, 2008.
[18] Haagenson D, Cunningham S, Volenec J. Root physiology of less fall dormant, winter hardy alfalfa selections[J]. Crop Science, 2003, 43(4): 1441-1447.
[19] Wang C, Ma B, Yan X, et al. Yields of alfalfa varieties with different fall-dormancy levels in a temperate environment[J]. Agronomy Journal, 2009, 101(5): 1147-1152.
[20] Castonguay Y, Michaud R, Nadeau P, et al. An indoor screening method for improvement of freezing tolerance in alfalfa[J]. Crop Science, 2009, 49(3): 809-818.
[21] McKenzie J, Paquin R, Duke S. Cold and heat tolerance, In“Alfalfa and alfalfa improvement”(A. A. Hanson, D. K. Barnes, and R. R. Hill, Jr., Eds.).[M]. Madison Wisconsin, USA.1988. 259-302.
[22] Belanger G R, Castonguay P, Bootsma Y, et al. Climate change and winter survival of perennial forage crops in eastern canada[J]. Agronomy Journal, 2002, 94(5): 1120.
[23] Brouwer D J, Duke S H, Osborn T C. Mapping genetic factors associated with winter hardiness, fall growth, and freezing injury in autotetraploid alfalfa[J]. Crop Science, 2000, 40(5): 1387-1396.
[24] Sheaffer C, Barnes D, Warnes D, et al. Seeding-year cutting affects winter survival and its association with fall growth score in alfalfa[J]. Crop Science, 1992, 32(1): 225-231.
[25] Barnes D. Minnesota fall dormancy and its relationship to winter injury[C]. 1991: 14-16.
[26] Nittler L W, Gibbs G H. The response of alfalfa varieties to photoperiod, color of light and temperature[J]. Agronomy Journal, 1959, 51(12): 727-730.
[27] Sprague M, Fuelleman R. Measurements of recovery after cutting and fall dormancy of varieties and strains of alfalfa, Medicago sativa[J]. Agronomy Journal, 1941, 33(5): 437.
[28] Brummer E C, Shah M M, Luth D. Reexamining the relationship between fall dormancy and winter hardiness in alfalfa[J]. Crop Science, 2000, 40(4): 971-977.
[29] Cunningham S, Volenec J, Teuber J. Winter hardiness, root physiology, and gene expression in successive fall dormancy selections from 'Mesilla' and 'CUF 101' alfalfa[J]. Crop Science, 2001, 41(4): 1091.
[30] Teuber L, Taggard K, Gibbs L, et al. Check cultivars, locations, and management of fall dormancy evaluation[C]. In: North American Alfalfa Improvement Conference Committee, Beltsville. MD, 1998.25.
[31] Larson K L, Smith D. Association of various morphological characters and seed germination with the winter hardiness of alfalfa[J]. Crop Science, 1963, 3(3): 234-237.
[32] Larson K L, Smith D. Reliability of various plant constituents and artificial freezing methods in determining winterhardiness of alfalfa1[J]. Crop Science, 1964, 4(4): 413-417.
[33] Schwab P, Barnes D, Sheaffer C. The relationship between field winter injury and fall growth score for 251 alfalfa cultivars[J]. Crop Science, 1996, 36(2): 418-426.
[34] Smith D. Winter injury and the survival of forage plants[J]. Herbage Abstracts, 1964, 34: 203-209.
[35] Brouwer D, Duke S, Osborn T. Comparison of seedlings and cuttings for evaluating winter hardiness in alfalfa[J]. Crop Science, 1998, 38(6): 1704-1707.
[36] Kohel R J, Davis R L. The inheritance of cold resistance and its relation to fall growth in F2 and BC1 generation of alfalfa[J]. Agronomy Journal, 1960, 52(4): 234-237.
[37] Smith D. Association of fall growth habit and winter survival in alfalfa[J]. Canadian Journal of Plant Science, 1961, 41(2): 244-251.
[38] Busbice T, Wilsie C. Fall growth, winter hardiness, recovery after cutting and wilt resistance in F2 progenies of vernal dupuits alfalfa crosses[J]. Crop Science, 1965, 5(5): 429-432.
[39] Daday H. Genetic relationship between cold hardiness and growth at low temperature in medicago sativa[J]. Heredity, 1964, 19(2): 173-179.
[40] Weishaar M A B, Volenec E C, Moore J J, et al. Improving winter hardiness in nondormant alfalfa germplasm[J]. Crop Science, 2005, 45(1): 60.
[41] Haagenson D, Joern S, Volenec B. Autumn defoliation effects on alfalfa winter survival, root physiology, and gene expression[J]. Crop Science, 2003, 43(4): 1340.
[42] Knipe B, Reisen P, McCaslin M. The relationship between fall dormancy and stand persistence in alfalfa varieties[C]. In: 1998 California Alfalfa Symposium, 1998. 203-208.
[43] Teuber L R, taggard K L, Gibbs G H, et al. Fall dormancy, The United States Department of Agriculture, Editor. 1998.
[44] Barnes D, Bingham E, Murphy R, et al. Alfalfa germplasm in the United States: Genetic vulnerability, use, and maintenance[J]. USDA Technology Bulletin,1977, 1571:21.
[45] Lehman W F, Marble V L, Erwin D C, et al. Nondormant alfalfa, past, present, and future[C]. In: California Alfalfa Symp. Process, Minneapolis, MN, 1987: Coop Ext University of California, Davis: 29-38.
[46] Barnes D, Smith D, Stucker R, et al. Fall dormancy in alfalfa: A valuable predictive tool[C]. In: 26th Alfalfa Improvement Conference, Brookings, SD, 1978: 1-34.
[47] Johnson L, Marquez-Ortiz J, Lamb J, et al. Root morphology of alfalfa plant introductions and cultivars[J]. Crop Science, 1998, 38(2): 497-502.
[48] Perry M C, Mcintosh M, Wiebold W, et al. Genetic analysis of cold hardiness and dormancy in alfalfa[J]. Genome, 1987, 29(1): 144-149.
[49]何云,刘圈炜,王成章,等.苜蓿秋眠性研究进展[J].草业科学, 2005, 22(11): 25-30.
[50] Barnes D K, Smith D M, Teuber L R, et al. Fall dormancy[C]. In: 3rd ed. North American Alfalfa Improvement Conference, 1991: A1-A2.
[51] Reisen P M, Gurrier C G, Melton B A. Measurement of fall dormancy in solid-and space planted plots[Z]. 1990.
[52] Schnieder M. Relationship between unifoliate internode length and fall dormancy in alfalfa[D]. Davis,CA: University of California, 1984.
[53] Kallenbach R, Roberts C, Teuber L, et al. Estimation of fall dormancy in alfalfa by near infrared reflectance spectroscopy[J]. Crop Science, 2001, 41(3): 774-777.
[54]王红柳,岳征文,卢欣石.基于近红外光谱技术与支持向量机的苜蓿秋眠类型测定研究[J].光谱学与光谱分析, 2011, 31(6): 1510-1513.
[55] Ariss J J, Vandemark G J. Assessment of genetic diversity among nondormant and semidormant alfalfa populations using sequence-related amplified polymorphisms[J]. Crop Science, 2007, 47(6): 2274-2284.
[56] Yu K, Pauls K. Rapid estimation of genetic relatedness among heterogeneous populations of alfalfa by random amplification of bulked genomic DNA samples[J]. TAG Theoretical and Applied Genetics, 1993, 86(6): 788-794.
[57] Welsh J, McClelland M. Fingerprinting genomes using pcr with arbitrary primers[J]. Nucleic Acids Research, 1990, 18(24): 7213-7218.
[58] Badaruddin M, Meyer D. Factors modifying frost tolerance of legume species[J]. Crop Science, 2001, 41(1): 1911-1916.
[59] Meyer D W, and M. Badaruddin. Frost tolerance fo ten seedling legume species at four growth stages[J]. Crop Science, 2001, 41(6): 1838-1842.
[60] Heichel G, Henjum K. Fall dormancy response of alfalfa investigated with reciprocal cleft grafts[J]. Crop Science, 1990, 30(5): 1123-1127.
[61] Cloutier Y, Pelletier L, Michaud R. Development of a test for freezing tolerance in young alfalfa seedlings[J]. Canadian Journal of Plant Science, 1990, 70(1): 307-310.
[62] Peltier G, Tysdal H. Hardiness studies with 2-year-old alfalfa plants[J]. Journal of Agriculture Research, 1931, 43(11): 931-955.
[63] Peltier G L, Tysdal H. A method for the determination of comparative hardiness in seedling alfalfas by controlled hardening and artificial freezing[J]. Journal of Agriculture Research, 1932, 44(5): 429-444.
[64] Patton A J, Reicher Z J. Zoysiagrass species and genotypes differ in their winter injury and freeze tolerance[J]. Crop Science, 2007, 47(4): 1619-1627.
[65] Cardona C, Duncan R, Lindstrom O. Low temperature tolerance assessment inpaspalum[J]. Crop Science, 1997, 37(4): 1283-1291.
[66] Fry J D, Lang N, Clifton R, et al. Freezing tolerance and carbohydrate content of low-temperature-acclimated and nonacclimated centipedegrass[J]. Crop Science, 1993, 33(5): 1051-1055.
[67] Maier F, Lang N, Fry J. Evaluation of an electrolyte leakage technique to predict st. Augustinegrass freezing tolerance[J]. HortScience, 1994, 29(4): 316-318.
[68] Sulc R, Albrecht K, Duke S. Leakage of intracellular substances as an indicator of freezing injury in alfalfa[J]. Crop Science, 1991, 31(2): 430-435.
[69] Stair D, Dahmer M, Bashaw E, et al. Freezing tolerance of selected pennisetum species[J]. International Journal of Plant Sciences, 1998, 159(4): 599-605.
[70] Mohapatra S S, Poole R J, Dhindsa R S. Changes in protein patterns and translatable messenger rna populations during cold acclimation of alfalfa[J]. Plant Physiology, 1987, 84(4): 1172.
[71] Levitt J. Responses of plants to environmental stresses. VolumeⅡ. Water, radiation, salt, and other stresses[M]. Academic Press, New York, 1980.
[72] Mohapatra S S, Poole R J, Dhindsa R S. Cold acclimation, freezing resistance and protein synthesis in alfalfa (Medicago sativa L. Cv. Saranac)[J]. Journal of Experimental Botany, 1987, 38(10): 1697.
[73] Arakeri H R, Schmid A. Cold resistance of various legumes and grasses in early stages of growth[D]. University of Minnesota, 1948.
[74] Pomeroy M, Fowler D. Use of lethal dose temperature estimates as indices of frost tolerance for wheat cold acclimated under natural and controlled environments[J]. Canadian Journal of Plant Science, 1973, 53(3): 489-494.
[75] Anderson J, Taliaferro C, Martin D. Evaluating freeze tolerance of bermudagrass in a controlled environment[J]. HortScience: a publication of the American Society for Horticultural Science (USA), 1993, 28(9): 955.
[76]赵宇光,吴渠来,许令妊,等.冷季紫花苜蓿和黄花苜蓿抗冻性的变化[J].中国草地学报, 1986(4): 15-18.
[77] Tisdal H, Pieters A. Cold hardiness of three species of lespedeza compared to that of alfalfa, red clover, and crownvetch[J]. Agronomy Journal, 1934, 26(11): 923-928.
[78] Hume D J, A.K.H. Jackson. Frost tolerance in soybean[J]. Crop Science, 1981, 21(5): 689-692.
[79] Hicks D R. Growth and development[M]. In AG Norman, ed, Soybean Physiology Agronomy and Utilization. Academic Press, New York, 1978.27-44.
[80] Arakeri H R, Schmid A. Cold resistance of various legumes and grasses in early stages ofgrowth[J]. Agronomy Journal, 1949, 41(5): 182-185.
[81] Coffman F. The minimum temperature of germination of seeds[J]. Agronomy Journal, 1923, 15(7): 257-270.
[82] Tysdal H, Pieters A. Cold resistance of three species of lespedeza compared to that of alfalfa, red clover, and crown vetch[J]. Journal of Agriculture Research, 1931, 43: 177-182.
[83] McDonald C. Germination response to temperature in tropical and subtropical pasture legumes. 1. Constant temperature[J]. Australian journal of experimental agriculture, 2002, 42(4): 407-420.
[84] Brar G, Gomez J, McMichael B, et al. Germination of twenty forage legumes as influenced by temperature[J]. Agronomy Journal, 1991, 83(1): 173-175.
[85] Klos K L E. Variation in alfalfa (Medicago sativa L.) for germination and seedling vigor at suboptimal temperatures: And laboratory and field response to selection within six alfalfa populations[D]. Iowa State University, 1999.
[86] Heinrichs D. Rate of germination of alfalfa varieties at four temperatures and relationship to winterhardiness[J]. Canadian Journal of Plant Science, 1967, 47(3): 301-304.
[87] Rodger J, Davis G. A rapid method for determining winterhardiness in alfalfa[J]. Agronomy Journal, 1957, 49(2): 88-92.
[88] Garcia-Huidobro J, Monteith J, Squire G R. Time, temperature and germination of pearl millet (Pennisetum typhoides S.&H.)ⅠConstant temperature. [J]. Journal of Experimental Botany, 1982, 33(2): 288-296.
[89]张红香.种子发芽生态研究[D].长春:东北师范大学生命科学院, 2008.
[90] Steinmaus S J, Prather T S, Holt J S. Estimation of base temperatures for nine weed species[J]. Journal of Experimental Botany, 2000, 51(343): 275-286.
[91] Trudgill D, Squire G, Thompson K. A thermal time basis for comparing the germination requirements of some british herbaceous plants[J]. New Phytologist, 2000, 145(1): 107-114.
[92] Larsen S U B, Martin B. Differences in thermal time requirement for germination of three turfgrass species[J]. Crop Science, 2005, 45(5): 2030-2037.
[93] Blinn P K, Station C A E. Alfalfa: The relation of type to hardiness[M]: Agricultural Experiment Station of the Agricultural College of Colorado, 1911.
[94] Oakley R A. Effect of the length of day on seedlings of alfalfa varieties and the possibility of utilizing this as a practical means of identification[M]. Government Printing Office, 1921.
[95] Schonhorst M, Carter R. Response of alfalfa varieties to temperatures and daylengths[J].Agronomy Journal, 1957, 49(3): 142-143.
[96] Castonguay Y, Nadeau P, Lechasseur P, et al. Differential accumulation of carbohydrates in alfalfa cultivars on contrasting winterhardiness[J]. Crop Science, 1995, 35(2): 509-516.
[97] Nittler L W, McKee G W, Newcomer J L. Principles and methods of testing alfalfa seed for varietal purity[J]. New York State Agricultural Experiment Station, 1964.
[98]卢欣石.中国苜蓿审定品种秋眠性研究[J].中国草地, 1998, (3): 1-5.
[99]于林清,王照兰,萨仁,等.中国新疆苜蓿野生种群秋眠性的研究[J].中国草地, 2001, 23(3): 13-16.
[100]毕玉芬,车伟光.新疆北部地区(北疆)苜蓿属植物秋眠性的研究[J].安徽农业大学学报, 2002, 29(4): 383-386.
[101]于林清,云锦凤,萨仁,等.紫花苜蓿国家审定品种的产量,再生性,秋眠性及持久性测定分析[J].草原与草坪, 2006(5): 12-17.
[102]毕玉芬,王晓云,区力松.云南苜蓿秋眠性评定技术标准的研究[J].云南农业大学学报, 2004, 19(2): 144-147.
[103]徐大伟,卢欣石.北京地区光温因子对不同秋眠等级苜蓿秋后再生的影响[J].草业科学, 2010, 27(4): 112-116.
[104]李崇巍.不同苜蓿品种抗逆性研究及评价[D].西北农林科技大学, 2002.
[105]于林清,云锦凤,郭九峰,等.苜蓿秋眠标准对照品种的幼苗形态与秋眠性,越冬率的关系[J].华北农学报, 2010, 25(2): 182-187.
[106]刘香萍.苜蓿品种间抗寒性能评价及其相关形态学与生理学研究[D].东北农业大学, 2004.
[107]王绛辉,卢欣石,严秀将,等.澳大利亚苜蓿抗寒性研究进展[J].中国农学通报, 2007, 23(8): 44-47.
[108] Smith D S, Struckmeyer E B. Gross morphology and starch accumulation in leaves of alfalfa plants grown at high and low temperatures1[J]. Crop Science, 1974, 14(3): 433.
[109]敖学成,傅平,柳茜.苜蓿子叶大小与秋眠生长特性相关的初步研究[J].草业与畜牧, 2010(3): 10-12.
[110]邓蓉,向清华,陈武,等.紫花苜蓿秋眠性的研究[J].草业科学, 2005, 22(2): 41-44.
[111]董静华.不同秋眠类型紫花苜蓿在华北地区农艺特性评价[D].北京林业大学, 2008.
[112] Garver S. Alfalfa root studies[M]. USDA Bulletin, 1087,1922.
[113] Barnes D K, Degenhart N R, Smith D M, et al. Root morphology of alfalfa plant introductions and north american cultivar[C]. In: 31st North American Alfalfa Improvement Conference, Beltsville, MD, 1988. 19-23.
[114] Johnson L, Marquez-Ortiz J, Barnes D, et al. Inheritance of root traits in alfalfa[J]. Crop Science, 1996, 36(6): 1482-1487.
[115] Hakl J, Fuksa P, antr ek J, et al. The development of lucerne root morphology traits under high initial stand density within a seven year period[J]. Plant, Soil and Environment, 2011, 57(2): 81-87.
[116] Carlson F. The effect of soil structure on the character of alfalfa root systems[J]. Agronomy Journal, 1925, 17(6): 336-345.
[117] McIntosh M. Genetic and soil moisture effects on the branching-root trait in alfalfa1[J]. Crop Science, 1981, 21(1): 15-18.
[118] Weaver J E. Root development of field crops[M].New York: McGraw Hill book company, 1926.
[119] Lamb J, Johnson L, Barnes D, et al. A method to characterize root morphology traits in alfalfa[J]. Canadian Journal of Plant Science, 2000, 80(1): 97-104.
[120] McIntosh M S, Miller D A. Development of root-branching in three alfalfa cultivars[J]. Crop Science, 1980, 20(6): 807-809.
[121] Smith D. The survival of winter-hardened legumes encased in ice[J]. Agronomy Journal, 1952, 44(9): 469-473.
[122] Foord K E, Teuber L R. Alfalfa seedling development[C]. In: Forage and Grassland Conference, Rochester, MN, 1982: 21-24.
[123]韩路.不同苜蓿品种的生产性能分析及评价[D].西北农林科技大学, 2002.
[124] Marquez-Ortiz J, Johnson L, Barnes D, et al. Crown morphology relationships among alfalfa plant introductions and cultivars[J]. Crop Science, 1996, 36(3): 766-770.
[125] Juan N A, Sheaffer C, Barnes D. Root and crown characteristics of alfalfas varying in fall dormancy[J]. Canadian Journal of Plant Science, 1994, 74(1): 125-127.
[126] Singh Y, Winch J. Morphological development of two alfalfa cultivars under various harvesting schedules[J]. Canadian Journal of Plant Science, 1974, 54(1): 79-87.
[127] Volenec J. Leaf area expansion and shoot elongation of diverse alfalfa germplasms1[J]. Crop Science, 1985, 25(5): 822-827.
[128]韩清芳.不同苜蓿(Medicago sativa)品种抗逆性,生产性能及品质特性研究[D].西北农林科技大学, 2003.
[129]吴新卫,韩清芳,贾志宽.不同苜蓿品种根颈和根系形态学特性比较及根系发育能力[J].西北农业学报, 2007, 16(2): 80-86.
[130]王月胜.不同苜蓿品种根系特性及其抗寒性关系的研究[D].中国农业科学院草原研究所, 2008.
[131]陈敏.直立型黄花苜蓿的研究[J].中国草地学报, 1980: 38-42.
[132]卢欣石,申玉龙.苜蓿秋眠性研究与利用[J].国外畜牧学:草原与牧草, 1991, (4): 1-4.
[133]刘玉华,贾志宽.苜蓿秋眠性的研究进展[J].陕西农业科学, 2002(7): 20-22.
[134] Riday H, Brummer E C. Heterosis of agronomic traits in alfalfa[J]. Crop Science, 2002, 42(4): 1081-1087.
[135] Baskin C C, Baskin J M. Germination ecophysiology of herbaceous plant species in a temperate region[J]. American Journal of Botany, 1988, 75(2): 286-305.
[136] Jami A A. Cardinal temperatures for germination of Kochia scoparia (L.)[J]. Journal of Arid Environments, 2007, 68(2): 308-314.
[137] Madakadze I, Madakadze K, Smith R. Base temperatures for seedling growth and their correlation with chilling sensitivity for warm-season grasses[J]. Crop Science, 2003, 43(3): 874-878.
[138] Alvarado V, Bradford K. A hydrothermal time model explains the cardinal temperatures for seed germination[J]. Plant, Cell & Environment, 2002, 25(8): 1061-1069.
[139] Probert R J. The role of temperature in germination ecophysiology[M]. In: Fenner, M. (ed.) Seeds: The Ecology of Regeneration in Plant Communities. CAB International, Wallingford, UK, 1992. 235-285.
[140] Bierhuizen J, Wagenvoort W. Some aspects of seed germination in vegetables. I. The determination and application of heat sums and minimum temperature for germination[J]. Scientia Horticulturae, 1974, 2(3): 213-219.
[141] Yeh D M, Atherton J. Cardinal temperatures and thermal requirements for germination of cineraria seed[J]. Journal of Horticultural Science and Biotechnology, 2000, 75(4): 476-480.
[142] Covell S, Ellis R, Roberts E, et al. The influence of temperature on seed germination rate in grain legumes[J]. Journal of Experimental Botany, 1986, 37(5): 705-715.
[143] Washitani I, Takenaka A. Germination responses of a non-dormant seed population of Amaranthus patulus Bertol. to constant temperatures in the sub-optimal range[J]. Plant, Cell and& Environment, 1984, 7(5): 353-358.
[144] Angus J, Cunningham R, Moncur M, et al. Phasic development in field crops. I. Thermal response in the seedling phase[J]. Field Crops Research, 1980, 3(4): 365-378.
[145] Ellis R, Covell S, Roberts E, et al. The influence of temperature on seed germination rate in grain legumes.Ⅱ. Intraspecific variation in chickpea at constant temperatures[J]. Journal of Experimental Botany, 1986, 37(10): 1503-1515.
[146] Mwale S, Azam-Ali S, Clark J, et al. Effect of temperature on the germination of sunflower (Helianthus annuus L.)[J]. Seed Science and Technology, 1994, 22(3): 565-571.
[147] Crauford P Q, Ellis R H, Summerfield R J. Development in cowpea (Vigna unguiculata).I. The influence of temperature on seed germination and seedling emergence[J]. Experimental Agriculture, 1996, 32(1): 1-12.
[148] Arnold C Y. The determination and significance of the base temperature in a linear heat unit system[J]. Journal of the American Society for Horticultural Science, 1959, 74(4): 430-445.
[149] Hardegree S, Van Vactor S. Predicting germination response of four cool-season range grasses to field-variable temperature regimes[J]. Environmental and Experimental Botany, 1999, 41(3): 209-217.
[150] Esechie H. Interaction of salinity and temperature on the germination of alfalfa cv cuf 101[J]. Agronomie, 1993, 13(4): 301-306.
[151] AOSA. Rules for testing seeds, in Proceedings of the association of official seed analysts[M]. Association of Official Seed Analysts. 1970. 1-116.
[152] Taggard K, Teuber L, Gibbs L. Notice of release of alfalfa germplasm selected under field conditions for fall growth[J]. Agronomy Progress Report, University of California, Davis, 2000, 268: 1-3.
[153] Flores J, Briones O. Plant life-form and germination in a mexican inter-tropical desert: Effects of soil water potential and temperature[J]. Journal of Arid Environments, 2001, 47(4): 485-497.
[154] Roundy B A, Biedenbender S H. Germination of warm-season grasses under constant and dynamic temperatures[J]. Journal of Range Management, 1996, 49(5): 425-431.
[155] Olivier F, Annandale J. Thermal time requirements for the development of green pea (Pisum sativum L.)[J]. Field Crops Research, 1998, 56(3): 301-307.
[156] Seefeldt S S, Kidwell K K, Waller J E. Base growth temperatures, germination rates and growth response of contemporary spring wheat (Triticum aestivum L.) cultivars from the us pacific northwest[J]. Field Crops Research, 2002, 75(1): 47-52.
[157] Tobe K, Li X, Omasa K. Seed germination and radicle growth of a halophyte, Kalidium caspicum (Chenopodiaceae)[J]. Annals of Botany, 2000, 85(3): 391-396.
[158] Gorai M, Neffati M. Germination responses of reaumuria vermiculata to salinity and temperature[J]. Annals of Applied Biology, 2007, 151(1): 53-59.
[159] Elci S, Kolsaricl O, Gecit H H. Field crops[M].Turkish Ankara: University Ziraat Fak Yayin, 1987.
[160] Balkaya A. Modelling the effect of temperature on the germination speed in some legume crops[J]. Journal of Agronomy, 2004, 3(3): 179-183.
[161] Hochman Z, Helyar K. Climatic and edaphic constraints to the persistence of legumes in pastures. In Persistence of forage legumes(Eds G C Marten et al). American Society ofAgronomy. Madison, Wis. 1989. 177-204.
[162] Brar G, Gomez J, McMichael B, et al. Root development of 12 forage legumes as affected by temperature[J]. Agronomy Journal, 1990, 82(5): 1024-1026.
[163] Klos K L E, Brummer E C. Field response to selection in alfalfa for germination rate and seedling vigor at low temperatures[J]. Crop Science, 2000, 40(5): 1227-1232.
[164] Ye C, Fukai S, Godwin I, et al. Cold tolerance in rice varieties at different growth stages[J]. Crop and Pasture Science, 2009, 60(4): 328-338.
[165] Ellis R, Simon G, Covell S. The influence of temperature on seed germination rate in grain legumes. Iii. A comparison of five faba bean genotypes at constant temperatures using a new screening method[J]. Journal of Experimental Botany, 1987, 38(6): 1033.
[166] Fidanza M, Dernoeden P, Zhang M. Degree-days for predicting smooth crabgrass emergence in cool-season turfgrasses[J]. Crop Science, 1996, 36(4): 990-996.
[167] Holshouser D L, Chandler J M, Wu H I. Temperature-dependent model for non-dormant seed germination and rhizome bud break of johnsongrass (Sorghum halepense)[J]. Weed Science, 1996, 44(2): 257-265.
[168] Jordan G L, Haferkamp M R. Temperature responses and calculated heat units for germination of several range grasses and shrubs[J]. Journal of Range Management, 1989, 42(1): 41-45.
[169] Ellis R, Butcher P. The effects of priming and 'natural' differences in quality amongst onion seed lots on the response of the rate of germination to temperature and the identification of the characteristics under genotypic control[J]. Journal of Experimental Botany, 1988, 39(7): 935-950.
[170] Bois J F, Winkel T, Lhomme J P, et al. Response of some andean cultivars of quinoa (Chenopodium quinoa Willd.) to temperature: Effects on germination, phenology, growth and freezing[J]. European Journal of Agronomy, 2006, 25(4): 299-308.
[171] Wang R, Bai Y, Tanino K. Effect of seed size and sub-zero imbibition-temperature on the thermal time model of winterfat (Eurotia lanata (Pursh) Moq.)[J]. Environmental and Experimental Botany, 2004, 51(3): 183-197.
[172] Trudgill D. Why do tropical poikilothermic organisms tend to have higher threshold temperatures for development than temperate ones?[J]. Functional Ecology, 1995, 9(1): 136-137.
[173] Trudgill D, Perry J. Thermal time and ecological strategies: a unifying hypothesis[J]. Annals of Applied Biology, 1994, 125(3): 521-532.
[174] Schwab P, Barnes D, Sheaffer C, et al. Factors affecting a laboratory evaluation of alfalfa cold tolerance[J]. Crop Science, 1996, 36(2): 318-324.
[175] Calder F, MacLeod L, Jackson L. Effect of soil moisture content and stage of development on cold-hardiness of the alfalfa plant[J]. Canadian Journal of Plant Science, 1965, 45(3): 211-218.
[176] Smith, R.R., and A.E. Kretschmer, Jr. Breeding and genetics of legume persistence[M]. In G.C. Marten et al. (ed.) Persistence of forage legumes. Am. Soc. Agron., Madison, WI 1989. 541-552..
[177] Limin A, Fowler D. Breeding for cold hardiness in winter wheat: Problems, progress and alien gene expression[J]. Field Crops Research, 1991, 27(3): 201-218.
[178] B¨|langer G, Castonguay Y, Bertrand A, et al. Winter damage to perennial forage crops in eastern canada: Causes, mitigation, and prediction[J]. Canadian Journal of Plant Science, 2006, 86(1): 33-47.
[179] Volenec J, Cunningham S, Haagenson D, et al. Physiological genetics of alfalfa improvement: Past failures, future prospects[J]. Field Crops Research, 2002, 75(2-3): 97-110.
[180] Dhont C C, Nadeau Y, Bélanger P, et al. Untimely fall harvest affects dry matter yield and root organic reserves in field-grown alfalfa[J]. Crop Science, 2004, 44(1): 144.
[181] Welbaum G, Bian D, Hill D, et al. Freezing tolerance, protein composition, and abscisic acid localization and content of pea epicotyl, shoot, and root tissue [J]. Journal of Experimental Botany, 1997, 48(3): 643.
[182] Paulsen G M. Effect of photoperiod and temperature on cold hardening in winter wheat [J]. Crop Science, 1968, 8(1): 29.
[183] Dexter S, Tottingham W, Graber L. Investigations of the hardiness of plants by measurement of electrical conductivity[J]. Plant Physiology, 1932, 7(1): 63.
[184] Heinrichs D, Troelsen J, Clark K. Winter hardiness evaluation in alfalfa[J]. Canadian Journal of Plant Science, 1960, 40(4): 638-644.
[185] Suzuki M. Evaluation of regrowth potential of perennial forage crops using triphenyltetrazolium chloride[J]. Canadian Journal of Plant Science, 1968, 48(1): 113.
[186] Malinowski D, Kramp W, Zuo B, et al. Supplemental irrigation and fall dormancy effects on alfalfa productivity in a semiarid, subtropical climate with a bimodal precipitation pattern[J]. Agronomy Journal, 2007, 99(3): 621.
[187] Fairey D, Fairey N, Lefkovitch L. The relationship between fall dormancy and germplasm source in north american alfalfa cultivars[J]. Canadian journal of plant science, 1996, 76(3): 429-433.
[188] Nittler L. The response of alfalfa varieties to photoperiod, color of light and temperature[J]. Agronomy Journal, 1959, 51(12): 727.
[189] Ueno M, Smith D. In?uence of temperature on seedling growth and carbohydrate composition of three alfalfa cultivars[J]. Agronomy Journal, 1970, 62: 764-767.
[190] Cunningham S, Volenec J. Seasonal carbohydrate and nitrogen metabolism in roots of contrasting alfalfa (Medicago sativa L.) cultivars[J]. Journal of Plant Physiology, 1998, 153(1-2): 220-225.
[191]扎西. 4种豆科牧草根系的观测研究[J].中国草业科学, 1987, 4(4): 56-57.
[192]赵明轩,谭成虎,何得元,等.驴驴蒿根系的研究[J].草业科学, 1990, 7(3): 55-57.
[193] Russell R S. Plant root systems: Their function and interaction with the soil[M]: McGraw-Hill Book Company (UK) Limited, 1977.
[194]孙启忠,韩建国.科尔沁沙地苜蓿根系和根颈特性[J].草地学报, 2001, 9(4): 269-276.
[195]姚爱兴,梁祖铎,王槐三.淮阴苜蓿主要种质特性研究[J].草业科学, 1990, 7(6): 25-29.
[196]吴新卫.不同秋眠级数苜蓿品种根系形态及吸水规律研究[D].西北农林科技大学, 2007.
[197]郭正刚,王锁民,张自和.紫花苜蓿品种间根系发育过程分析[J].应用与环境生物学报, 2003, 9(4): 367-371.
[198]万素梅,胡守林,黄勤慧,等.不同紫花苜蓿品种根系发育能力的研究[J].西北植物学报, 2004, 24(11): 2048-2052.
[199]鲍士旦.土壤农化分析[M].北京:中国农业出版社, 2000.
[200]熊顺贵.基础土壤学[M].北京:中国农业大学出版社, 2001.
[201]王富贵,于林清,田自华,等. 18个苜蓿品种根系特征及与地上生物量关系的研究[J].中国草地学报, 2011, 33(4): 51-57.
[202]史纪安,刘玉华,韩清芳,等.不同秋眠级数的紫花苜蓿品种根系发育能力研究[J].西北农业学报, 2009(4): 149-154.
[203] Hakl J. The root morphology of new czech lucerne candivars[J]. Scientia Agriculturae Bohemica, 2007, 38(1): 1-5.
[204]郭正刚,张自和.黄土高原丘陵沟壑区紫花苜蓿品种间根系发育能力的初步研究[J].应用生态学报, 2002, 13(8): 1007-1012.
[205]白文明,左强,黄元仿. Effect of water supply on root growth and water uptake alfalfa in wulanbuhe sandy region[J].植物生态学报, 2001, 25(1): 35-41.
[206] Smith D. Root branching of alfalfa varieties and strains[J]. Agronomy Journal, 1951, 43(11): 573-575.
[207]马其东,高振声,洪绂曾.不同苜蓿地方品种根系发育能力的评价和筛选[J].草业学报, 1999,8 (1): 42-49.
[208] Perfect E, Miller R, Burton B. Root morphology and vigor effects on winter heaving of established alfalfa[J]. Agronomy journal (USA), 1987, 79(6): 1061-1067.
[209] Frame J. Advances in forage legume technology[J]. Acta Pratacultural Science, 2001.10 (4): 1-17.
[210] Miller R M, Jastrow J D. Contributions of legumes to the formation and maintenance of soil structure[C]. In: D. Younie (ed.) Legumes in Sustainable Farming Systems. Occasional Symposium No. 30, British Grassland Society, Reading, UK..1996. 105-112.
[211] Sleugh B, Moore K J, George J R, et al. Binary legume-grass mixtures improve forage yield, quality, and seasonal distribution[J]. Agronomy Journal, 2000, 92(1): 24-29.
[212] Bazzaz F, Miao S. Successional status, seed size, and responses of tree seedlings to CO2, light, and nutrients[J]. Ecology, 1993, 74(1): 104-112.
[213] Walters M B, Reich P B. Growth of acer saccharum seedlings in deeply shaded understories of northern wisconsin: Effects of nitrogen and water availability[J]. Canadian Journal of Forest Research, 1997, 27(2): 237-247.
[214] Zheng Y, Xie Z, Yu Y, et al. Effects of burial in sand and water supply regime on seedling emergence of six species[J]. Annals of Botany, 2005, 95(7): 1237.
[215] Sanderson M A, Elwinger G F. Emergence and seedling structure of temperate grasses at different planting depths[J]. Agronomy Journal, 2004,96(3): 685-691.
[216] Ries R, Hofmann L. Grass seedling morphology when planted at different depths[J]. Journal of Range Management, 1995,48(3) : 218-223.
[217] Seiwa K, Watanabe A, Saitoh T, et al. Effects of burying depth and seed size on seedling establishment of Japanese chestnuts[J]. Castanea Crenata, 2002, 164(1): 149-156.
[218] Benvenuti S, Macchia M, Miele S. Light, temperature and burial depth effects on rumex obtusifolius seed germination and emergence[J]. Weed Research, 2001, 41(2): 177-186.
[219] Forcella F, Benech Arnold R L, Sanchez R, et al. Modeling seedling emergence[J]. Field Crops Research, 2000, 67(2): 123-139.
[220] Maun M. Adaptations of plants to burial in coastal sand dunes[J]. Canadian Journal of Botany, 1998, 76(5): 713-738.
[221] Arnott R. The effect of seed weight and depth of sowing on the emergence and early seedling growth of perennial ryegrass (Lolium perenne L.)[J]. Grass and Forage Science, 1969, 24(2): 104-110.
[222] Beveridge J L, Wilsie C P. Influence of depth of planting, seed size, and variety on emergence and seeding vigor in alfalfa[J]. Agronomy Journal, 1959, 51(12): 731-734.
[223] Fulbright T E, Wilson A, Redente E F. Green needlegrass seedling morphology in relation to planting depth[J]. Journal of Range Management, 1984, 38(3): 266-270.
[224] Maun M, Lapierre J. Effects of burial by sand on seed germination and seedling emergence of four dune species[J]. American Journal of Botany, 1986, 73(3): 450-455.
[225] Maun M, Riach S. Morphology of caryopses, seedlings and seedling emergence of the grass calamovilfa longifolia from various depths in sand[J]. Oecologia, 1981, 49(1): 137-142.
[226] Redmann R, Qi M. Impacts of seeding depth on emergence and seedling structure in eight perennial grasses[J]. Canadian Journal of Botany, 1992, 70(1): 133-139.
[227] Ren J, Tao L, Liu X M. Effect of sand burial depth on seed germination and seedling emergence of Calligonum L. Species[J]. Journal of Arid Environments, 2002, 51(4): 603-611.
[228] Lanini W, Orloff S, Vargas R, et al. Oat companion crop seeding rate effect of alfalfa establishment, yield, and weed control[J]. Agronomy Journal, 1991, 83(2): 330-333.
[229] Simmons S, Sheaffer C, Rasmusson D, et al. Alfafa establishment with barley and oat companion crops differing in stature[J]. Agronomy Journal, 1995, 87(2): 268-272.
[230] Cuomo G J, Johnson D G, Head W A. Interseeding kura clover and birdsfoot trefoil into existing cool-season grass pastures[J]. Agronomy Journal, 2001, 93(2): 458-462.
[231] Groya F, Sheaffer C. Establishment of sod-seeded alfalfa at various levels of soil moisture and grass competition[J]. Agronomy Journal, 1981, 73(3): 560.
[232] Taylor R W, Allinson D W. Legume establishment in grass sods using minimum-tillage seeding techniques without herbicide application: Forage yield and quality[J]. Agronomy Journal, 1983, 75(2): 167.
[233] Michaud R, Lehman W, Rumbaugh M. World distribution and historical development[J]. Alfalfa and alfalfa improvement, 1988, 29: 25-56.
[234] Lesins K A, Lesins I. Genus Medicago (Leguminosae): A taxogenetic study[M]. Kluwer Dordrecht Netherlands. 1979.
[235] Chen H, Maun M. Effects of sand burial depth on seed germination and seedling emergence of cirsium pitcheri[J]. Plant Ecology, 1999, 140(1): 53-60.
[236] Tobe K, Zhang L, Omasa K. Seed germination and seedling emergence of three annuals growing on desert sand dunes in China[J]. Annals of Botany, 2005, 95(4): 649.
[237] Gardener C J, Whiteman L V, Jones R M. Patterns of seedling emergence over 5 years from seed of 38 species placed on the soil surface under shade and full sunlight in the seasonally dry tropics[J]. Tropical Grasslands, 2001, 35(4): 218-225.
[238] Becker P, Rabenold P E, Idol J R, et al. Water potential gradients for gaps and slopes in a panamanian tropical moist forest's dry season[J]. Journal of Tropical Ecology, 1988, 4(2): 173-184.
[239] Newman P, Moser L E. Grass seedling emergence, morphology, and establishment as affected by planting depth[J]. Agronomy Journal, 1988,80(3): 383-387.
[240] Poorter L, Rose S A. Light-dependent changes in the relationship between seed mass and seedling traits: A meta-analysis for rain forest tree species[J]. Oecologia, 2005, 142(3): 378-387.
[241] Kitajima K. Relative importance of photosynthetic traits and allocation patterns as correlates of seedling shade tolerance of 13 tropical trees[J]. Oecologia, 1994, 98(3): 419-428.
[242] Beon M S, Bartsch N. Early seedling growth of pine (Pinus densiflora) and oaks (Quercus serrata, Q. mongolica, Q. variabilis) in response to light intensity and soil moisture[J]. Plant Ecology, 2003, 167(1): 97-105.
[243] Vandenbussche F, Verbelen J P, Van Der Straeten D. Of light and length: Regulation of hypocotyl growth in arabidopsis[J]. Bioessays, 2005, 27(3): 275-284.
[244] McWilliam J, Clements R, Dowling P. Some factors influencing the germination and early seedling development of pasture plants[J]. Australian Journal of Agricultural Research, 1970, 21(1): 19-32.
[245] Walters M, Kruger E, Reich P. Relative growth rate in relation to physiological and morphological traits for northern hardwood tree seedlings: Species, light environment and ontogenetic considerations[J]. Oecologia, 1993, 96(2): 219-231.
[246] Walters M B, Reich P B. Seed size, nitrogen supply, and growth rate affect tree seedling survival in deep shade[J]. Ecology, 2000, 81(7): 1887-1901.
[247] Leishman M R. Does the seed size/number trade-off model determine plant community structure? An assessment of the model mechanisms and their generality[J]. Oikos, 2001, 93(2): 294-302.
[248] Leishman M R, Westoby M. Hypotheses on seed size: Tests using the semiarid flora of western new south wales, australia[J]. American Naturalist, 1994, 143(5): 890-906.
[249] Westoby M, Leishman M, Lord J, et al. Comparative ecology of seed size and dispersal[J]. Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, 1996, 351(1345): 1309.
[250] Salisbury E J. The reproductive capacity of plants[M]. London: George Bell & Sons. 1942.
[251] Heckman N L, Horst G L, Gaussoin R E. Planting depth effect on emergence and morphology of buffalograss seedlings[J]. Hortscience, 2002, 37(3): 506-507.
[2] Russelle M P. Alfalfa[J]. American Scientist, 2001, 89: 252-261.
[3]耿华珠.中国苜蓿[M].中国农业出版社, 1995.
[4]全国畜牧总站.中国草业统计(2010年)[G]. 2011.
[5] Castonguay Y, Laberge S, Brummer E C, et al. Alfalfa winter hardiness: A research retrospective and integrated perspective[J]. Advances in Agronomy, 2006, 90: 203-265.
[6]洪绂曾.苜蓿科学[M].中国农业出版社, 2009.
[7]朱飞雪.黄花苜蓿不同品系的遗传多样性及其快速繁殖研究[D].甘肃农业大学, 2008.
[8] Riday H, Brummer E C. Forage yield heterosis in alfalfa[J]. Crop Science, 2002, 42(3): 716-723.
[9] Berdahl J, Wilton A, Frank A. Survival and agronomic performance of 25 alfalfa cultivars and strains interseeded into rangeland[J]. Journal of Range Management, 1989, 42(4): 312-316.
[10] Mortenson M C, Schuman G E, Ingram L J. Carbon sequestration in rangelands interseeded with yellow-flowering alfalfa (Medicago sativa ssp. falcata)[J]. Environmental Management, 2004, 33 (suppl.1): 475-481.
[11] Mortenson M C, Schuman G E, Ingram L J, et al. Forage production and quality of a mixed-grass rangeland interseeded with Medicago sativa ssp. falcata[J]. Rangeland Ecology and Management, 2005, 58(5): 505-513.
[12] Riday H B, Moore E C, Kenneth J. Heterosis of forage quality in alfalfa[J]. Crop Science, 2002, 42(4): 1088-1093.
[13] Waldron L. First generation crosses between two alfalfa species[J]. Journal of American Socity Agronomy, 1920, 12: 133-143.
[14] Riday H, Brummer E C. Heterosis in a broad range of alfalfa germplasm[J]. Crop Science, 2005, 45(1): 8-17.
[15] Brummer E C. Capturing heterosis in forage crop cultivar development[J]. Crop Science, 1999, 39(4): 943-954.
[16] Sriwatanapongse S, Wilsie C. Intra- and inter-variety crosses of Medicago sativa L. and Medicago falcata[J]. Crop Science, 1968, 8(4): 465-466.
[17]王俊杰.中国黄花苜蓿野生种质资源研究[D].内蒙古农业大学, 2008.
[18] Haagenson D, Cunningham S, Volenec J. Root physiology of less fall dormant, winter hardy alfalfa selections[J]. Crop Science, 2003, 43(4): 1441-1447.
[19] Wang C, Ma B, Yan X, et al. Yields of alfalfa varieties with different fall-dormancy levels in a temperate environment[J]. Agronomy Journal, 2009, 101(5): 1147-1152.
[20] Castonguay Y, Michaud R, Nadeau P, et al. An indoor screening method for improvement of freezing tolerance in alfalfa[J]. Crop Science, 2009, 49(3): 809-818.
[21] McKenzie J, Paquin R, Duke S. Cold and heat tolerance, In“Alfalfa and alfalfa improvement”(A. A. Hanson, D. K. Barnes, and R. R. Hill, Jr., Eds.).[M]. Madison Wisconsin, USA.1988. 259-302.
[22] Belanger G R, Castonguay P, Bootsma Y, et al. Climate change and winter survival of perennial forage crops in eastern canada[J]. Agronomy Journal, 2002, 94(5): 1120.
[23] Brouwer D J, Duke S H, Osborn T C. Mapping genetic factors associated with winter hardiness, fall growth, and freezing injury in autotetraploid alfalfa[J]. Crop Science, 2000, 40(5): 1387-1396.
[24] Sheaffer C, Barnes D, Warnes D, et al. Seeding-year cutting affects winter survival and its association with fall growth score in alfalfa[J]. Crop Science, 1992, 32(1): 225-231.
[25] Barnes D. Minnesota fall dormancy and its relationship to winter injury[C]. 1991: 14-16.
[26] Nittler L W, Gibbs G H. The response of alfalfa varieties to photoperiod, color of light and temperature[J]. Agronomy Journal, 1959, 51(12): 727-730.
[27] Sprague M, Fuelleman R. Measurements of recovery after cutting and fall dormancy of varieties and strains of alfalfa, Medicago sativa[J]. Agronomy Journal, 1941, 33(5): 437.
[28] Brummer E C, Shah M M, Luth D. Reexamining the relationship between fall dormancy and winter hardiness in alfalfa[J]. Crop Science, 2000, 40(4): 971-977.
[29] Cunningham S, Volenec J, Teuber J. Winter hardiness, root physiology, and gene expression in successive fall dormancy selections from 'Mesilla' and 'CUF 101' alfalfa[J]. Crop Science, 2001, 41(4): 1091.
[30] Teuber L, Taggard K, Gibbs L, et al. Check cultivars, locations, and management of fall dormancy evaluation[C]. In: North American Alfalfa Improvement Conference Committee, Beltsville. MD, 1998.25.
[31] Larson K L, Smith D. Association of various morphological characters and seed germination with the winter hardiness of alfalfa[J]. Crop Science, 1963, 3(3): 234-237.
[32] Larson K L, Smith D. Reliability of various plant constituents and artificial freezing methods in determining winterhardiness of alfalfa1[J]. Crop Science, 1964, 4(4): 413-417.
[33] Schwab P, Barnes D, Sheaffer C. The relationship between field winter injury and fall growth score for 251 alfalfa cultivars[J]. Crop Science, 1996, 36(2): 418-426.
[34] Smith D. Winter injury and the survival of forage plants[J]. Herbage Abstracts, 1964, 34: 203-209.
[35] Brouwer D, Duke S, Osborn T. Comparison of seedlings and cuttings for evaluating winter hardiness in alfalfa[J]. Crop Science, 1998, 38(6): 1704-1707.
[36] Kohel R J, Davis R L. The inheritance of cold resistance and its relation to fall growth in F2 and BC1 generation of alfalfa[J]. Agronomy Journal, 1960, 52(4): 234-237.
[37] Smith D. Association of fall growth habit and winter survival in alfalfa[J]. Canadian Journal of Plant Science, 1961, 41(2): 244-251.
[38] Busbice T, Wilsie C. Fall growth, winter hardiness, recovery after cutting and wilt resistance in F2 progenies of vernal dupuits alfalfa crosses[J]. Crop Science, 1965, 5(5): 429-432.
[39] Daday H. Genetic relationship between cold hardiness and growth at low temperature in medicago sativa[J]. Heredity, 1964, 19(2): 173-179.
[40] Weishaar M A B, Volenec E C, Moore J J, et al. Improving winter hardiness in nondormant alfalfa germplasm[J]. Crop Science, 2005, 45(1): 60.
[41] Haagenson D, Joern S, Volenec B. Autumn defoliation effects on alfalfa winter survival, root physiology, and gene expression[J]. Crop Science, 2003, 43(4): 1340.
[42] Knipe B, Reisen P, McCaslin M. The relationship between fall dormancy and stand persistence in alfalfa varieties[C]. In: 1998 California Alfalfa Symposium, 1998. 203-208.
[43] Teuber L R, taggard K L, Gibbs G H, et al. Fall dormancy, The United States Department of Agriculture, Editor. 1998.
[44] Barnes D, Bingham E, Murphy R, et al. Alfalfa germplasm in the United States: Genetic vulnerability, use, and maintenance[J]. USDA Technology Bulletin,1977, 1571:21.
[45] Lehman W F, Marble V L, Erwin D C, et al. Nondormant alfalfa, past, present, and future[C]. In: California Alfalfa Symp. Process, Minneapolis, MN, 1987: Coop Ext University of California, Davis: 29-38.
[46] Barnes D, Smith D, Stucker R, et al. Fall dormancy in alfalfa: A valuable predictive tool[C]. In: 26th Alfalfa Improvement Conference, Brookings, SD, 1978: 1-34.
[47] Johnson L, Marquez-Ortiz J, Lamb J, et al. Root morphology of alfalfa plant introductions and cultivars[J]. Crop Science, 1998, 38(2): 497-502.
[48] Perry M C, Mcintosh M, Wiebold W, et al. Genetic analysis of cold hardiness and dormancy in alfalfa[J]. Genome, 1987, 29(1): 144-149.
[49]何云,刘圈炜,王成章,等.苜蓿秋眠性研究进展[J].草业科学, 2005, 22(11): 25-30.
[50] Barnes D K, Smith D M, Teuber L R, et al. Fall dormancy[C]. In: 3rd ed. North American Alfalfa Improvement Conference, 1991: A1-A2.
[51] Reisen P M, Gurrier C G, Melton B A. Measurement of fall dormancy in solid-and space planted plots[Z]. 1990.
[52] Schnieder M. Relationship between unifoliate internode length and fall dormancy in alfalfa[D]. Davis,CA: University of California, 1984.
[53] Kallenbach R, Roberts C, Teuber L, et al. Estimation of fall dormancy in alfalfa by near infrared reflectance spectroscopy[J]. Crop Science, 2001, 41(3): 774-777.
[54]王红柳,岳征文,卢欣石.基于近红外光谱技术与支持向量机的苜蓿秋眠类型测定研究[J].光谱学与光谱分析, 2011, 31(6): 1510-1513.
[55] Ariss J J, Vandemark G J. Assessment of genetic diversity among nondormant and semidormant alfalfa populations using sequence-related amplified polymorphisms[J]. Crop Science, 2007, 47(6): 2274-2284.
[56] Yu K, Pauls K. Rapid estimation of genetic relatedness among heterogeneous populations of alfalfa by random amplification of bulked genomic DNA samples[J]. TAG Theoretical and Applied Genetics, 1993, 86(6): 788-794.
[57] Welsh J, McClelland M. Fingerprinting genomes using pcr with arbitrary primers[J]. Nucleic Acids Research, 1990, 18(24): 7213-7218.
[58] Badaruddin M, Meyer D. Factors modifying frost tolerance of legume species[J]. Crop Science, 2001, 41(1): 1911-1916.
[59] Meyer D W, and M. Badaruddin. Frost tolerance fo ten seedling legume species at four growth stages[J]. Crop Science, 2001, 41(6): 1838-1842.
[60] Heichel G, Henjum K. Fall dormancy response of alfalfa investigated with reciprocal cleft grafts[J]. Crop Science, 1990, 30(5): 1123-1127.
[61] Cloutier Y, Pelletier L, Michaud R. Development of a test for freezing tolerance in young alfalfa seedlings[J]. Canadian Journal of Plant Science, 1990, 70(1): 307-310.
[62] Peltier G, Tysdal H. Hardiness studies with 2-year-old alfalfa plants[J]. Journal of Agriculture Research, 1931, 43(11): 931-955.
[63] Peltier G L, Tysdal H. A method for the determination of comparative hardiness in seedling alfalfas by controlled hardening and artificial freezing[J]. Journal of Agriculture Research, 1932, 44(5): 429-444.
[64] Patton A J, Reicher Z J. Zoysiagrass species and genotypes differ in their winter injury and freeze tolerance[J]. Crop Science, 2007, 47(4): 1619-1627.
[65] Cardona C, Duncan R, Lindstrom O. Low temperature tolerance assessment inpaspalum[J]. Crop Science, 1997, 37(4): 1283-1291.
[66] Fry J D, Lang N, Clifton R, et al. Freezing tolerance and carbohydrate content of low-temperature-acclimated and nonacclimated centipedegrass[J]. Crop Science, 1993, 33(5): 1051-1055.
[67] Maier F, Lang N, Fry J. Evaluation of an electrolyte leakage technique to predict st. Augustinegrass freezing tolerance[J]. HortScience, 1994, 29(4): 316-318.
[68] Sulc R, Albrecht K, Duke S. Leakage of intracellular substances as an indicator of freezing injury in alfalfa[J]. Crop Science, 1991, 31(2): 430-435.
[69] Stair D, Dahmer M, Bashaw E, et al. Freezing tolerance of selected pennisetum species[J]. International Journal of Plant Sciences, 1998, 159(4): 599-605.
[70] Mohapatra S S, Poole R J, Dhindsa R S. Changes in protein patterns and translatable messenger rna populations during cold acclimation of alfalfa[J]. Plant Physiology, 1987, 84(4): 1172.
[71] Levitt J. Responses of plants to environmental stresses. VolumeⅡ. Water, radiation, salt, and other stresses[M]. Academic Press, New York, 1980.
[72] Mohapatra S S, Poole R J, Dhindsa R S. Cold acclimation, freezing resistance and protein synthesis in alfalfa (Medicago sativa L. Cv. Saranac)[J]. Journal of Experimental Botany, 1987, 38(10): 1697.
[73] Arakeri H R, Schmid A. Cold resistance of various legumes and grasses in early stages of growth[D]. University of Minnesota, 1948.
[74] Pomeroy M, Fowler D. Use of lethal dose temperature estimates as indices of frost tolerance for wheat cold acclimated under natural and controlled environments[J]. Canadian Journal of Plant Science, 1973, 53(3): 489-494.
[75] Anderson J, Taliaferro C, Martin D. Evaluating freeze tolerance of bermudagrass in a controlled environment[J]. HortScience: a publication of the American Society for Horticultural Science (USA), 1993, 28(9): 955.
[76]赵宇光,吴渠来,许令妊,等.冷季紫花苜蓿和黄花苜蓿抗冻性的变化[J].中国草地学报, 1986(4): 15-18.
[77] Tisdal H, Pieters A. Cold hardiness of three species of lespedeza compared to that of alfalfa, red clover, and crownvetch[J]. Agronomy Journal, 1934, 26(11): 923-928.
[78] Hume D J, A.K.H. Jackson. Frost tolerance in soybean[J]. Crop Science, 1981, 21(5): 689-692.
[79] Hicks D R. Growth and development[M]. In AG Norman, ed, Soybean Physiology Agronomy and Utilization. Academic Press, New York, 1978.27-44.
[80] Arakeri H R, Schmid A. Cold resistance of various legumes and grasses in early stages ofgrowth[J]. Agronomy Journal, 1949, 41(5): 182-185.
[81] Coffman F. The minimum temperature of germination of seeds[J]. Agronomy Journal, 1923, 15(7): 257-270.
[82] Tysdal H, Pieters A. Cold resistance of three species of lespedeza compared to that of alfalfa, red clover, and crown vetch[J]. Journal of Agriculture Research, 1931, 43: 177-182.
[83] McDonald C. Germination response to temperature in tropical and subtropical pasture legumes. 1. Constant temperature[J]. Australian journal of experimental agriculture, 2002, 42(4): 407-420.
[84] Brar G, Gomez J, McMichael B, et al. Germination of twenty forage legumes as influenced by temperature[J]. Agronomy Journal, 1991, 83(1): 173-175.
[85] Klos K L E. Variation in alfalfa (Medicago sativa L.) for germination and seedling vigor at suboptimal temperatures: And laboratory and field response to selection within six alfalfa populations[D]. Iowa State University, 1999.
[86] Heinrichs D. Rate of germination of alfalfa varieties at four temperatures and relationship to winterhardiness[J]. Canadian Journal of Plant Science, 1967, 47(3): 301-304.
[87] Rodger J, Davis G. A rapid method for determining winterhardiness in alfalfa[J]. Agronomy Journal, 1957, 49(2): 88-92.
[88] Garcia-Huidobro J, Monteith J, Squire G R. Time, temperature and germination of pearl millet (Pennisetum typhoides S.&H.)ⅠConstant temperature. [J]. Journal of Experimental Botany, 1982, 33(2): 288-296.
[89]张红香.种子发芽生态研究[D].长春:东北师范大学生命科学院, 2008.
[90] Steinmaus S J, Prather T S, Holt J S. Estimation of base temperatures for nine weed species[J]. Journal of Experimental Botany, 2000, 51(343): 275-286.
[91] Trudgill D, Squire G, Thompson K. A thermal time basis for comparing the germination requirements of some british herbaceous plants[J]. New Phytologist, 2000, 145(1): 107-114.
[92] Larsen S U B, Martin B. Differences in thermal time requirement for germination of three turfgrass species[J]. Crop Science, 2005, 45(5): 2030-2037.
[93] Blinn P K, Station C A E. Alfalfa: The relation of type to hardiness[M]: Agricultural Experiment Station of the Agricultural College of Colorado, 1911.
[94] Oakley R A. Effect of the length of day on seedlings of alfalfa varieties and the possibility of utilizing this as a practical means of identification[M]. Government Printing Office, 1921.
[95] Schonhorst M, Carter R. Response of alfalfa varieties to temperatures and daylengths[J].Agronomy Journal, 1957, 49(3): 142-143.
[96] Castonguay Y, Nadeau P, Lechasseur P, et al. Differential accumulation of carbohydrates in alfalfa cultivars on contrasting winterhardiness[J]. Crop Science, 1995, 35(2): 509-516.
[97] Nittler L W, McKee G W, Newcomer J L. Principles and methods of testing alfalfa seed for varietal purity[J]. New York State Agricultural Experiment Station, 1964.
[98]卢欣石.中国苜蓿审定品种秋眠性研究[J].中国草地, 1998, (3): 1-5.
[99]于林清,王照兰,萨仁,等.中国新疆苜蓿野生种群秋眠性的研究[J].中国草地, 2001, 23(3): 13-16.
[100]毕玉芬,车伟光.新疆北部地区(北疆)苜蓿属植物秋眠性的研究[J].安徽农业大学学报, 2002, 29(4): 383-386.
[101]于林清,云锦凤,萨仁,等.紫花苜蓿国家审定品种的产量,再生性,秋眠性及持久性测定分析[J].草原与草坪, 2006(5): 12-17.
[102]毕玉芬,王晓云,区力松.云南苜蓿秋眠性评定技术标准的研究[J].云南农业大学学报, 2004, 19(2): 144-147.
[103]徐大伟,卢欣石.北京地区光温因子对不同秋眠等级苜蓿秋后再生的影响[J].草业科学, 2010, 27(4): 112-116.
[104]李崇巍.不同苜蓿品种抗逆性研究及评价[D].西北农林科技大学, 2002.
[105]于林清,云锦凤,郭九峰,等.苜蓿秋眠标准对照品种的幼苗形态与秋眠性,越冬率的关系[J].华北农学报, 2010, 25(2): 182-187.
[106]刘香萍.苜蓿品种间抗寒性能评价及其相关形态学与生理学研究[D].东北农业大学, 2004.
[107]王绛辉,卢欣石,严秀将,等.澳大利亚苜蓿抗寒性研究进展[J].中国农学通报, 2007, 23(8): 44-47.
[108] Smith D S, Struckmeyer E B. Gross morphology and starch accumulation in leaves of alfalfa plants grown at high and low temperatures1[J]. Crop Science, 1974, 14(3): 433.
[109]敖学成,傅平,柳茜.苜蓿子叶大小与秋眠生长特性相关的初步研究[J].草业与畜牧, 2010(3): 10-12.
[110]邓蓉,向清华,陈武,等.紫花苜蓿秋眠性的研究[J].草业科学, 2005, 22(2): 41-44.
[111]董静华.不同秋眠类型紫花苜蓿在华北地区农艺特性评价[D].北京林业大学, 2008.
[112] Garver S. Alfalfa root studies[M]. USDA Bulletin, 1087,1922.
[113] Barnes D K, Degenhart N R, Smith D M, et al. Root morphology of alfalfa plant introductions and north american cultivar[C]. In: 31st North American Alfalfa Improvement Conference, Beltsville, MD, 1988. 19-23.
[114] Johnson L, Marquez-Ortiz J, Barnes D, et al. Inheritance of root traits in alfalfa[J]. Crop Science, 1996, 36(6): 1482-1487.
[115] Hakl J, Fuksa P, antr ek J, et al. The development of lucerne root morphology traits under high initial stand density within a seven year period[J]. Plant, Soil and Environment, 2011, 57(2): 81-87.
[116] Carlson F. The effect of soil structure on the character of alfalfa root systems[J]. Agronomy Journal, 1925, 17(6): 336-345.
[117] McIntosh M. Genetic and soil moisture effects on the branching-root trait in alfalfa1[J]. Crop Science, 1981, 21(1): 15-18.
[118] Weaver J E. Root development of field crops[M].New York: McGraw Hill book company, 1926.
[119] Lamb J, Johnson L, Barnes D, et al. A method to characterize root morphology traits in alfalfa[J]. Canadian Journal of Plant Science, 2000, 80(1): 97-104.
[120] McIntosh M S, Miller D A. Development of root-branching in three alfalfa cultivars[J]. Crop Science, 1980, 20(6): 807-809.
[121] Smith D. The survival of winter-hardened legumes encased in ice[J]. Agronomy Journal, 1952, 44(9): 469-473.
[122] Foord K E, Teuber L R. Alfalfa seedling development[C]. In: Forage and Grassland Conference, Rochester, MN, 1982: 21-24.
[123]韩路.不同苜蓿品种的生产性能分析及评价[D].西北农林科技大学, 2002.
[124] Marquez-Ortiz J, Johnson L, Barnes D, et al. Crown morphology relationships among alfalfa plant introductions and cultivars[J]. Crop Science, 1996, 36(3): 766-770.
[125] Juan N A, Sheaffer C, Barnes D. Root and crown characteristics of alfalfas varying in fall dormancy[J]. Canadian Journal of Plant Science, 1994, 74(1): 125-127.
[126] Singh Y, Winch J. Morphological development of two alfalfa cultivars under various harvesting schedules[J]. Canadian Journal of Plant Science, 1974, 54(1): 79-87.
[127] Volenec J. Leaf area expansion and shoot elongation of diverse alfalfa germplasms1[J]. Crop Science, 1985, 25(5): 822-827.
[128]韩清芳.不同苜蓿(Medicago sativa)品种抗逆性,生产性能及品质特性研究[D].西北农林科技大学, 2003.
[129]吴新卫,韩清芳,贾志宽.不同苜蓿品种根颈和根系形态学特性比较及根系发育能力[J].西北农业学报, 2007, 16(2): 80-86.
[130]王月胜.不同苜蓿品种根系特性及其抗寒性关系的研究[D].中国农业科学院草原研究所, 2008.
[131]陈敏.直立型黄花苜蓿的研究[J].中国草地学报, 1980: 38-42.
[132]卢欣石,申玉龙.苜蓿秋眠性研究与利用[J].国外畜牧学:草原与牧草, 1991, (4): 1-4.
[133]刘玉华,贾志宽.苜蓿秋眠性的研究进展[J].陕西农业科学, 2002(7): 20-22.
[134] Riday H, Brummer E C. Heterosis of agronomic traits in alfalfa[J]. Crop Science, 2002, 42(4): 1081-1087.
[135] Baskin C C, Baskin J M. Germination ecophysiology of herbaceous plant species in a temperate region[J]. American Journal of Botany, 1988, 75(2): 286-305.
[136] Jami A A. Cardinal temperatures for germination of Kochia scoparia (L.)[J]. Journal of Arid Environments, 2007, 68(2): 308-314.
[137] Madakadze I, Madakadze K, Smith R. Base temperatures for seedling growth and their correlation with chilling sensitivity for warm-season grasses[J]. Crop Science, 2003, 43(3): 874-878.
[138] Alvarado V, Bradford K. A hydrothermal time model explains the cardinal temperatures for seed germination[J]. Plant, Cell & Environment, 2002, 25(8): 1061-1069.
[139] Probert R J. The role of temperature in germination ecophysiology[M]. In: Fenner, M. (ed.) Seeds: The Ecology of Regeneration in Plant Communities. CAB International, Wallingford, UK, 1992. 235-285.
[140] Bierhuizen J, Wagenvoort W. Some aspects of seed germination in vegetables. I. The determination and application of heat sums and minimum temperature for germination[J]. Scientia Horticulturae, 1974, 2(3): 213-219.
[141] Yeh D M, Atherton J. Cardinal temperatures and thermal requirements for germination of cineraria seed[J]. Journal of Horticultural Science and Biotechnology, 2000, 75(4): 476-480.
[142] Covell S, Ellis R, Roberts E, et al. The influence of temperature on seed germination rate in grain legumes[J]. Journal of Experimental Botany, 1986, 37(5): 705-715.
[143] Washitani I, Takenaka A. Germination responses of a non-dormant seed population of Amaranthus patulus Bertol. to constant temperatures in the sub-optimal range[J]. Plant, Cell and& Environment, 1984, 7(5): 353-358.
[144] Angus J, Cunningham R, Moncur M, et al. Phasic development in field crops. I. Thermal response in the seedling phase[J]. Field Crops Research, 1980, 3(4): 365-378.
[145] Ellis R, Covell S, Roberts E, et al. The influence of temperature on seed germination rate in grain legumes.Ⅱ. Intraspecific variation in chickpea at constant temperatures[J]. Journal of Experimental Botany, 1986, 37(10): 1503-1515.
[146] Mwale S, Azam-Ali S, Clark J, et al. Effect of temperature on the germination of sunflower (Helianthus annuus L.)[J]. Seed Science and Technology, 1994, 22(3): 565-571.
[147] Crauford P Q, Ellis R H, Summerfield R J. Development in cowpea (Vigna unguiculata).I. The influence of temperature on seed germination and seedling emergence[J]. Experimental Agriculture, 1996, 32(1): 1-12.
[148] Arnold C Y. The determination and significance of the base temperature in a linear heat unit system[J]. Journal of the American Society for Horticultural Science, 1959, 74(4): 430-445.
[149] Hardegree S, Van Vactor S. Predicting germination response of four cool-season range grasses to field-variable temperature regimes[J]. Environmental and Experimental Botany, 1999, 41(3): 209-217.
[150] Esechie H. Interaction of salinity and temperature on the germination of alfalfa cv cuf 101[J]. Agronomie, 1993, 13(4): 301-306.
[151] AOSA. Rules for testing seeds, in Proceedings of the association of official seed analysts[M]. Association of Official Seed Analysts. 1970. 1-116.
[152] Taggard K, Teuber L, Gibbs L. Notice of release of alfalfa germplasm selected under field conditions for fall growth[J]. Agronomy Progress Report, University of California, Davis, 2000, 268: 1-3.
[153] Flores J, Briones O. Plant life-form and germination in a mexican inter-tropical desert: Effects of soil water potential and temperature[J]. Journal of Arid Environments, 2001, 47(4): 485-497.
[154] Roundy B A, Biedenbender S H. Germination of warm-season grasses under constant and dynamic temperatures[J]. Journal of Range Management, 1996, 49(5): 425-431.
[155] Olivier F, Annandale J. Thermal time requirements for the development of green pea (Pisum sativum L.)[J]. Field Crops Research, 1998, 56(3): 301-307.
[156] Seefeldt S S, Kidwell K K, Waller J E. Base growth temperatures, germination rates and growth response of contemporary spring wheat (Triticum aestivum L.) cultivars from the us pacific northwest[J]. Field Crops Research, 2002, 75(1): 47-52.
[157] Tobe K, Li X, Omasa K. Seed germination and radicle growth of a halophyte, Kalidium caspicum (Chenopodiaceae)[J]. Annals of Botany, 2000, 85(3): 391-396.
[158] Gorai M, Neffati M. Germination responses of reaumuria vermiculata to salinity and temperature[J]. Annals of Applied Biology, 2007, 151(1): 53-59.
[159] Elci S, Kolsaricl O, Gecit H H. Field crops[M].Turkish Ankara: University Ziraat Fak Yayin, 1987.
[160] Balkaya A. Modelling the effect of temperature on the germination speed in some legume crops[J]. Journal of Agronomy, 2004, 3(3): 179-183.
[161] Hochman Z, Helyar K. Climatic and edaphic constraints to the persistence of legumes in pastures. In Persistence of forage legumes(Eds G C Marten et al). American Society ofAgronomy. Madison, Wis. 1989. 177-204.
[162] Brar G, Gomez J, McMichael B, et al. Root development of 12 forage legumes as affected by temperature[J]. Agronomy Journal, 1990, 82(5): 1024-1026.
[163] Klos K L E, Brummer E C. Field response to selection in alfalfa for germination rate and seedling vigor at low temperatures[J]. Crop Science, 2000, 40(5): 1227-1232.
[164] Ye C, Fukai S, Godwin I, et al. Cold tolerance in rice varieties at different growth stages[J]. Crop and Pasture Science, 2009, 60(4): 328-338.
[165] Ellis R, Simon G, Covell S. The influence of temperature on seed germination rate in grain legumes. Iii. A comparison of five faba bean genotypes at constant temperatures using a new screening method[J]. Journal of Experimental Botany, 1987, 38(6): 1033.
[166] Fidanza M, Dernoeden P, Zhang M. Degree-days for predicting smooth crabgrass emergence in cool-season turfgrasses[J]. Crop Science, 1996, 36(4): 990-996.
[167] Holshouser D L, Chandler J M, Wu H I. Temperature-dependent model for non-dormant seed germination and rhizome bud break of johnsongrass (Sorghum halepense)[J]. Weed Science, 1996, 44(2): 257-265.
[168] Jordan G L, Haferkamp M R. Temperature responses and calculated heat units for germination of several range grasses and shrubs[J]. Journal of Range Management, 1989, 42(1): 41-45.
[169] Ellis R, Butcher P. The effects of priming and 'natural' differences in quality amongst onion seed lots on the response of the rate of germination to temperature and the identification of the characteristics under genotypic control[J]. Journal of Experimental Botany, 1988, 39(7): 935-950.
[170] Bois J F, Winkel T, Lhomme J P, et al. Response of some andean cultivars of quinoa (Chenopodium quinoa Willd.) to temperature: Effects on germination, phenology, growth and freezing[J]. European Journal of Agronomy, 2006, 25(4): 299-308.
[171] Wang R, Bai Y, Tanino K. Effect of seed size and sub-zero imbibition-temperature on the thermal time model of winterfat (Eurotia lanata (Pursh) Moq.)[J]. Environmental and Experimental Botany, 2004, 51(3): 183-197.
[172] Trudgill D. Why do tropical poikilothermic organisms tend to have higher threshold temperatures for development than temperate ones?[J]. Functional Ecology, 1995, 9(1): 136-137.
[173] Trudgill D, Perry J. Thermal time and ecological strategies: a unifying hypothesis[J]. Annals of Applied Biology, 1994, 125(3): 521-532.
[174] Schwab P, Barnes D, Sheaffer C, et al. Factors affecting a laboratory evaluation of alfalfa cold tolerance[J]. Crop Science, 1996, 36(2): 318-324.
[175] Calder F, MacLeod L, Jackson L. Effect of soil moisture content and stage of development on cold-hardiness of the alfalfa plant[J]. Canadian Journal of Plant Science, 1965, 45(3): 211-218.
[176] Smith, R.R., and A.E. Kretschmer, Jr. Breeding and genetics of legume persistence[M]. In G.C. Marten et al. (ed.) Persistence of forage legumes. Am. Soc. Agron., Madison, WI 1989. 541-552..
[177] Limin A, Fowler D. Breeding for cold hardiness in winter wheat: Problems, progress and alien gene expression[J]. Field Crops Research, 1991, 27(3): 201-218.
[178] B¨|langer G, Castonguay Y, Bertrand A, et al. Winter damage to perennial forage crops in eastern canada: Causes, mitigation, and prediction[J]. Canadian Journal of Plant Science, 2006, 86(1): 33-47.
[179] Volenec J, Cunningham S, Haagenson D, et al. Physiological genetics of alfalfa improvement: Past failures, future prospects[J]. Field Crops Research, 2002, 75(2-3): 97-110.
[180] Dhont C C, Nadeau Y, Bélanger P, et al. Untimely fall harvest affects dry matter yield and root organic reserves in field-grown alfalfa[J]. Crop Science, 2004, 44(1): 144.
[181] Welbaum G, Bian D, Hill D, et al. Freezing tolerance, protein composition, and abscisic acid localization and content of pea epicotyl, shoot, and root tissue [J]. Journal of Experimental Botany, 1997, 48(3): 643.
[182] Paulsen G M. Effect of photoperiod and temperature on cold hardening in winter wheat [J]. Crop Science, 1968, 8(1): 29.
[183] Dexter S, Tottingham W, Graber L. Investigations of the hardiness of plants by measurement of electrical conductivity[J]. Plant Physiology, 1932, 7(1): 63.
[184] Heinrichs D, Troelsen J, Clark K. Winter hardiness evaluation in alfalfa[J]. Canadian Journal of Plant Science, 1960, 40(4): 638-644.
[185] Suzuki M. Evaluation of regrowth potential of perennial forage crops using triphenyltetrazolium chloride[J]. Canadian Journal of Plant Science, 1968, 48(1): 113.
[186] Malinowski D, Kramp W, Zuo B, et al. Supplemental irrigation and fall dormancy effects on alfalfa productivity in a semiarid, subtropical climate with a bimodal precipitation pattern[J]. Agronomy Journal, 2007, 99(3): 621.
[187] Fairey D, Fairey N, Lefkovitch L. The relationship between fall dormancy and germplasm source in north american alfalfa cultivars[J]. Canadian journal of plant science, 1996, 76(3): 429-433.
[188] Nittler L. The response of alfalfa varieties to photoperiod, color of light and temperature[J]. Agronomy Journal, 1959, 51(12): 727.
[189] Ueno M, Smith D. In?uence of temperature on seedling growth and carbohydrate composition of three alfalfa cultivars[J]. Agronomy Journal, 1970, 62: 764-767.
[190] Cunningham S, Volenec J. Seasonal carbohydrate and nitrogen metabolism in roots of contrasting alfalfa (Medicago sativa L.) cultivars[J]. Journal of Plant Physiology, 1998, 153(1-2): 220-225.
[191]扎西. 4种豆科牧草根系的观测研究[J].中国草业科学, 1987, 4(4): 56-57.
[192]赵明轩,谭成虎,何得元,等.驴驴蒿根系的研究[J].草业科学, 1990, 7(3): 55-57.
[193] Russell R S. Plant root systems: Their function and interaction with the soil[M]: McGraw-Hill Book Company (UK) Limited, 1977.
[194]孙启忠,韩建国.科尔沁沙地苜蓿根系和根颈特性[J].草地学报, 2001, 9(4): 269-276.
[195]姚爱兴,梁祖铎,王槐三.淮阴苜蓿主要种质特性研究[J].草业科学, 1990, 7(6): 25-29.
[196]吴新卫.不同秋眠级数苜蓿品种根系形态及吸水规律研究[D].西北农林科技大学, 2007.
[197]郭正刚,王锁民,张自和.紫花苜蓿品种间根系发育过程分析[J].应用与环境生物学报, 2003, 9(4): 367-371.
[198]万素梅,胡守林,黄勤慧,等.不同紫花苜蓿品种根系发育能力的研究[J].西北植物学报, 2004, 24(11): 2048-2052.
[199]鲍士旦.土壤农化分析[M].北京:中国农业出版社, 2000.
[200]熊顺贵.基础土壤学[M].北京:中国农业大学出版社, 2001.
[201]王富贵,于林清,田自华,等. 18个苜蓿品种根系特征及与地上生物量关系的研究[J].中国草地学报, 2011, 33(4): 51-57.
[202]史纪安,刘玉华,韩清芳,等.不同秋眠级数的紫花苜蓿品种根系发育能力研究[J].西北农业学报, 2009(4): 149-154.
[203] Hakl J. The root morphology of new czech lucerne candivars[J]. Scientia Agriculturae Bohemica, 2007, 38(1): 1-5.
[204]郭正刚,张自和.黄土高原丘陵沟壑区紫花苜蓿品种间根系发育能力的初步研究[J].应用生态学报, 2002, 13(8): 1007-1012.
[205]白文明,左强,黄元仿. Effect of water supply on root growth and water uptake alfalfa in wulanbuhe sandy region[J].植物生态学报, 2001, 25(1): 35-41.
[206] Smith D. Root branching of alfalfa varieties and strains[J]. Agronomy Journal, 1951, 43(11): 573-575.
[207]马其东,高振声,洪绂曾.不同苜蓿地方品种根系发育能力的评价和筛选[J].草业学报, 1999,8 (1): 42-49.
[208] Perfect E, Miller R, Burton B. Root morphology and vigor effects on winter heaving of established alfalfa[J]. Agronomy journal (USA), 1987, 79(6): 1061-1067.
[209] Frame J. Advances in forage legume technology[J]. Acta Pratacultural Science, 2001.10 (4): 1-17.
[210] Miller R M, Jastrow J D. Contributions of legumes to the formation and maintenance of soil structure[C]. In: D. Younie (ed.) Legumes in Sustainable Farming Systems. Occasional Symposium No. 30, British Grassland Society, Reading, UK..1996. 105-112.
[211] Sleugh B, Moore K J, George J R, et al. Binary legume-grass mixtures improve forage yield, quality, and seasonal distribution[J]. Agronomy Journal, 2000, 92(1): 24-29.
[212] Bazzaz F, Miao S. Successional status, seed size, and responses of tree seedlings to CO2, light, and nutrients[J]. Ecology, 1993, 74(1): 104-112.
[213] Walters M B, Reich P B. Growth of acer saccharum seedlings in deeply shaded understories of northern wisconsin: Effects of nitrogen and water availability[J]. Canadian Journal of Forest Research, 1997, 27(2): 237-247.
[214] Zheng Y, Xie Z, Yu Y, et al. Effects of burial in sand and water supply regime on seedling emergence of six species[J]. Annals of Botany, 2005, 95(7): 1237.
[215] Sanderson M A, Elwinger G F. Emergence and seedling structure of temperate grasses at different planting depths[J]. Agronomy Journal, 2004,96(3): 685-691.
[216] Ries R, Hofmann L. Grass seedling morphology when planted at different depths[J]. Journal of Range Management, 1995,48(3) : 218-223.
[217] Seiwa K, Watanabe A, Saitoh T, et al. Effects of burying depth and seed size on seedling establishment of Japanese chestnuts[J]. Castanea Crenata, 2002, 164(1): 149-156.
[218] Benvenuti S, Macchia M, Miele S. Light, temperature and burial depth effects on rumex obtusifolius seed germination and emergence[J]. Weed Research, 2001, 41(2): 177-186.
[219] Forcella F, Benech Arnold R L, Sanchez R, et al. Modeling seedling emergence[J]. Field Crops Research, 2000, 67(2): 123-139.
[220] Maun M. Adaptations of plants to burial in coastal sand dunes[J]. Canadian Journal of Botany, 1998, 76(5): 713-738.
[221] Arnott R. The effect of seed weight and depth of sowing on the emergence and early seedling growth of perennial ryegrass (Lolium perenne L.)[J]. Grass and Forage Science, 1969, 24(2): 104-110.
[222] Beveridge J L, Wilsie C P. Influence of depth of planting, seed size, and variety on emergence and seeding vigor in alfalfa[J]. Agronomy Journal, 1959, 51(12): 731-734.
[223] Fulbright T E, Wilson A, Redente E F. Green needlegrass seedling morphology in relation to planting depth[J]. Journal of Range Management, 1984, 38(3): 266-270.
[224] Maun M, Lapierre J. Effects of burial by sand on seed germination and seedling emergence of four dune species[J]. American Journal of Botany, 1986, 73(3): 450-455.
[225] Maun M, Riach S. Morphology of caryopses, seedlings and seedling emergence of the grass calamovilfa longifolia from various depths in sand[J]. Oecologia, 1981, 49(1): 137-142.
[226] Redmann R, Qi M. Impacts of seeding depth on emergence and seedling structure in eight perennial grasses[J]. Canadian Journal of Botany, 1992, 70(1): 133-139.
[227] Ren J, Tao L, Liu X M. Effect of sand burial depth on seed germination and seedling emergence of Calligonum L. Species[J]. Journal of Arid Environments, 2002, 51(4): 603-611.
[228] Lanini W, Orloff S, Vargas R, et al. Oat companion crop seeding rate effect of alfalfa establishment, yield, and weed control[J]. Agronomy Journal, 1991, 83(2): 330-333.
[229] Simmons S, Sheaffer C, Rasmusson D, et al. Alfafa establishment with barley and oat companion crops differing in stature[J]. Agronomy Journal, 1995, 87(2): 268-272.
[230] Cuomo G J, Johnson D G, Head W A. Interseeding kura clover and birdsfoot trefoil into existing cool-season grass pastures[J]. Agronomy Journal, 2001, 93(2): 458-462.
[231] Groya F, Sheaffer C. Establishment of sod-seeded alfalfa at various levels of soil moisture and grass competition[J]. Agronomy Journal, 1981, 73(3): 560.
[232] Taylor R W, Allinson D W. Legume establishment in grass sods using minimum-tillage seeding techniques without herbicide application: Forage yield and quality[J]. Agronomy Journal, 1983, 75(2): 167.
[233] Michaud R, Lehman W, Rumbaugh M. World distribution and historical development[J]. Alfalfa and alfalfa improvement, 1988, 29: 25-56.
[234] Lesins K A, Lesins I. Genus Medicago (Leguminosae): A taxogenetic study[M]. Kluwer Dordrecht Netherlands. 1979.
[235] Chen H, Maun M. Effects of sand burial depth on seed germination and seedling emergence of cirsium pitcheri[J]. Plant Ecology, 1999, 140(1): 53-60.
[236] Tobe K, Zhang L, Omasa K. Seed germination and seedling emergence of three annuals growing on desert sand dunes in China[J]. Annals of Botany, 2005, 95(4): 649.
[237] Gardener C J, Whiteman L V, Jones R M. Patterns of seedling emergence over 5 years from seed of 38 species placed on the soil surface under shade and full sunlight in the seasonally dry tropics[J]. Tropical Grasslands, 2001, 35(4): 218-225.
[238] Becker P, Rabenold P E, Idol J R, et al. Water potential gradients for gaps and slopes in a panamanian tropical moist forest's dry season[J]. Journal of Tropical Ecology, 1988, 4(2): 173-184.
[239] Newman P, Moser L E. Grass seedling emergence, morphology, and establishment as affected by planting depth[J]. Agronomy Journal, 1988,80(3): 383-387.
[240] Poorter L, Rose S A. Light-dependent changes in the relationship between seed mass and seedling traits: A meta-analysis for rain forest tree species[J]. Oecologia, 2005, 142(3): 378-387.
[241] Kitajima K. Relative importance of photosynthetic traits and allocation patterns as correlates of seedling shade tolerance of 13 tropical trees[J]. Oecologia, 1994, 98(3): 419-428.
[242] Beon M S, Bartsch N. Early seedling growth of pine (Pinus densiflora) and oaks (Quercus serrata, Q. mongolica, Q. variabilis) in response to light intensity and soil moisture[J]. Plant Ecology, 2003, 167(1): 97-105.
[243] Vandenbussche F, Verbelen J P, Van Der Straeten D. Of light and length: Regulation of hypocotyl growth in arabidopsis[J]. Bioessays, 2005, 27(3): 275-284.
[244] McWilliam J, Clements R, Dowling P. Some factors influencing the germination and early seedling development of pasture plants[J]. Australian Journal of Agricultural Research, 1970, 21(1): 19-32.
[245] Walters M, Kruger E, Reich P. Relative growth rate in relation to physiological and morphological traits for northern hardwood tree seedlings: Species, light environment and ontogenetic considerations[J]. Oecologia, 1993, 96(2): 219-231.
[246] Walters M B, Reich P B. Seed size, nitrogen supply, and growth rate affect tree seedling survival in deep shade[J]. Ecology, 2000, 81(7): 1887-1901.
[247] Leishman M R. Does the seed size/number trade-off model determine plant community structure? An assessment of the model mechanisms and their generality[J]. Oikos, 2001, 93(2): 294-302.
[248] Leishman M R, Westoby M. Hypotheses on seed size: Tests using the semiarid flora of western new south wales, australia[J]. American Naturalist, 1994, 143(5): 890-906.
[249] Westoby M, Leishman M, Lord J, et al. Comparative ecology of seed size and dispersal[J]. Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, 1996, 351(1345): 1309.
[250] Salisbury E J. The reproductive capacity of plants[M]. London: George Bell & Sons. 1942.
[251] Heckman N L, Horst G L, Gaussoin R E. Planting depth effect on emergence and morphology of buffalograss seedlings[J]. Hortscience, 2002, 37(3): 506-507.