30份苜蓿种质材料对低温胁迫的生理响应及其耐寒性评价

Physiological response and cold tolerance evaluation of 30 alfalfa germplasm to low temperature stress

摘要:

【目的】 筛选和评价耐低温苜蓿种质。【方法】 采用营养液沙培法，对生长30 d的30份国内外苜蓿种质进行低温胁迫处理。以室温生长幼苗为对照，在-7 ℃分别经过2、4、6、8 h处理后测定供试苜蓿的生理指标。【结果】 随低温胁迫时间延长，供试苜蓿叶绿素a、叶绿素b、总叶绿素含量递减，较对照分别降低6.1%~71.10%、6.61%~63.01%、6.18%~69.03%，电导率和丙二醛含量递增，较对照分别增加44.6%~55.54%、8.49%~47.7%，脯氨酸、可溶性糖和可溶性蛋白含量及过氧化物酶和过氧化氢酶活性先增后降且在低温胁迫6 h时增至最大，超氧化物歧化物活性呈先增后降再增趋势并在低温胁迫4 h时增幅最高、6 h时增幅最低。【结论】 经隶属函数综合评价，可将30份苜蓿分为4类，其中新品系P1、P2、P3、P4耐低温性好，可用于苜蓿耐低温新品种选育研究。

Abstract:

【Objective】 The aim of the study is to screen and evaluate low temperature tolerant alfalfa germplasm.【Method】 30 alfalfa germplasm growing for 30 days at home and abroad were treated with low temperature stress by nutrient solution sand culture method. The physiological indexes of alfalfa were measured at -7 ℃ after 2 h， 4 h，6 h and 8 h treatment.【Result】 With the extension of low temperature stress time，the contents of chlorophyll a， chlorophyll b and total chlorophyll decreased by 6. 1%~71. 10%，6. 61%~63. 01% and 6. 18%~69. 03% compared with the control，respectively. The electrical conductivity and malondialdehyde content increased. Compared with the control，the contents of proline，soluble sugar and soluble protein and the activities of peroxidase and catalase first increased and then decreased，and increased to the maximum under low temperature stress for 6 h. The activity of superoxide dismutants increased first，then decreased and then increased again，with the highest increase at 4 h and the lowest increase at 6 h.【Conclusion】 The 30 alfalfa can be divided into 4 categories by the comprehensive evaluation of membership function，among which the new strains P1，P2，P3 and P4 have good low temperature tolerance， and can be used for the breeding of new alfalfa varieties with low temperature tolerance.