水杨酸对低温胁迫下藜豆种子萌发和幼苗生理特性的影响

【目的】研究外源水杨酸（SA）对低温胁迫条件下藜豆种子萌发和幼苗生理特性的影响。【方法】将用蒸馏水浸种的藜豆种子置于15，20，25，30，35，40 ℃可控温培养箱中培养，4 d时测定发芽势，7 d时测定发芽率、发芽指数及幼苗的芽长、主根长、侧根数,确定其适宜的萌发温度。分别用0，0.5，1.0，1.5，2.0，2.5 mmol/L的SA浸泡藜豆种子，然后进行培养，萌发时温度控制在15 ℃，幼苗生长温度控制在20 ℃，4 d时测发芽势，7 d时测定发芽率、发芽指数，2片真叶时测定幼苗叶绿素、丙二醛（MDA）含量及过氧化物酶（SOD）和超氧化物歧化酶（POD）活性。【结果】（1）藜豆种子萌发适宜的温度为25～35 ℃。（2）低温胁迫下，随外源SA浓度的增大，藜豆种子的发芽率、发芽势、发芽指数以及幼苗叶片的POD和SOD活性均呈先上升后下降的变化趋势，在SA浓度为1.5 mmol/L达最大值，而MDA含量呈现先下降后上升的变化趋势；藜豆幼苗叶片叶绿素含量在不同SA浓度之间差异不显著。【结论】实际生产中，应将藜豆种子萌发的温度尽可能控制在25～35 ℃。外源SA能提高藜豆的抗寒性，其浸种浓度以1.5 mmol/L为宜。

Effects of salicylic acid on the germination of velvetbean seeds and phyological characteristics of velvetbean seedlings under cold stress

【Objective】 The research was carried out to study the effects of salicylic acid(SA) on the germination of velvetbean seeds and physiological characteristics of the velvetbean seedling under cold stress.【Method】 The velvetbean seeds were soaked with distilled water and cultured in the temperature-controlled culture box at 15,20,25,30,35 and 40 ℃,respectively.The germination vigor was measured after 4 days.The germination rate,germination index,and stem length,root length and number of lateral roots of the seedlings were measured after 7 days to determine the optimum germination temperature.The seeds were soaked with different concentrations(0,0.5,1.0,1.5,2.0 and 2.5 mmol/L)of SA.The germination temperature was controlled at 15 ℃ and the growth temperature of the seedlings was controlled at 20 ℃.The germination vigor was measured after 4 days.The germination rate and germination index were determined after 7 days.Chlorophyll content,MDA content,SOD activity and POD activity of the seedlings were determined at two-leaf stage.【Result】(1) The suitable temperature for germination of the velvetbeen seeds was 25-35 ℃.(2) Under cold stress,with the increase of exogenous SA concentrations,the germination rate,germination vigor,germination index,and activities of POD and SOD in the seedling leaves showed the trend of increase first and then the trend of decrease,but MDA content decreased first and then increased.There were no significant differences in Chlorophyll contents among different SA concentrations.【Conclusion】 In practice,the germination temperature for the velvetbean seeds should be controlled between 25-35 ℃.SA can increase the chilling resistance of the velvetbean and the optimum treatment concentration of SA is 1.5 mmol/L.