草地早熟禾苗期耐低温的生理特性研究

Physiological Characteristics of Low Temperature Tolerance in Poa pratensis Seedling Stage

为了探究不同抗性草地早熟禾苗期对低温胁迫的生理特性差异,以10个常用草地早熟禾品种为试验材料,将幼苗叶片进行不同程度的低温胁迫处理,利用细胞伤害率和对应的低温度梯度进行Logistic方程拟合,获得半致死温度(LT50)并筛选抗寒品种和低温敏感品种,并以二者为试验材料进行相关生理指标的测定和相关性分析。结果表明,草地早熟禾‘普瑞芬’的LT_(50)为-17.5℃,表现出较好的抗寒性,‘帝国’的LT_(50)为-3.2℃,表现出对低温的敏感性;经低温胁迫处理后抗寒品种‘普瑞芬’的相对电导率和丙二醛含量显著下降并低于低温敏感品种‘帝国’,而‘普瑞芬’幼苗中干物质含量、相对含水量和苗长等生长指标和叶绿素含量、渗透调节物质(游离脯氨酸、可溶性糖和可溶性蛋白)和抗氧化酶活性(SOD、POD和CAT)均高于‘帝国’;经相关性分析表明,低温对草地早熟禾幼苗的干物质,苗长和根长及渗透调节物质含量影响较大且各指标之间相互作用。

In order to explore the differences in physiological characteristics of Poa pratensis seedlings with different resistance to low-temperature stress,a total of ten widely utilized P.pratensis varieties were used as experimental materials,and the seedling leaves were subjected to different degrees of low-temperature stress,and the cell damage rate and corresponding low temperature gradient were used to fit the Logistic equations.The semi-lethal temperature(LT_(50))was obtained,and cold-resistant varieties and low-temperature sensitive varieties were screened,and the relevant physiological parameters were determined and the correlation analyses was carried out.The findings indicated that the LT_(50) of P.pratensis‘Prafin’was-17.5℃,showing good cold resistance,and the LT50 of‘Empire’was-3.2℃,showing low temperature sensitivity.After low-temperature stress treatment,the relative conductivity and malondialdehyde content of cold-resistant variety‘Prafin’decreased significantly and were lower than that of low temperature sensitive variety‘Empire’.The growth indexes such as dry matter content,relative water content and seedling length,chlorophyll content,osmoregulatory substances(free proline,soluble sugars and soluble proteins)and antioxidant enzyme activities(SOD,POD and CAT)of‘Prafin’seedlings were higher than those of‘Empire’seedlings.The correlation analysis indicated that low temperature had great effects on the dry matter,seedling length and root length,and the content of osmoregulatory substances in P.pratensis seedlings and there was interaction between indicators.