基于生理指标确定河套灌区玉米春霜冻的气象指标

Determining the meteorological indexes of spring frost in Hetao irrigation district based on physiological indexes of maize

霜冻是河套灌区发生频率较高的农业气象灾害之一。本文以河套灌区广泛种植的玉米中晚熟品种科河8号为试验材料,以常温(20℃左右)为对照,设置5℃^-5℃的低温环境,对玉米幼苗分别进行1 h、3 h、5 h处理,对比观测试验前后玉米各项生理指标的变化情况。逆境生理研究能更好地理解不同程度的低温胁迫下植物的生理生化变化,可基于此确定霜冻预报的气温指标。研究结果表明:随着处理温度的降低和低温胁迫时间的延长,玉米幼苗叶绿素含量呈稳定下降的趋势;可溶性糖含量、SOD活性、丙二醛含量先升高后下降,最高值出现在-2℃和-3℃。通过对以上3个指标变化特点的分析表明:4叶玉米幼苗比3叶的抗寒性更强;可溶性蛋白含量先下降后上升,最低值出现在-2℃;各低温处理均导致玉米幼苗的净光合作用速率、气孔导度、单叶水分利用率下降。参照本文及过冷却点的试验结果,制定河套地区玉米春霜冻的最低气温指标如下:轻霜冻,0℃~3.0℃;中霜冻,-2.5℃~0℃;重霜冻,<-2.5℃。

Frost is one of the agricultural meteorological disasters occurred frequently in Hetao irrigation district. We used Kehe No.8 maize,a mid-late maturing variety widely planted in Hetao irrigation area,as the test material. 5℃ to-5℃ low temperature environment was set up,allowing the treatments of maize seedlings for 1 h,3h,and 5 h. Comparisons between the physiological index changes before and after treatments were analyzed. Physiology research under stress could result in insightful understandings of the physiological and biochemical changes in plants under various low temperature treatments,which could be used to determine the meteorological indexes of spring frost. The results showed that with the decrease of temperature and increase of time under low temperature treatment,chlorophyll content of maize seedlings showed a steady downward trend. While,soluble sugar content,SOD activity and MDA content became increased first and then went decreased,and the highest value appeared at-2℃ and-3℃. The analyses of these three physiological indexes showed that the cold resistance capability of the4-leaf maize seedling was stronger than that of the 3-leaf one. Soluble protein content was decreased first and then became increased,and the lowest value appeared at- 2℃. All the low temperature treatments resulted in decreasing of net photosynthetic rate,stomatal conductance and leaf water use rate of maize seedling. According to the results and the supercooling points of maize,the minimum temperature indexes of spring frost in Hetao irrigation district were as follows： light frost,0℃ ∽ 3℃; moderate frost,-2.5℃ ∽ 0℃ and heavy frost,-2.5℃.