玉米花期高温响应的基因型差异及其生理机制

摘要

以耐热基因型浚单20和热敏感基因型驻玉309为材料,分别于花前(吐丝前0～8 d)和花后(吐丝后0～8d)高温处理,研究了对产量的影响及其生理机制.结果表明,花后高温胁迫使2个基因型玉米花粉活力和籽粒ATP酶活性均下降,其中驻玉309下降达显著水平;高温胁迫导致2个基因型玉米产量显著下降,浚单20产量下降幅度小于驻玉309,且花后高温处理影响大于花前处理.花前和花后高温胁迫均使浚单20叶片的SOD、POD和CAT活性显著升高,而花前高温使驻玉309叶片SOD、POD活性升高,CAT活性下降,花后高温使驻玉309叶片SOD、POD和CAT的活性均下降.高温处理使2个基因型丙二醛(MDA)含量升高,浚单20升高的幅度显著小于驻玉309.高温胁迫降低了2个基因型的叶片光合速率,浚单20减小的幅度显著小于驻玉309.高温胁迫使浚单20的根系活力显著升高,驻玉309的根系活力显著降低.结果提示,在高温胁迫下保持较强的根系活力、叶片较高的光合速率和抗氧化能力及籽粒ATP酶活性是耐热玉米基因型具有较高产量的重要生理原因,也是耐高温胁迫的重要生理特征.%High temperature is one of the key limiting factors leading to serious yield reduction in maize production. The effect of high temperature treatments during flowering (0-8 d before silking and 0-8 d after silking) on yield and physiological response was investigated using heat-tolerant maize genotype Xundan 20 and heat-sensitive maize genotype Zhuyu 309. The results showed that high temperature treatment significantly reduced pollen fertility rate in heat-sensitive genotype, but the effect was similar to that of control in heat-tolerant genotype. The heat-sensitive genotype had a significant reduction in grain yield with a longer reduction rate under the treatment after flowering than before flowering, which was less affected for heat-tolerant genotype. The heat-stress treatment significantly increased the activities of enzymes for the leaves for the heat-tolerant genotype, while decreased the activities of enzymes involved in antioxidant system in heat-sensitive genotype. High temperature reduced photosyn-thetic rate in ear leaves and ATPase activity in kernels for both the heat-sensitive and heat-tolerant genotypes, but the decrease was not significant for the heat-tolerant genotype. High temperature increased malondialdehyde content in ear leaves and reduced root activity for heat-sensitive genotype. However, root activity of heat-tolerant genotypes increased significantly under high temperature. These results suggested that higher root activity, higher ATPase activity in kernels, and higher photosynthetic rate and activities of antioxidant enzymes in leaves would be important physiological Iraits leading to a higher grain yield for a heat-tolerant maize genotype.