灌浆期低温对玉米籽粒的伤害作用

Chilling Injury of Kernel of Maize Plant Stressed at Filling Stage

在灌浆期(抽雄后20天),玉米植株经10℃低温处理5天(120小时),籽粒超氧物歧化酶活性下降,膜脂过氧化作用增强,对生物膜系统产生直接伤害,电解质外渗率增大。电镜下可观察到细胞质膜,线粒体破坏;胞间连丝膨大变形,甚至于断裂;粗糙内质网损伤或卷曲;淀粉粒破裂、变形或相互融合。进而引起生理代谢紊乱,使可溶性糖和游离氨基酸含量增加,淀粉、蛋白质含量下降。阻碍籽粒灌浆,降低粒重,引起减产。

Maize plants were stressed for 5 days in plant growth chamber (E15) at filling stage (20th day after tasselling). Chilling stress decreased the activity of superoxide dismutase and increased membrane-lipid peroxidation in seeds, which directly damaged biological membrane system and led to a sharp increment in electrolyte leakage in tissues. Under microscope, significant ultrastructural changes were observed; mitochondria and protoplasmic membrane were damaged; plasmodesmata swelled, deformed or even ruptured; rough endoplasmic reticula were destroyed or warped; starch granules were damaged, deformed and merged each other. Ultrastructural changes disordered metabolism. The content of soluble sugar and free amino acids was raised, and that of starch, protein was decreased, which impeded seed filling process, and caused a noticeable reduction in the weight of grain, and in turn, the yield.