土壤水分胁迫对小麦根系与旗叶衰老的影响

EFFECTS OF SOIL WATER STRESS ON THE SENESCENCE OF ROOT SYSTEM AND FLAG LEAVES IN WHEAT

随土壤水分胁迫加剧，旗叶、根中的超氧化物歧化酶（ＳＯＤ）、过氧化氢酶（ＣＡＴ）活性降低，膜脂过氧化产物丙二醛（ＭＤＡ）含量增加，花后１４ｄ为膜脂过氧化作用加重的转折点，此时受水分胁迫愈重，旗叶与根中ＳＯＤ、ＣＡＴ活性降低愈迅速，ＭＤＡ含量迅速升高，根系活力、旗叶与根中可溶性蛋白质含量骤降，加重了膜脂过氧化程度，降低了清除自由基能力，加速植株衰老。由于重度胁迫、中度胁迫上述特性和对照差异显著，而轻度胁迫和对照差异不显著，可以认为轻度胁迫，即土壤含水量为田间持水量的６０％为小麦正常生长发育的下限指标，可做为制定节水栽培措施的理论依据。

ith the increase of water stress,the activity of superoxide dismatase (SOD) and catalase (CAT) decreased,while the content of malondiadehyde (MDA) increased in both flag leaf and root,the transition point of lipid peroxidation is in 14 days after anthesis.During this period,the heavier water stress is,the rapider SOD and CAT activity decrease and MDA content increase,root vigor and soluble protein in flag leaf and root decrease rapidly.The results will acdelerate the membrane lipid peroxidation,decrease the ability to remove free radical and accelerate plant senescence.Because of the significant difference between high water stress,middle water stress and control in above characteristics,and insignificant difference between light water stress and control,the light water stress (60%) can be as minimum index for normal growth and development of wheat.