夏玉米不同生育期对水分胁迫的生理反应与适应

利用大型活动遮雨棚池栽对夏玉米进行了出苗后的全程水分控制试验研究,探讨了不同生育期夏玉米叶面积、根系活力、叶片膜脂过氧化以及保护酶超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性对不同水分胁迫的生理反应与适应。结果表明:轻度受旱在大喇叭口至抽雄初期对植株叶面积影响不大,但抽雄后直至灌浆中期,轻度受旱持续时间长了也会对叶面积造成较大的不良影响。而重旱胁迫在各生育时期对叶面积的影响更为不利。干旱胁迫下,夏玉米生育进程中保护酶SOD、POD和CAT活性基本呈现一致下降的态势,膜脂过氧化作用增强,从而引发细胞内膜系统直接受损,可能是干旱逆境下作物主要的生理反应。各生育阶段因受旱时间和强度的不同,三个保护酶活性下降及膜脂过氧化产物丙二醛(MDA)积累均表现不同,随干旱胁迫的推进,短时期内对某些保护酶有一定的激发效应,即在大喇叭口期SOD和POD的活性有所增加,但此效应维持不长,其后骤降。受旱时间越长,受旱程度越重,则保护酶活性越低,MDA积累越多。根系对土壤干旱胁迫甚为敏感,玉米拔节期根系活力下降就见端倪,随受旱的延长及加剧将更加促使根系老化,根系活力快速衰减。

Physiological responses and adaptation of summer maize(Zea mays L) to water stress during different growth periods

simulating experiment on the responses of maize(Zea mays) to different soil water stress levels was conducted by pond cultivation at neutral loam,meadow soil.The soil water levels were designed as three levels by relative water content(RWC): 75 %(control,full water supply or well-watered),55 %(moderate water stress) and 35 %(severe water stress) from maize seedling to maturity by controlling irrigation and the mobile rain shelter.The leaf area,root activity,membrane lipid peroxidation and activity changes of SOD、POD and CAT in summer maize leaves under different soil water levels and different growth stages were analyzed in this paper.The results indicated that Moderate water stress would not change significantly its leaf area from big flare to early stage of tasseling,however,it would seriously decrease its leaf area from tasseling to middle period of filling.Severe water stress would seriously affect its leaf area during different growth periods.Further,during different growth periods the activities of SOD、POD and CAT basically reduced and membrane lipid peroxidation increased under drought stress,then induced direct injury on cell membrane system,which may be main physiological responses of crop to drought adversity environment.Moreover,at various growth periods,the activity changes of three protective enzymes and MDA content were different due to different intension and duration of drought stress.The activities of SOD and POD enhanced at big flare period,and then greatly declined.The longer and more severe the drought stress is,the lower the activity of protective enzyme is;and the longer and more serious the drought stress is,the more the content of MDA is.Root system was very sensitive to soil water stress,and root activity decreased beginning at shooting period.Prolonged and severe drought made root system senesce greatly,and then root activity attenuated quickly.