苗期干旱及复水对玉米生长和生理特性的影响

Effects of Drought and Re-watering at Seedling Stage on Growth and Physiological Characteristics of Maize

采用盆栽控水试验,以水分敏感性不同的2个玉米品种创玉358和郑单958为试材,设置3个水分梯度:CK(正常供水,保持最大田间持水量的75%~80%)、MS(中度干旱,保持最大田间持水量的50%~55%)和SS(重度干旱,保持最大田间持水量的35%~40%),实施控水10 d后均恢复到正常供水水平并保持正常供水5 d之处理,研究苗期干旱及复水条件下玉米株高、单株叶面积、生物量、叶绿素相对含量、抗氧化酶活性、可溶性蛋白质含量、可溶性糖含量和脯氨酸含量的变化,探讨干旱胁迫及复水对玉米生长发育、抗氧化酶以及渗透调节物质的影响机制。结果表明:干旱胁迫抑制玉米生长,致使株高、地上生物量显著下降,胁迫程度越高降幅越大;相同胁迫下,创玉358降幅高于郑单958;复水5 d时中度干旱处理的株高、叶绿素含量、生物量都产生补偿效应,郑单958补偿效应更大。中度干旱处理主要通过SOD、POD和CAT的协同作用来清除活性氧,重度干旱处理清除活性氧的能力急剧降低;复水后主要通过保持较高的SOD、POD活性来有效清除活性氧。干旱胁迫提高玉米叶片中丙二醛含量,胁迫程度越大其含量越高;相同胁迫处理郑单958叶片中丙二醛含量低于创玉358,复水后干旱处理叶片中丙二醛含量降低。干旱胁迫提高玉米叶片中脯氨酸和可溶性糖含量,胁迫程度越大含量越高;相同干旱处理,郑单958叶片的可溶性糖和脯氨酸含量均高于创玉358;复水5 d后干旱处理玉米叶片中可溶性糖和脯氨酸含量均降低,重度干旱降幅大于中度干旱。

Two different water sensitivity corn Chuangyu 358 and Zhengdan 958 were used as the materials for the pot water control test,and three water gradients were set as CK(normal water supply,maintaining 75%~80%of the maximum field water holding capacity),MS(moderate drought,maintaining 50%~55%of maximum field water holding capacity),SS(severe drought,maintaining 35%~40%of maximum field water holding capacity),and all returned to normal water supply level after 10 days of water control and maintaining normal water supply for 5 days.Maize plant height,leaf area per plant,dry matter accumulation,relative chlorophyll content,antioxidant enzyme activity,soluble protein content,soluble sugar content and proline content were studied to explore the mechanism of drought stress and re-watering on maize growth,antioxidant enzymes and osmotic adjustment substances.The results showed that drought stress inhibited the growth of maize plants resulting in significant decrease of plant height and above-ground biomass.The higher the degree of drought stress was,the greater the reduction was.Under the same degree of water stress,the reduction of Chuangyu 358 was higher than those of Zhengdan 958.The plant height,chlorophyll content and biomass of the moderate drought treatment had compensation effects after re-watering for 5 days,and the compensation effect of Zhengdan 958 was greater.The MS treatment mainly used the synergistic action of SOD,POD and CAT to remove active oxygen and the SS treatment greatly reduced the ability of removing active oxygen.The active oxygen could be effectively removed by maintaining high SOD and POD activities after re-watering.Drought stress increased the malondialdehyde content in corn leaves,and the greater the water stress was,the higher the malondialdehyde content was in corn leaves.Under the same water stress condition,the malondialdehyde content of Zhengdan 958 leaves was lower than that of Chuangyu 358,and that in leaves under drought treatment reduced after re-watering.Drought stress increased proline content and soluble sugar content in corn leaves,and the greater the degree of water stress was,the higher the soluble sugar content and proline content were in corn leaves.Under the same water drought treatment,the soluble sugar content and proline content of Zhengdan 958 were higher than those of Chuangyu 358.After 5 days of re-watering,the soluble sugar content and proline content in corn leaves of drought treatments decreased,and the decreasing range of SS treatment was greater than that of the MS treatment.