水分临界期持续干旱胁迫对夏玉米光合生理与产量形成的影响

Effect of Continuous Drought Stress During Critical Period of Water on Photosynthetic Physiology and Yield Formation of Summer Maize

试验于2018年夏玉米生长季在临沂设施农业气象试验站自动控制遮雨棚内水分控制场进行,以郑单958(ZD958)为试材,在水分临界期(拔节-开花期)设计5个水分梯度控制试验,模拟研究干旱胁迫对夏玉米光合生理与产量形成的影响。结果表明:水分临界期持续干旱胁迫下,开花期夏玉米叶片叶绿素a含量、净光合速率、气孔导度、蒸腾速率、株高、叶面积、地上部干物重均降低,且干旱胁迫越重降低幅度越大,T5处理下上述要素分别较T1处理下降42.6%、75.5%、83.2%、65.1%、27.5%、18.2%和44.9%。随着干旱胁迫的加剧,叶片水分利用效率呈先增后降的变化趋势,且在轻度干旱胁迫时最高。持续干旱胁迫下,夏玉米叶、叶鞘获得的养分分配增多,茎、果实、根获得的养分供给减少,植株营养供给与分配的改变不利于夏玉米健壮生长,倒伏风险增加,影响产量形成。此外,持续干旱胁迫下,夏玉米秃尖比、双穗率升高,百粒重、理论产量大幅降低。

The experiment was conducted during the growth season of summer maize in 2018 in moisture control field of automatic control rain shelter in agriculture meteorological test station of Linyi.With‘Zhengdan 958’(ZD958)as test material,five-gradient water control tests were designed during the critical period of water(jointing to blooming stage).The effects of continuous drought stress on photosynthetic physiology and yield formation of summer maize in the critical period of water were simulated and studied.The results show that the leave chlorophyll a content,net photosynthetic rate,stomatal conductance,transpiration rate and plant height,leaf area,total dry weight above ground parts of summer maize at the flowering stage decreased under continuous drought stress during the water critical period,and the heavier drought stress was,the greater reduction was.The above elements under T5 treatment were 42.6%,75.5%,83.2%,65.1%,27.5%,18.2%and 44.9%lower than those under T1 treatment in turn.The water use efficiency of summer maize leaves increased firstly and then decreased with the intensification of drought stress,and it reached the highest under light drought stress.Under continuous drought stress,the nutrient allocation of maize leaves and sheaths increased,while the nutrient supply of stems,fruits and roots decreased,which wasn’t conducive to healthy growth of summer maize,the risk of lodging increased,and the yield formation was difficult.In addition,the continuous drought stress also caused increase of bald tip ratio and double spike rate of summer maize and significant decrease of 100-kernel weight and theoretical yield.