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玉米早期籽粒建成过程中干旱胁迫会导致果穗顶部籽粒的败育,使穗粒数降低,进而减少玉米产量。为探明干旱胁迫对玉米籽粒生长发育影响的生理机制,利用旱池控水和控制授粉技术,在授粉后前10d设置轻度干旱、中度干旱和正常供水3个处理,研究了2个玉米品种统一完全授粉和底部不授粉植株籽粒生长和光合特性等。结果表明,干旱胁迫使玉米的光合速率(Pn)和叶绿素相对含量(SPAD值)显著降低,复水后二者均恢复到正常。干旱胁迫降低了植株干重、穗重和穗粒重,水分胁迫期间植株干重的降低幅度相对明显。干旱胁迫使统一完全授粉处理玉米顶部籽粒干重和体积分别在授粉后12～16或16d显著或极显著下降,最终表现为败育或灌浆不充实,导致籽粒干重和体积的显著降低。而底部不授粉玉米由于从根本上阻止了底部籽粒的生长,确保了中上部籽粒有相对充足的同化物供应,干旱胁迫处理顶部籽粒生长发育正常。说明籽粒建成初期需要光合产物的持续供应,干旱胁迫通过降低同化物生产而增大了籽粒败育与生长不良的可能性,同化物供应不足是干旱胁迫诱导玉米籽粒败育和生长不良的根本原因。
Drought stress during early kernel formation in maize leads to abortion of the top grain of the ear and reduces the number of grains per ear, thereby reducing maize yield. In order to explore the physiological mechanism of drought stress on the growth and development of maize grain, we used 3 treatments of light drought, moderate drought and normal water supply in the first 10 days after pollination to control the pollination of two maize Uniform and complete varieties of pollination and the bottom of non-pollination plant grain growth and photosynthetic characteristics. The results showed that the photosynthetic rate (Pn) and the relative content of chlorophyll (SPAD) of maize decreased significantly under drought stress, and both returned to normal after rewatering. Drought stress reduced plant dry weight, panicle weight and grain weight per spike, and the decrease of plant dry weight during water stress was relatively obvious. Under drought stress, the dry weight and volume of the top grain of corn were significantly or extremely significantly decreased at 12-16 or 16 days after pollination, respectively, and eventually aborted or insufficiently grouted, leading to a significant decrease of dry weight and volume of kernel. However, the non-pollinated corn at the bottom prevented the growth of the bottom grain at the root, ensured the supply of adequate assimilates in middle and upper grain, and the growth and development of top grain under drought stress was normal. The results showed that the initial supply of photosynthetic products was needed in the early stage of grain filling. Drought stress increased the possibility of abortion and poor growth of maize by reducing the production of the assimilate. The deficiency of the assimilates was the basic reason of the abiotic stress and poor growth of maize induced by drought stress .