干旱对玉米穗发育及产量的影响

Effect of drought on ear development and yield of maize

干旱作为影响玉米产量的环境因素之首,对玉米植株形态、物质积累、生理作用、性器官发育等方面产生影响,最终降低穗粒数、粒重,导致产量降低。以雌雄穗发育为研究重点,本文综述了不同时期干旱对雌雄穗性状及开花吐丝间隔期的影响。玉米开花前遭遇干旱,延缓雌雄穗发育进程,减少分化小花数,增加籽粒败育,导致穗粒数降低;抽雄吐丝期间遭遇干旱,导致雄穗抽出困难、吐丝延迟,使开花吐丝间隔期拉长,严重时导致花粉、花丝超微结构发生改变,影响玉米授粉、受精过程,最终导致秃尖形成,穗粒数降低;灌浆期遭遇干旱导致叶片早衰,光合产物积累不足,籽粒灌浆受阻,粒重降低,最终均会导致产量下降。从源库关系角度分析,玉米灌浆期前干旱导致玉米产量降低的主要原因是穗粒数降低导致的库强不足;而灌浆期干旱主要是叶片早衰等营养器官发育受阻,限制同化物的积累及转运,此时源不足限制了产量的增加。

Drought is the most important limitation to maize yield. Studies have shown that drought can affect plant morphology, dry matter accumulation, physiological processes and reproductive organ development, thereby decreasing grain weight and per-ear kernel. With a specific focus on the development of male and female organs, this paper reviewed the effects of drought on the development of reproductive organs and anthesis-silking interval. Drought before anthesis delayed tassel and ear development, decreased total spikelets and increased kernel abortion, thereby lowering per-ear grain number. Drought during tasseling and silking hindered tasseling, delayed silking and prolonged anthesis-silking interval. In addition, severe drought during tasseling induced ultra-structural changes in pollens and silk, which severely affected pollination and fertilization and eventually resulted in bald-heading and grain number reduction. Moreover, drought during filling stage triggered leaf senescence, low photosynthetate accumu-lation, limited grain filling, induced grain weight lowering and eventually yield reduction. In terms of source-sink relationship, drought before grain-filling reduced grain number in response to weak sink, eventually reducing yield. Drought during grain-filling stunted the development of vegetative organs such as leaf senescence, which hindered the accumulation and transport of assimilates. Thus, source restricted yield increase.