将玉米产量形成过程视为一个系统,采用系统分离方法,逐级深入地研究受旱减产的机制。结果表明,水分胁迫下玉米减产的程度及其原因因胁迫时期而异。开花期水分胁迫减产最重,其次是雌穗小花分化期和灌浆期,拔节期则相对较轻。其可能机制是:开花期和雌穗小花分化期水分胁迫,玉米光合性能严重受损,减少光合产物对籽粒“库”的供应,导致“库”容量减小,进而影响籽粒灌浆和产量形成。灌浆期水分胁迫使光合性能受损,光合“源”的生产能力下降,直接影响到籽粒灌浆。拔节期水分胁迫使籽粒“库”形成受到一定阻碍,但由于后期仍维持较大的绿叶面积,使其粒重增加而得到部分补偿,故减产较轻。 The process of corn yield formation is regarded as a system, and the system separation method is used to study the mechanism of drought-reduced yield step by step. The results showed that the degree and reason of yield reduction of maize under water stress varied with the stress period. Water stress at flowering stage had the strongest yield reduction, followed by floret differentiation and grain filling stage, but lighter at jointing stage. The possible mechanisms are: water stress at the flowering and floret differentiation stages, severely impaired photosynthetic capacity of maize, and reduced supply of photosynthetic products to the “library” of grains, resulting in a decrease of “stock” capacity and hence grain filling and yield formation. Water stress during the filling stage impaired the photosynthetic capacity and decreased the photosynthetic “source” productivity, which directly affected grain filling. The water stress at jointing stage hindered the formation of grain “sink”, but due to the late still maintain a larger green leaf area, make its grain weight increase and get partial compensation, so the yield reduction is lighter.