玉米某些生理指标的日变化

对盛花期玉米紧凑型品种“四密25”、平展型品种“吉单159”不同密度、不同叶层的比叶重（SLW）、可溶性糖含量和含水量的日变化进行了测定。结果表明：玉米SLW、叶片和味鞘可溶性糖含量的日变化呈单峰曲线，12：00至14：00时最高。SLW可溶性糖含量随密度增加而下降，“四密25”的降幅小于“吉单159”。SLW和叶片可溶性糖含量均为上层＞中层＞下层，可溶性糖含量为茎秆＞叶鞘＞叶片。玉米叶片含水量早晚高、中午低，呈“V”字型变化，密植＞稀植，下层＞中层＞上层。

Diurnal Variation of Soluble Sugar, Specific Leaf Weight and Water Content Maize

Diurnal variation of soluble sugar, specific leaf weight (SLW) and water content under different plant density and at different leaf layers of Maize Simi25 and Jidan159 were measured during heading stage. The results showed that diurnal variation of SLW and soluble sugar took on a single-peak curve, and the maximum value was discovered from 12:00 to 14:00.It decreased with the increase of plant density, and change of Jidan159 was more obvious than that of Simi25. Content of SLW and soluble sugar was highest in the upper layer leaves, then coming second and third were that in the middle layer leaves and that in the lower layer leaves.Content of soluble sugar in stem was higher than that in leaf sheath , which in turn was higher than that in leaf.Diurnal variation of water content in maize is a V-shaped curve. It increased progressively with the decrease of the leaf height.