春玉米叶片生长动态变化及其对种植密度的响应

选择紧凑型玉米品种郑单958、郑单18和中间型玉米品种中单9409、农大108,对其在不同种植密度下叶片的形态特征、出叶速度和功能期的动态变化进行了试验研究。结果表明,春玉米植株不同叶组的出叶速度、叶片长度、叶片宽度存在差异,且受种植密度的影响。随种植密度的增大,植株中下部叶片伸出时间延长,而上部叶组表现为先缩短后延长;下部叶片的长度呈增大趋势,但宽度呈下降趋势,中部叶片的长度和宽度均表现为降低,上部叶片在较低密度时,长度和宽度降低,较高密度时出现部分回升现象。春玉米叶片的长度、宽度与叶序存在明显的相关性。植株中部叶片的宽度和长度最大,其次为下部叶片和上部叶片,基部叶片最小。春玉米植株基部叶片的非功能期较短,其次为上部叶片,中部叶片和下部叶片的非功能期较长。随种植密度的增大,春玉米中部叶组的非功能期时间长度呈下降趋势。植株不同部位叶组的功能期长度存在显著差异,基本表现为基部叶组的功能期长度〈上部叶组的〈下部叶组的〈中部叶组的。种植密度对春玉米不同部位叶组的功能期均存在明显影响。

Dynamic Change of Leaf Growth in Spring Maize and Its Response to Planting Density

The dynamic changes of morphological characteristics, leaf emergence rates and functional period of leaves of two compact maize cultivars, Zhengdan 958 and Zhengdan 18, and two intermedi- ate-type maize cultivars, Zhongdan 9409 and Nongda 108 were studied under different planting density. The results showed that the emergence rates, width or length of leaves were different among different leaf-groups in spring maize and were markedly affected by planting density. With the increase of planting density rate, the emergence time of leaves in the middle and low leaf-groups prolonged, while the time needed by leaves in top leaf-groups was shortened firstly, then prolonged. The width or length of leaves in the middle part of maize stem was the biggest, followed by leaves in the top and low part of stem, and the leaves of basal leaf-group were the smallest. With the increase of planting density rate, leaf length increased and leaf width decreased in low leaf-group, while the width and length of leaves in middle leaf-group both decreased. The width and length of leaves in top leaf-group decreased in lower planting density, but increased under higher planting density conditions. The non- functional period of leaves in spring maize was different among leaf-groups. That of basal leaf-group was the shortest, followed by top leaf-group, and those of middle and low leaf-group were longer. The non-functional period of leaves in middle leaf-group obviously declined with the increase of plant density. Compared with intermediate-type maize cultivars, the non-functional period of leaves in compact maize cultivars shortened in a lower density stand. The functional period of leaves in spring maize was much longer than that of leaf in non-functional period. The functional period of leaves varied with leaf-groups （basal leaf-group〈top leaf-group〈low leaf-group〈 middle leaf-group）, and were greatly affected by planting density.