【摘要】 玉米田的群体结构和光能分布随密度而异,与播方式的关系不大。就结构与光分布而论,以每亩3,000株的最为理想亦最有利于高产。玉米叶片的伸展方向,可以通过叶片的向光性来自动调节。更多还原

【Abstract】 (1)The population structure varies with the age and growth of the plant.The leafarea and dry matter increase greatly from the stage of node elongation to that of pollina-tion.During this period,the ears begin to grow fast.Organic matters are translocated tothe ears from other organs of the plant during time of pollination to maturity stage.Hence,the center of gravity of the population structure moves down to the middle part of the maizefields.In analyzing the results of the population structure,the vertical distribution of light,and the grain yields of the maize fields,it is found that a population of 3000 plants per mowis more reasonable than that of 2000 or 4000 plants per mow.(2)In the maize fields,the vertical distribution of light varies with the density of thepopulation structure.The transmission of light to the field decreases as the density of themaize increases.In case there is a population of 3000 or 4000 plants per mow,the leaf dis-tribution in the middle part of the maize fields is comparatively uniform,and so the verticaldistribution of light may well be represented by the Beer-Lambert equation.However,thesituation is different in the upper and the lower parts of the maize fields in that its leaf dis-tribution is not very uniform.In the fields of a population of 2000 plants per mow,the leafdistribution is far from being uniform even in the middle part,and so the Beer-Lambertequation is not applicable in this case.(3)The maize fields as well as other kinds of fields show a system of autoregulation.Both the area and the extending direction of the leaves vary with the planting density andthe irradiation of the population structure.This autoregulation is carried out through re-generation.更多还原