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作物产量形成的实质,是通过光合作用将太阳能转化为化学潜能贮存在经济器官部分。从这一角度出发,可以把作物的经济产量这样来表示:经济产量=生物产量×经济系数。也就是说,产量水平的高低,一方面取决于生物产量(干物质积累量)的高低,另一方面取决于分配到经济器官部分干物质比重的大小。由于作物生产主要是靠群体,因此,生物产量和经济产量的高低与密度大小有直接关系。如同许多作物一样,小麦丰产栽培中,合理密植是增产的中心环节。在<春小麦产量形成特点>一文中已经谈到,小麦单位面积产量取决于单位面积穗数和每穗粒重。这些产量构成因素的变化,与单位面积基本苗数(种植密度)有密切关系。在目前一般生产水平条件下,基本苗数由稀到密逐渐增大时,产量也由低到高逐渐增加。但密度增加到一定限度后,增产效应不显著,甚至下降。单穗粒重、每穗粒数和千粒重则随密度的增加而下降,其中穗粒数下降程度比千粒重明显。图1是根据一个
The essence of crop yield formation is the conversion of solar energy into chemical potential by photosynthesis in the parts of economic organs. From this perspective, we can express the economic output of crops in this way: economic output = biological yield × economic coefficient. In other words, the level of production, on the one hand, depends on the level of biomass production (dry matter accumulation), on the other hand, depends on the size of the proportion of dry matter allocated to economic organs. Since crop production mainly depends on groups, the level of biomass and economic output is directly related to the density. Like many crops, reasonable planting density is the key to yield increase in high-yielding wheat. As already mentioned in the paper, “The Characteristics of Spring Wheat Yield Formation,” the yield per unit area of wheat depends on the number of ears per unit area and grain weight per spike. The changes of these yield components are closely related to the basic seedling number (planting density) per unit area. In the current general level of production conditions, the basic seedling number from thin to dense gradually increased, the production also increased gradually from low to high. However, after the density is increased to a certain extent, the stimulation effect is not significant or even decreased. The grain weight per panicle, the number of grains per panicle and the grain weight per thousand decreased with the increase of the density, and the grain number per ear decreased more obviously than the grain weight of 1000. Figure 1 is based on one