Effects On Density On Individual Productivity And Yield Of Different Plant Types Corn

Selecting compact varieties and increasing the planting density are the main ways to improve the maize production at now. But different plant species have different optimum density. If the group too large, the individual growth inhibition, plant productivity reduced,eventually lead to lower group production. In order to explore the changes in plant productivity and its relationship with the population yield in different densities conditions,then providing a theoretical basis and technical support for the creation of high-yielding group of different types corn. It used compact and semi-compact 2 types and set different densities.According to analysis the agronomic characteristic、photosynthetic characteristics、dry matter accumulation and yield in the key stages of summer corn, and setting the no space competition density to determine the plant production potential to study the effects on density of per plant productivity and group yield of different types summer corn. The main conclusion are as follows:1. Semi-compact corn’s plant height was higher than compact in two years. There were differences between species variation with changes in the density of plant height, the same plant type varieties did not show the same law. Stem diameter decreased with density increasing, semi-compact decreased much. With increasing of density, the ear height increased, under 67500 plants ha and 82500 plants ha semi-compact were higher than the compact, but in 97500 plants ha compact were higher.2. With increasing density, leaf area reduced and leaf area index(LAI) increased,semi-compact was larger in 67500 plants ha and 82500 plants ha, density increased to 97500 plants ha, the compact was greater than the semi-compact. Light transmittance of ear and bottom layer reduced when density increased. Semi-compact’ light transmittance higher in67500 plants ha and 82500 plants ha in 2014, under 97500 plants ha compact higher. In 2015,under the three densities were characterized by compact light transmittance greater than semi-compact. SPAD reduced with the increasing of the density, semi-compact SPAD higher than the compact. In addition to xianyu335 and zhengda12’ P_n with density change law isdifferent in two years, the other four varieties’ P_n were reduced with the increasing of the density, semi-compact high in 2014, but compact high in 2015.3. Per plant dry matter accumulation decreased with increasing of the density, while dry matter accumulation improved. In 2014, semi-compact accumulated more biomass than compact; which different from 2015, under 67500 plants ha and 82500 plants ha semi-compact was larger, in the density of 97500 plants ha, compact larger. In flower period,with the increase of the density distribution of dry matter in stem sheath and leaf ratio increased, while in the reproductive organs reduced. When density was improved, ear number increased significantly, kernels per row and kernel weight were significantly decreased and ear rows increased not significantly. With the increasing of density, ear length、ear diameter and harvest index were reduced, and bald length 、 empty bar rate and RUE increased.Population grain yield of Shandan609 and zhengda12 were increased at first then decreased with the increasing of density in 2014, which achieved the maximum at density of 82500 plant ha, while other varieties were increased and achieved the maximum at 97500 plant ha.In 2015, population grain yield of all varieties performed the same trend that were increased at first then decreased with the increasing of density, which achieved the maximum at 82500 plant ha.4. According to the quadratic relationship between population grain yield and realization of individual productivity of two type corn, it showed compact achieved the highest population grain yield when individual productivity was 64.3%, whereas the semi-compact was 66.5%. The optimum density of compact and semi-compact varieties was 97400 plant ha and 97400 plant ha. The results showed, semi-compact performed well in terms of agronomic traits, photosynthetic characteristics and dry matter accumulation, and achieved higher grain yield than the compact in more rainfall years. But in low rainfall years, compact had advantage under large density, which maintained higher photosynthetic characteristics, higher dry matter accumulation, and higher yield than semi-compact.