Study On The Plant Density Effects On Compact Maize Morphology And Yield Components

The reasonable plant density is one of the most important methods to achieve high and stable grain yield in maize production. In this paper, three maize hybrids (CHANG DAN 52, ZHENG DAN 958, and XIAN YU 335) were used to studying the plant density effects on agronomic and yield characteristics, and furthermore the reasonable plant density were suggested. These results provided useful information for high yield of seed breeding and cultivation in maize. The specific results are as follows:(1) The suitable plant density for CHANG DAN 52 is 75,000 plants/ha, with grain yield of 17548.5 kg/ha. The regression equation between plant density (X) and grain yield (Y) is Y=-11808+ 7536.1X-500.48X2 (R2=0.8939).The LAI (leaf area index) is 5 ~ 6 and 4 respectively during the time of tasseling to kernel-waxy-ripe stage, and kernel-waxy to harvest stage. The rate of dry matter production is 521.3 kg /ha/day at tasseling to kernel-milky-ripe stage, 289.3 kg /ha/day at kernel-milky to kernel-waxy-ripe stage, and 165.0 kg/ha/day at kernel-waxy-ripe to harvest stage. The proportion of photosynthesis at economic yield forming stage to total photosynthesis is 72.0%. The average of net assimilating rate in whole growth period is 6.6 g/m2.d. The best yield components for CHANG DAN 52 are 75000 ears/ha, 684 kernel number, and 342.1g for 1000-kernel-weight.(2) The suitable plant density for ZHENG DAN 958 is 75,000 to 90,000 plants/ha, with grain yield of 13056.0 to 13526.0 kg/ha. The regression equation between plant density (X) and grain yield (Y) is Y=-9432.4+5544.4X-339.42X2 (R2=0.9440). The LAI (leaf area index) is 4.2 ~6.2 and 2.6 respectively during the time of tasseling to kernel-waxy-ripe stage, and kernel-waxy to harvest stage. The rate of dry matter production is 471 kg /ha/day at tasseling to kernel-milky-ripe stage, 351.4 kg/ha/day at kernel-milky to kernel-waxy-ripe stage, and 135.0 kg/ha/day at kernel-waxy-ripe to harvest stage. The proportion of photosynthesis at economic yield forming stage to total photosynthesis is 67.5%. The average of net assimilating rate in whole growth period is 7.2 to 8.3g/m2.d. The best yield components for ZHEN GDAN 958 are 75,000 to 88,200 ears/ha, 524 to 466 kernel number, and 332.0 to 329.0g for 1000-kernel-weight.(3) The suitable plant density for XIAN YU 335 is 75,000 plants/ha, with grain yield of 137145 kg/ha. The regression equation between plant density (X) and grain yield (Y) is Y=-5726.1 +4720.1X-294.98X2 (R2=0.9124). The LAI (leaf area index) is 4.0 ~5.2 and 2.6 respectively during the time of tasseling to kernel-waxy-ripe stage, and kernel-waxy to harvest stage. The rate of dry matter production is 623 kg /ha/day at tasseling to kernel-milky-ripe stage, 310 kg /ha/day at kernel-milky to kernel-waxy-ripe stage, and 165.0 kg/ha/day at kernel-waxy-ripe to harvest stage.The proportion of photosynthesis at economic yield forming stage to total photosynthesis is 66.4%. The average of net assimilating rate in whole growth period is 7.9g/m2.d. The best yield components for ZHEN GDAN 958 are 75,000 ears/ha, 538 kernel number, and 339.0g for 1000-kernel-weight.(4) Under different plant densities, grain yield of three, photosynthesis characters, dry matter production and agronomic traits of three hybrids were significantly different. The plant leaf area, LAI, LAD and plant grain yield were relatively higher under low plant densities, and these traits of individual plant were becoming lower when the plant densities were increased, while the trait values of population were enhanced.(5) The relationships between plant density and grain yield, plant density and photosynthesis, plant density and dry matter production, as well as plant density and agronomic traits were studied using three typical Compact Maize hybrids under five plant densities. The results provide useful information for maize breeding and production.