Effects Of Planting Density On Growth And Yield Of Different Maize Varieties

In this study, we investigated the effect of different planting densities ofmaize varieties on the agronomic traits, photosynthetic characteristics, drymatter accumulation, grain yield and yield contributed factors. Theconventional maize varieties Xianyu335and Jundan8of Changchun, Jilinprovince and two maize varieties—M1and M2provided by Monsantocompany of USA were tested for different planting densities. Five plantingdensities for these varieties were tested in this study, they were50000plants/hm~2,60000plants/hm~2,70000plants/hm~2,80000plants/hm~2and90000plants/hm~2. The study revealed the correlation between planting densities anddifferent traits index. The optimal planting densities for different maize varietieswere determined. The study provided the basis for the rational close planting inmaize production. The results were as follow:1. The effect of planting densities on the main agronomic traits of maizevarieties: As the density increases, the different varieties of corn plant height,ear height gradually increase and stem diameter decreased. Plant height andear height were positively correlated with planting densities, but stem diameterwas negatively correlated with planting densities.2. The effect of planting densities on the yield of maize varieties: Differentvarieties have the appropriate density range, All varieties had their optimalplanting densities. For Xianyu335, M1and M2, the yield reached the peakunder the planting densities of60000-70000plants/hm~2. The yield declinedwhen the densities of M2were more than70000plants/hm~2, but the trend wasslow. It was showed that the yield of M2could be improved when increasingwater and fertilizer.3. The effect of planting densities on yield contributed factors: panicles perunit area, single grains per spike and kernel weight affect the yield ofmaize.The bare plant rate increased as the planting densities increased.Single grains per spike and kernel weight decreased as the planting densitiesincreased. But the panicles per unit area increased as the planting densitiesincreased. The result showed the grain yield increasing came mainly from theincreasing in the effective panicles per unit area. 4. The effect of planting densities on ear traits: as the planting densitiesincreased, the ear length and the ear width gradually reduced, the baldgradually increased. These lead to the reduction of plant individual production.5. The effect of planting densities on photosynthetic characteristics: theplanting densities greatly affected photosynthetic characteristics of the fourspecies—Xianyu335,jundan8,M1,M2. As the planting densities increased, theleaf area per plant and chlorophyll content gradually declined, LAI andphotosynthetic potential gradually increased. The result indicated that theplanting densities affected these index mainly on the late growth stage andless on early growth stage.6. The effect of planting densities on dry matter accumulation: the drymatter accumulation showed the "S" curve in the whole growth process ofcorn.The dry matter accumulated slowly in the seedling stage and in thejointing stage. The population dry matter accumulation and the dry matteraccumulation per plant showed an upward trend in the big trumpet stage todough stage. the population dry matter accumulation under high plantingdensities was higher than that under low planting densities.The study researched the relationships between the planting densitiesand the agronomic traits, yield, yield components, ear traits, photosyntheticcharacteristics and dry matter accumulation of the different maize varieties.The study provides the scientific guidance for high-yielding cultivation of thevarious maize varieties and development of new maize varieties.