Effects Of Sowing Date And Planting Density On Maize Yield And Quality Of Different Maize Varieties

Sowing date and density are the two main factors affecting corn yield and quality.Suitable sowing date and planting density are important guarantees for high yield and quality of corn.In this study,10 maize varieties were used as experimental materials.Two sowing dates and two densities were set in the field from 2017 to 2018.The effects of different sowing dates and planting densities on corn growth and development,dry matter accumulation,yield and yield components and LAI were studied.As well as the nutritional quality of grain and the quality of straw feeding,which were applicated to provide a theoretical basis for the efficient use of light and heat resources in Guanzhong area and the improvement of corn yield and quality.The main research results are as follows:1.The results of two-year yield showed that with the delay of sowing date,the yield of corn showed a downward trend.And the yield of spring maize was significantly higher than that of summer maize.As the density increased,the yield of maize showed an upward trend.The yield reached the highest at 82,500 plants/hm~2.Huamei 1 had the highest yield at 67500plant/hm~2 density,with the highest yield at 11678.9 kg/hm~2,while Xianyu 335 had the highest yield at 82500 plant/hm2 density,the highest was 12878.05kg/hm~2,and the yield of each maize variety at 82500 plants/hm~2 was 11.43%higher than the density of 67500 plants/hm~2.As the density increased,the number of effective panicles per unit area increased significantly,while the 100-grain weight and the number of kernels per ear decreased.2.There was a significant negative correlation between sowing date and dry matter accumulation.With the delay of sowing date,the dry matter accumulation per plant decreased,and the dry matter accumulation per plant decreased with the increase of density.The dry matter accumulation after anthesis decreased significantly with the delay of sowing date,and increased with the increase of density.The dry matter accumulation during silking-maturing period accounted for the largest proportion of total dry matter accumulation during the whole growth period of maize under high density(M2).Appropriate increase in density and early sowing were effective ways to prolong the accumulation of dry matter in corn and increase the accumulation of dry matter.3.Within the density range of 67500 plants/hm2-82500 plants/hm2,LAI of 10 maize varieties was significantly higher than that of low density,and LAI of different maize varieties varied with the increase of density.With the development of maize varieties,LAI increased first and then decreased at the turning point of silking stage.LAI remained at a high level from silking stage to milk ripening stage.To a certain extent,delayed sowing could significantly reduce leaf area index(LAI)and appropriate early sowing could produce a higher level of LAI.The SPAD value decreased with the increase of density pressure.The maximum value of the SPAD value in the spring sowing date occurred 25 days after silking.Under the summer sowing period,the SPAD value reached the maximum during the silking period,and the maximum value of the SPAD value appeared earlier with the delay of the sowing date.With the delay of sowing date and the increase of planting density,the plant height and ear height of maize plants increased.4.With the increase of planting density,the grain protein content decreased significantly,while the trend of starch,fat and PSFC content was more complicated,and the regularity was poor.The variety effects of protein,fat,starch and PSFC contents in 10 maize varieties were greater than that of density.The three most important nutrients of corn seed,including protein,fat and starch,were significantly affected by sowing date.Compared with summer sowing,the starch content of spring maize decreased significantly,while the grain fat and protein content increased significantly.5.Higher planting density was not conducive to the accumulation of neutral detergent fiber(NDF),acid detergent fiber(ADF)and crude protein(CP)in straw.The contents of NDF and ADF in straw increased significantly with the increase of planting density,while the crude protein content decreased significantly,which led to the decrease of corn quality.With the delay of sowing date,corn NDF and ADF increased to varying degrees,that is,with the delay of sowing date,the feed quality of each corn variety straw decreased.