| Weibei highland of Shaanxi province was located in the middle and south Loess Plateau, and the photosource, heat, water and soil conditions were favor of making high and stable yield of maize. In recent years, the planting area of maize had continued to grow, and converted from traditional winter wheat growing areas to corn belt, so it became the main way to increase grain production in Weibei highland. In order to study the effects of planting density and different spring maize varieties on growth in Weibei highland, a field experiments of Yuyu22(plat leaf type), Zhengdan958(compact leaf type), Xianyu335(high planting density type) were conducted under different planting density [52 500 plants ?hm-2(D1), 67 500 plants?hm-2(D2), 82 500 plants?hm-2(D3), and 97 500 plants?hm-2(D4)] levels during 2013—2014 in Heyang, Shaanxi. Agronomic traits, RUE, WUE, yield and its components, and economic efficiency of maize were studied. The main results were as follows:1. Effects of different plangting density and varieties on agronomic traits of spring maizeWith increasing density, plant height gradually increased, stem diameter gradually reduced, the difference was not significant. Zhengdan958 showed a high yield character with dwarfing and stem diameter in 52 500~82 500 plants ?hm-2. In 67 500~97 500 plants?hm-2, Xianyu335 showed a stable yield character with plant height and stem diameter were no significant differences.2. Effects of different plangting density and varieties on RUE of spring maizeIn a certain density range, LAI increased with the increase of density; with the increase of density, micro environment in corn group was not good for corn growth and development, so, LAI declined with the increase of density in late growth stage; density had positive linear relationship to maximum LAI of Yuyu22, Zhengdan958, and Xianyu335. Accumulation of dry matter of spring corn in varying degrees of increase with the increase of density, the greater the density the less increase; under the same density treatment, dry matter accumulation of different varieties of spring maize were no obvious difference in the growth period; in the mature period, Zhengdan958 and Xianyu335 were higher than Yuyu22, and Xianyu335 had the highest dry matte accumulation in 97 500 plants ?hm-2 in two years. Chlorophyll content, light transmittance, photosynthetic rate and transpiration rate were decreased with the increase of density, but high density helps to form a larger green cover, increase LAI, increase the intercepting of light energy, so high density could improve the RUE, and Xianyu335 had the higher RUE in 82 500 plants ?hm-2 in two years.3. Effects of different plangting density and varieties on WUE of spring maizeWater consumption was mainly concentrated in the sowing to jointing stage and jointing to tasseling stage in its whole life period, and relatively small in the filing to maturity, Yuyu22 between low density(52 500 plants ?hm-2) and higher density(82 500 plants ?hm-2) had difference of 13.1 mm in two years, Zhengdan958 had difference of 16.5 mm, Xianyu335 between middle density(67 500 plants ?hm-2) and high density(97 500 plants ?hm-2) had difference of 14.0 mm, the final results was that the total water consumption had no significant difference under different density. Compared with the WUE in 52 500 plants ?hm-2, 67 500, 82 500, 97 500 plants ?hm-2 were increased by 10.81%, 14.19% and 15.00%, Zhengdan958(67 500 plants ?hm-2) and Xianyu335(82 500 plants ?hm-2) had the highest WUE respectively in two years.4. Effects of different plangting density and varieties on yield and economic efficiency of spring maizeYield components with different planting density had significant difference(P<0.05), ear number per hectare increased significantly with the increase of planting density(P < 0.05), while the grain number and 1000-grain weight reduced with the increase of planting density. Different varieties of spring maize yield response to high density differently, the increase production reduced with the higher density, there were even crop failure. Xianyu335 had the highest yield in 82 500 plants ?hm-2 in two years. The economic efficiency of different varieties was in different trends under different density, Xianyu335(82 500 plants ?hm-2) and Zhengdan958(82 500 plants ?hm-2) had the highest economic efficiency respectively in two years.In conclusion, Xianyu335 was growing well under 82 500 plants ?hm-2, improved the RUE and WUE of spring maize, increased corn yield and economic efficiency, so it is a more appropriate density and variety pattern for increasing both production and income in Weibei highland. |
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