| Effects of different planting density on the photosynthetic characteristics and yield difference of different maize varieties in Weibei highland were investigated.The aim of this study was to reveal the response of maize varieties to the planting density,and to determine the suitable planting density to adapt to the precipitation resources.In 2015-2016,field experiments were carried out by using spring maize cultivar Yuyu 22,Zhengdan 958,Xianyu 335,and were setup four planting density treatments at D1(52,500 plants·ha-1),D2(67,500 plants·ha-1),D3(82,500 plants·ha-1)and D4(97,500 plants·ha-1).The change of photosynthetic characteristics,leaf area index(LAI),dry matter accumulation,yield,yield related traits,water use efficiency(WUE),resource use efficiency(RUE)of spring maize at different growth stages,as well as soil fertility effect were observed.The main findings showed as follows:(1)Changes of photosynthetic characteristics at tasseling stage and structure characteristics under different planting density and different variety types of spring maize.Chlorophyll content(Chl),photosynthetic rate(Pn)and transpiration rate(Tr)decreased with the increasing of planting density,while LAI increased.Pn decreased by 1.32 umolCO2·m-2·s-1,Tr decreased by 0.297 mmol·m-2·s-1 and LAI increased by 0.181 for each increase in density of 10,000 plants·hm-2.The stem diameter,and ear length of spring maize decreased with the increase of planting density.The ear length decreased by 0.86 cm,the stem diameter decreased by 0.09 cm for each increase in density of 10,000 plants·ha-1.The lodging rate of Yuyu 22 and Zhengdan 958 rather than Xianyu 335 increased with the decreasing of stem diameter.(2)Changes of grain yield and its components under different planting density and different variety types of spring maize.The number of productive ear was remarkably increased with the increasing of planting density,but the kernels per ear and 1,000-kernel weight were significantly decreased(P<0.05).The kernels per ear decreased by 45 and the 1,000-kernel weight decreased by 12 g for each increase in density of 10,000 plants·ha-1.The yield of three maize varieties was the highest at D2 density.In treatment D2,the yield of Yuyu 22,Zhengdan 958,and Xianyu 335 were 10.52,9.59,and 9.14 t·ha-1 in 2015,and 11.37,9.73,and 9.77 t·ha-1 in 2016 respectively.The average yield of three maize varieties were increased by 21.9%,19.5%,and 7.5% respectively within two years,when the density was increased from 52,500 plants·ha-1 to 67,500 plants·ha-1.The average yield of three maize varieties were decreased by 19.8%,15.4%,and 7.7% respectively within two years,when the density was increased from 67,500 plants·ha-1 to 97,500 plants·ha-1.(3)Changes of soil nutrient content under different planting density and different variety types of spring maize.Increasing the planting density increases the consumption of soil organic matter and total nitrogen.The trend of soil organic matter content in different varieties was different under different densities in 2015-2016,but the trend of the two years was the same.The soil organic matter content in the surface layer(0-20 cm)and the middle layer(20-40 cm)was significantly higher than that in the lower layer(40-60 cm).The 0-60 cm soil organic matter average content of Yuyu 22 was increased before decreased,Zhengdan 958 and Xianyu 335 were reduced with the increasing of planting density.The 0-20 cm soil organic matter average content decreased in surface layer by 0.44 g·kg-1 for each increase in density of 10,000 plants·ha-1.The 0-20 cm soil total nitrogen content decreased with the increasing of planting density,and in the different soil layers showed that: surface layer> middle layer> lower layer,and the difference of soil total nitrogen content in surface layer was significantly larger than that in middle and lower layers in 2015-2016.The soil total nitrogen contents(0-60 cm)of D1,D2,D3 and D4 density were: 0.64,0.63,0.65 and 0.58 g·kg-1 in 2015,and 0.90,0.91,0.94,0.86 in 2016 respectively.(4)Changes of WUE and RUE under different planting density and different variety types of spring maize.Yuyu 22 and Zhengdan 958 had the highest WUE at D2 density,but Xianyu 335 at D3 density in the maximum WUE in 2015.At the density of D1 to D3,the RUEs of Yuyu 22 and Zhengdan 958 increased with the increasing of planting density,and RUE began to decrease slowly at D4 density.The RUE of Xianyu 335 was D1 to D4 has been showed an increasing trend.RUEs of three varieties showed that: Yuyu 22> Xianyu 335> Zhengdan 958 in different densities in 2015 and 2016.(5)Changes of cost and return under different planting density and different variety types of spring maize.The average net income of Yuyu 22,Zhengdan 958,and Xianyu 335 were 9795,8767,8643 yuan·ha-1 in 2015,and 10224,8636,8835 yuan·ha-1 in 2016 respectively.The average net income of densities showed that: D2> D3> D1> D4,and the varieties showed that: Yuyu 22> Xianyu 335> Zheng Dan 958.At D2 and D3 density(6.75 and 82 000 plants·ha-1),the tested maize varieties have reached the highest yield and second highest yield.The optimum planting density can be determined by regression equation of yield,dry matter accumulation,WUE,RUE with the density.The highest WUE was observed at 72,600 plants·ha-1,the highest grain yield was observed at 74,000 plants·ha-1,While the highest RUE was measured at 84,700 plants·ha-1,the highest dry matter accumulation was measured at 85,500 plants·ha-1.However we sought after the largest economic yield,the grain yield decreased,and the population lodging rate increased linearly at high density.Therefore,we regarded the density(7.26—7.4 plants·ha-1)which the maximum WUE and the maximum yield corresponding to as the optimum planting density range.The optimum planting density of different variety types of spring maize in Weibei dryland was different.Yuyu 22 was 72,500 plants·ha-1,Zhengdan 958 was 74,000 plants·ha-1,and Xianyu 335 was 73,200 plants·ha-1.Yuyu 22 had high stability and high yield.The optimum planting density of different variety types of spring maize was to be 72,600—74,000 plants·ha-1.Low density was recommended for thin planting varieties,and high density was recommended for close planting varieties. |
PDF Full Text Request