Effect Of Planting Density On Water Consumption Characteristics Of Different Genotypes Of Summer Maize

The North China Plain is the most important summer maize production base in China,but the area is short of water resources.In order to balance the contradiction between summer maize production and water resource shortage,increasing summer maize planting density and selecting suitable genotypes are effective ways to improve water resource utilization efficiency.However,the coupling effect of different planting densities and genotypes on summer maize yield and water use efficiency is not clear.Therefore,this study has significant implications for ensuring food security and developing socio-economic development.This experiment was conducted at the Agricultural Experimental Station of Shandong Agricultural University during the summer maize growth period in 2021 and 2022.The experiment was conducted using a split plot design,with three planting densities of high(H,10.0 plants/m~2),medium(M,7.8 plants/m~2),and low(L,5.6 plants/m~2)as the main treatments,and two genotypes of Zheng Dan 958(Z)and Deng Hai 605(D)as the secondary treatments.There were six treatments in total,with each treatment repeated thrice,totaling 18 plots.The main purpose of this study was to determine soil water content,leaf area index,photosynthetic characteristics,dry matter accumulation,and yield,in order to explore the effects of planting density and genotype on photosynthetic characteristics,radiation use efficiency,water use efficiency,and yield of summer maize.The results show that:Under the same genotype treatment,with low density treatment as the control,high density treatment and medium density treatment can reduce the soil volume water content of the 0–60 cm soil layer during the jointing stage of summer maize.During the two years,the soil water content of the two genotype treatments in the 0–60 cm soil layer presented Zheng Dan 958 was lower than Deng Hai 605 during the large bell mouth stage,while Zheng Dan 958 was higher than Deng Hai 605 during the filling stage.Soil water storage increases with the increase of precipitation,while evapotranspiration increases with the increase of density.Increasing planting density increased the leaf area index,light interception rate,dry matter accumulation,and spike number of summer maize,but decreased chlorophyll content,net photosynthetic rate,transpiration rate,and 1000–grain weight.High planting density and low planting density are not conducive to improving radiation use efficiency and yield.The leaf water use efficiency of Zhengdan 958 was significantly increased by 19.45%compared to Denghai 605,but the radiation use efficiency of Denghai 605 was significantly increased by18.19%compared to Zhengdan 958.At the same density,the chlorophyll content index of Denghai 605 genotype was significantly higher than that of Zheng Dan 958,indicating that Denghai 605 had a higher conversion efficiency of photosynthetic effective radiation,making its dry matter accumulation at both high and medium densities significantly higher at maturity in 2021 than that of Zheng Dan 958.From jointing stage to silking stage,the radiation use efficiency of the two genotypes of summer maize under high density treatment was significantly higher than that under low density treatment;From the silking stage to the mature stage,the radiation use efficiency of Denghai 605 medium density treatment was the highest between two years,with 2.02 and 2.16 g/MJ,respectively.Genotype significantly affects the number of rows number per spike.Between two years,the number of rows number per spike of Zhengdan 958 was significantly reduced by 6.21%and 7.88%compared to the Denghai 605 treatment,respectively.Planting density significantly affects the number of spikes,kernel numbers per row,1000-kermel weight,and yield of summer maize.The number of spikes raises with the increase of planting density.The pattern of 1000-kernel weight and kernel numbers per row is consistent,and both decrease with the increase of planting density.The 1000-kernel weight is higher under low density treatment,but it cannot compensate for the decrease in the number of ears,so the yield of summer corn under low density treatment is lower.In addition,different planting densities have a significant impact on the water use efficiency of summer maize.Between two years,both genotypes showed the highest water use efficiency under medium density treatment,with the medium density treatment significantly improving water use efficiency by 21.70%compared to the lower density treatment.In conclusion,from the perspective of improving water use efficiency and yield of summer maize in the North China Plain,it is recommended to use Denghai 605 with a density of 7.8 plants/m~2.