Regulation Effects of Line-Spacing Expansion and Row-Spacing Shrinkage on Dry Matter and Nutrient Accumulation and Transport of Summer Maize Under High Plant Density
[Objective]The aim of this study was to explore the effect of line-spacing expansion and row-spacing shrinkage on maize yield,dry matter and nutrient accumulation and transport under high-density planting conditions,and to clarify the optimal allocations of row-spacing,so as to provide the theoretical basis for the further increase of grain yield in Huang-Huai-Hai summer maize region.[Method]For two consecutive maize growing seasons in 2019-2020,under the planting density of 82500 plants/hm2,a field comparison experiment was conducted with 5 equidistant row,including 60 cm (B1),65 cm (B2),70 cm (B3),75 cm (B4) and 80 cm (B5),and 2 summer maize varieties,including Denghai 518 (DH518) and Denghai 605 (DH605).The effects of line-spacing expansion and row-spacing shrinkage on maize yield and its constituent factors,dry matter accumulation,distribution and transport,nutrient absorption and transport were studied,and the correlation between dry matter accumulation,nutrient absorption and yield was analyzed too.[Result]The increase of the yield of summer maize showed a trend of increasing first and then decreasing,reaching the extreme value under B4.In the 2-year experiment,the yields of DH518 and DH605 under B4 treatment increased by 9.59％ and 13.18％ on average compared with B1 treatment,respectively.The analysis of yield components showed that the yield of summer maize was affected mainly by the number of grains per ear,the grain number per spike of DH518 and DH605 increased by 8.30％ and 11.1％ under B4 treatment compared with B1 treatment,respectively.Line-spacing expansion and row-spacing shrinkage significantly affected the dry matter accumulation of maize plants after silking (R1),and the increase of trailing distance showed a trend of first increasing and then decreasing,which reached the maximum value under B4 treatment.Logistic regression equation was used to fit the growth curve,and it was found that the maximum dry matter accumulation rate of DH518 and DH605 under B4 treatment increased by 13.6％ and 16.3％ than that under B1 treatment,respectively,and the average growth rate increased by 15.9％ and 17.5％,respectively.Appropriate increase of planting row spacing could improve dry matter accumulation after R1,and dry matter transfered from vegetative organs to grain before R1.The accumulation of N,P and K in the two varieties increased first and then decreased.The N,P and K accumulation of DH518 in R1 and physiological maturity (R6) were increased by 5.2％-25.2％,9.8％-43.5％,3.5％-26.1％ and 6.3％-29.0％,9.6％-49.9％,and 8.5％-31.0％ compared with B1 treatment,respectively;DH605 increased by 6.0％-17.4％,5.7％-28.9％,5.2％-19.1％ and 7.6％-28.4％,8.7％-46.5％,and 6.6％-25.7％,respectively.The increase of row spacing significantly increased the volume of transshipment of N,P and K in the 2 varieties,and reached the extreme value under B4 treatment.The volume of transshipment of N,P and K in DH518 and DH605 under B4 treatment increased by 19.9％,39.3％,23.3％ and 14.6％,30.8％,24.9％ compared with B1 treatment,respectively.The correlation analysis of above-ground dry matter accumulation and N,P,K accumulation and yield in R1 and R6 showed that the dry matter accumulation and N,P,and K accumulation were significantly positively correlated with grain yield.[Conclusion]Under high density planting conditions,line-spacing expansion and row-spacing shrinkage improved the maximum and average dry matter growth rate of DH518 and DH605,and promoted nutrient translocation amount and contribution rate of accumulation nutrients after the R1 stage,synergistically,thus increased maize yield and fertilizer utilization.Considering yield,accumulation and transport of dry matter and nutrients,75 cm equal row spacing was beneficial to yield under the planting condition of 82500 plants/hm2 in Huang-Huai-Hai summer maize region.
line-spacing expansion and row-spacing shrinkagesummer maizeaccumulation and distribution of dry matternutrient absorption and transportyield
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