Effects of Planting Density on Individual and Population Structure Characteristics and Yield of Winter Wheat under Rainfed and Limited Water Supply Conditions
In order to investigate the effects of density on individual and population structure characteristics and yield of winter wheat under rainfed and limited water supply conditions,a field experiment was carried out at Gaocheng Experimental Station,Shijiazhuang City during 2022-2023 season using JM22 wheat cultivar under four densities:which were 1.8 ×106(D180),3.0 × 106(D300),4.2 × 106(D420)and 5.4 × 106(D540)plants/ha.Two irrigation treatments for each density,which were no irrigation during the whole growth period(W0)and irrigated once at the jointing stage(W1).The influence of planting density and irrigation treatments on leaf area(flag leaf,top 2 nd leaf,top 3 nd leaf,top 4 th leaf),non-leaf green organs(ear,awns,stem sheath)area,leaf area index,non-leaf green organ area index,dry matter accumulation,photosynthetic active radiation interception rate,water use efficiency(WUE)and yield of winter wheat were studied.The results showed that the leaf area of each leaf layer and non-leaf green organs decreased with the increase of density.D300 treatment got the highest leaf area index and non-leaf green organs index,and significantly higher than that in D540.The contribution of post-anthesis dry matter to grain yield was more than 70％.Compared with D540 treatment,reducing plant density decreased the transfer of dry matter before anthesis,but increased the accumulation of dry matter after anthesis and its contribution to grain yield.With the increase of density,WUE increased first and then decreased,D300 treatment achieved the highest WUE.Specifically,the WUE of D300 was 1.2％-14.4％and 2.5％-12.7％higher than that of other densities under WO and W1,respectively.Compared with WO,W1 treatment increased the area of leaf and non-leaf green organs of different densities,delayed leaf senescence,and improved the photosynthetic active radiation interception rate of canopy.Ultimately,the grain yield increased by 28.1％-39.7％.Under the conditions of this experiment,D300 treatment increased the leaf and non-leaf green organ area,leaf and non-leaf green organ area index,canopy photosynthetically active radiation interception rate,post-anthesis dry matter accumulation and its contribution to final grain yield.The yield of D300 was 2.4％-6.6％and 0.3％-9.7％higher than that of the other densities under WO and W1,respectively,which was the optimal density in this study.
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