Effects of Leaf Removal on Grain Filling and Yield of Summer Maize under High Planting Density

Huang Rundong; Dong Shuting; Liu Peng; Zhang Jiwang; Zhao Bin

doi:10.14083/j.issn.1001-4942.2017.11.005

Abstract：Increasing planting density is one of the important ways to improve grain yield of summer maize,but the canopy structure may be unreasonable under high planting density,which will influence the grain filling process and reduce grain yield.In this study,different leaf removal treatments were conducted to research the rules of grain filling characteristics and yield after changing the canopy structure of summer maize under high planting density.At the density of 105 000 plants per hectare,Zhengdan 958 and Xianyu 335 were used to research the effects of leaf removal on light transmission ratio,grain filling and yield by setting different treatments such as cutting two (L2),four (L4),six leaves (L6) and no leaf cutting (L0) from the top of plants at the 7th day after silking.The results showed that cutting leaves from the top of plants significantly improved the light transmission ratio of ear layer of summer maize at the 30th day after silking.But L4 or L6 led to serious light-leakage losses,which caused significant reduction of LAI in later period.While the LAI of L2 treatment was significantly higher than that of L0,and Zhengdan 958 and Xianyu 335 increased by 18.65％ and 28.56％ respectively.At the same time,leaf removal affected grain filling of summer maize under high planting density.Compared with L0,L2 treatment increased the grain volume significantly by 5.36％ and 6.29％ respectively for Zhengdan 958 and Xianyu 335.For Zhengdan 958 and Xianyu 335 under L2,the maximum grain filling rate increased by 6.19％ and 8.66％ respectively,while the average grain filling rate increased by 8.10％ and 9.35％ respectively.L2 treatment increased the weight of maximum grain filling rate (Wmax),prolonged the time of reaching the maximum grain filling rate (Tmax) and grain filling active period (P).For Zhengdan 958 and Xianyu 335,Wmax increased by 8.55％ and 10.92％ respectively,Tmax increased by 0.45 day and 0.59 day respectively,P increased by 0.63 day and 1.81 day respectively.Compared with L0,the grain dry weight at the 49th day after silking in L2 treatment increased by 8.10％ in Zhengdan 958 and 9.40％ in Xianyu 335.However,L4 or L6 treatments significantly decreased the grain volume and grain filling rate of two cultivars,reduced Wmax and Tmax and shortened P.At the same time,they led to the reduction of grain dry weight.For Zhengdan 958,the grain dry weight of L4 and L6 treatments at the 49th day after silking decreased by 8.34％ and 19.05％ respectively,and those of Xianyu 335 decreased by 7.46％ and 14.90％.Furthermore,cutting leaves from the top of plants under high planting density affected the grain yield significantly.Compared with L0,Zhengdan 958 and Xianyu 335 increased by 9.14％ and 9.92％ respectively under L2 treatment.While L4 and L6 treatments caused significant yield reduction.For Zhengdan 958,the grain yield of L4 and L6 treatments decreased by 17.22％ and 34.28％ respectively,and for Xianyu 335,it decreased by 21.13％ and 38.46％ respectively.The results showed that cutting two leaves from the top of maize plants under high planting density significantly improved the light condition of ear layer,prolonged the duration time of green leaf area,increased grain volume and grain filling rate and obtained a large grain dry weight,thus increased yield of summer maize significantly.