Abstract:

In order to clarify the effects of planting density on the grain filling characteristics, dry matter accumulation, yield and yield components of different maize varieties, in this study, the medium-high yield maize varieties ‘Yongyou 1573’ and ‘Yongyou 1593’ were used as experimental materials in 2021-2022, and three densities of 60000, 75000, 90000 plants/hm2 were set. The results showed that under different planting densities, the 100-grain weight showed a "fast increase-slow increase" rising trend, and the grain filling rate showed a single peak curve of "first increase and then decrease", and the peak filling appeared about 22 days after pollination. Increasing the planting density significantly reduced the theoretical maximum 100-grain weight (a), the maximum grain filling rate (Rmax), the average grain filling rate (Rmean) and the grain weight (Wmax) when the grain filling reached the maximum rate, and the yield per plant was significantly positively correlated with the 100-grain weight, the number of grains per ear, Wmax, Rmax and Rmean. After pollination, the dry matter accumulation of plants decreased with the increase of density, and the decrease of high density was more significant. The proportion of vegetative organs of plants in the early stage of filling was relatively large. The proportion of each organ of plants in the middle and late stage of filling was in the order of grain>stem sheath>leaf>ear axis>bract, and the contribution rate of stem sheath dry weight to grain yield was the largest. Increasing planting density reduced the ear length, ear diameter, grain number per ear and yield per plant of different maize varieties, and increased the bald tip length. The yield per unit area was the highest at the density of 75000 plants/hm2. There were differences among varieties. The 100-grain weight of ‘Yongyou 1573’ was less than that of ‘Yongyou 1593’, and the grain number per ear and yield per unit area were greater than the latter, indicating that the 100-grain weight and grain number per ear jointly affected the yield per unit area. This study provides theoretical basis for the selection of optimum planting density and the improvement of corn yield, and also has theoretical guiding significance for the realization of high efficiency and yield increase of summer corn in northern Henan.

Key words: corn, planting density, grouting characteristics, dry matter accumulation, yield