关键词: 大暴雨, 大暴雨, 多尺度特征, γ中尺度气旋

Abstract: To discuss the effects of different planting densities on yield and agronomic traits of wheat‘Bainong 418’, six different planting densities were set up: 2.25×106/hm2, 3×106/hm2, 3.75×106/hm2, 4.5×106/hm2, 5.25× 106/hm2, 6×106/hm2. In the experiment field, the potential of high yield and lodging resistance of‘Bainong 418’were studied. The results showed that, the spike number increased with the increasing planting density in a certain range, but then it decreased along with the i crease of planting density; there was a log curve (y = 259.3lnx -859.7) between planting density and spike number. The yield increased significantly at low planting densities, but with the increase of planting density, the increase of yield was not noticeable or even the yield reduced; and there was a parabolic function (y =5024+22.12x -0.022x 2) between planting density and yield. The effects of planting density on the three factors of yield were presented as: spike number >1000-grain weight > the number of seeds per spike; and with the growth of the planting density, the number of spikes significantly increased while the 1000-grain weight and the number of seeds per spike decreased. The results of path analysis showed that, contributions of the three factors to yield were: spike number >1000-grain weight >the number of seeds per spike. Taking into consideration the potential of high yield and the lodging risk,‘Bainong 418’should be sowed in clay loam on October 10 every year, and its planting density should be set at 4.5-5.25 × 106/hm2to ensure its high yield; and there will be high lodging risk if the planting density is beyond 5.25 ×106/hm2.