关键词: 桑树, 桑树, 次生代谢产物, 1-DNJ, 甜菜夜蛾, 保护酶活性

Abstract: In order to investigate the suitable planting density of different maize plant types in Northern Anhui, erectophile type varieties‘Zhengdan 958’and‘Zhongdan 909’and medium-type varieties‘Longping 206’ and‘Nongda 108’were used to analyze the effects of different planting densities on leaf growth and grain yield. The results showed that the growth speed of expanded leaf was characterized by a trend of fast-slowfast-slow. Planting density had slight influence on the speed of leaf emergence among different leaf-groups, but significantly affected leaf phyllotaxis, width and length of the longest and widest leaf. The corn leaf area was not susceptible in the early growth stage for all the types, but decreased with the planting density increase in the middle and later growth stage, and its difference was little in high planting density. ANOVA showed that the grain yield was significantly different among different varieties and planting densities and interactions between varieties and planting densities. The accepted and best planting density of the four corn varieties, ‘Zhengdan 958’,‘Zhongdan 909’,‘Longping 206’and‘Nongda 108’, were 60000-75000 plants/hm2 and 67500 plants/hm2, 60000- 75000 plants/hm2 and 75000 plants/hm2, 60000- 75000 plants/hm2 and 60000 plants/hm2, 45000-60000 plants/hm2 and 52500 plants /hm2 in Northern Anhui.