关键词: 春玉米, 密植, 化控剂, 光合特性, 叶片衰老, 产量, 乙烯利

Abstract: To explore the regulation mechanism of chemical regulator on photosynthetic characteristics and leaf senescence of spring maize under density-increasing condition,a field experiment was conducted using Zhengdan 958 (ZD958,compact type) and Liangyu 99 (LY99,semi-compact type) with chemical regulator( Gaoyubao, active ingredient was 40% ethephon) under different planting densities [52 500(D1),60 000 (D2),67 500 ( D3),75 000 (D4)plants/ha],and the effect of chemical regulator on photosynthetic characteristics, leaf senescence and yield of spring maize was studied under densityincreasing
condition.The results showed that spraying chemical regulator significantly reduced plant height and ear height of spring maize. The SPAD value of ear leaf also increased after spraying chemical regulator at silking and filling stages, which delayed leaf senescence. Spraying chemical regulator improved the photosynthetic performance of ear leaf, increased photosynthetic rate, transpiration rate,stomatal conductance, activities of antioxidant enzymes (peroxidase, superoxide dismutase) and key enzymes(nitrate reductase, glutamine synthetase)related with nitrogen metabolism, promoted nitrogen assimilation and metabolism of leaf,and delayed leaf senescence at late stage. For CK,the yields of ZD958 and LY99 increased first and then decreased with the increase of planting density;the yield of ZD958 was the highest under D3 density,and which of LY99 was the highest under D2 density. After spraying the chemical regulator,overall the yields of both two spring maize hybrids were the highest under D2 density.Thus,reasonable planting density combined with spraying chemical regulator could be an important technique for high-yield cultivation of spring maize in Northeast China.

Key words: Spring maize, Compact planting, Chemical regulator, Photosynthetic characteristics, Leaf senescence, Yield, Ethephon