栽培措施对棉花短季直播群体冠层结构和光合作用的影响

Effects of Cultivation Measure on Canopy Structure and Canopy Apparent Photosynthesis

在油后短季直播条件下,研究了种植密度、株行距配置、施氮水平对于棉花群体冠层结构和光合作用的影响。结果表明:中部和下部的光合有效辐射(PAR)值均随着生育期的推进呈现先下降后上升的趋势,且在吐絮期达到最高点。在盛蕾期和吐絮期,高密度群体的PAR值大于低密度群体;宽窄行处理比相同条件下的等行距处理的中部和下部PAR值高。施氮量对PAR值影响不显著。在生育后期的吐絮期,180 kg/hm2施氮量条件下的透光率相对最高,等行距处理比宽窄行处理的透光率高,说明该施氮量和等行距处理有利于维持生育后期较高的透光率。直射光率随着生育进程的推进整体呈上升趋势,各处理间变化幅度不大。密度、株行距配置和施氮量对群体盛蕾期和花铃期的净光合速率影响显著,对吐絮期影响极显著。高密度群体具有较高光合速率,宽窄行配置比等行距更有利于棉花群体维持较高的光合速率。

The field experiments on the planting densities,allocations of row-spacing,nitrogen application rate on the can-opy structure,canopy apparent photosynthesis and yield of cotton were conducted in Hunan.The results indicate that:the PAR fell and then increased with the process of growth period and was the highest during the boll opening stage.The PAR of the high density group was higher than that of low density group.The PAR of wide-narrow row spacing group was higher than that of equal planting spacing.During the boll opening stage,the transparency was the highest with the nitrogen appli-cation 180 kg/hm2.Equal planting spacing has relative higher transparency than wide-narrow row spacing.It showed that nitrogen application 180 kg/hm2 and equal planting spacing were good for maintaining higher transparency during the late period of duration.The transmissivity of direct light rate increased steadily with the process of growth rate.The planting density,allocations of row-spacing,nitrogen application rate had significant effect on the net photosynthetic rate of full squaring stage and full boll stage.The higher density canopy had relative higher canopy photosynthetic rate.Wide-narrow row spacing,compared with equal planting spacing,maintained at a relatively high level in photosynthetic rate.