新疆超高产棉花冠层光分布特征及其与群体光合生产的关系

Canopy light distribution and its correlation with photosynthetic production in super-high yielding cotton fields of Xinjiang,Northwest China

以新疆超高产棉田(皮棉产量在4000kg.hm-2以上)为研究对象,分析不同生育时期棉花冠层光分布、群体光合速率和干物质积累量的变化,研究不同产量水平棉田冠层的光环境变化特征及其与群体光合生产的关系.结果表明:超高产田盛花期到盛铃后期冠层上、中、下层光吸收率的比例为2:2:1,呈均匀分布,群体散射辐射和直射辐射透过系数分别为0.20～0.55和0.22～0.56,处于较适宜范围,中、下层叶片受光良好,冠层各层次叶片群体光合速率差异较小.与高产(3500kg.hm-2)和一般高产(3000kg.hm-2)棉田相比,超高产田在盛铃前期具有较高的叶面积指数和群体光合速率峰值,在初絮期和盛絮期的叶面积指数下降缓慢,群体光合速率峰值仍保持较高值,非叶绿色器官对产量形成的光合贡献增大,群体干物质积累量较高.在栽培过程中,调节冠层结构,使垂直方向上光辐射和群体光合能力分布均匀是确保棉花高效利用光能、实现超高产的重要途径.

Taking the super-high yielding cotton fields （lint yield I〉4000 kg . hm^2） in Xinjiang as the objects, this paper studied the canopy light distribution, photosynthetic rate, and dry matter accumulation at different growth stages, as well as the relationships between the characteristics of canopy light environment and the photosynthetic production. From full flowering stage to late full boiling stage, the light absorption proportion in the upper, middle and lower canopy layers in the super-high yielding cotton fields was 2 ： 2 ： 1, and the canopy transmission coefficients for radiation penetration and diffuse penetration were 0.20-0.55 and 0.22-0.56, respectively, being at reason- able level. The leaves in the middle and lower canopy layers could well accept light, and the leaf photosynthetic rate had little difference among different canopy layers. Compared with high yielding （3500 kg .hm^2） and generally high yielding （3000 kg . hm^2） cotton fields, super-high yielding cotton field had higher leaf area index and the highest canopy photosynthesis rate at early full boiling stage, and slowly decreased leaf area index, higher canopy photosynthesis rate, increased contribu- tion of non-foliar organs to photosynthetic production, and larger dry matter accumulation from early boll-opening stage to full boll-opening stage. In cotton cultivation, to adjust the canopy structure for the equidistribution of light and canopy photosynthesis capacity in vertical direction could be the