膜下滴灌对新疆杂交棉群体光合性能、冠层结构和产量的影响

Effect of under-mulch-drip irrigation on canopy photosynthesis,canopy structure and yield of hybrid cotton in Xinjiang

在田间试验条件下,以杂交棉兆丰1号为试验材料进行了不同膜下滴灌量的试验,探讨滴灌水量对南疆杂交棉群体光合性能、冠层结构及产量的影响。结果表明：限量滴灌条件下棉田土壤水分亏缺,群体光合速率（CAP）和叶面积指数（LAI）降低,群体呼吸速率（CR）及CR占群体总光合速率的比例（CRP）在盛花期上升,进入盛铃期以后又迅速下降,叶片平均叶簇倾斜角度（MFLA）增大,散射辐射透过系数（TCDP）和直射辐射透过系数（TCRP）增加,对光能的截获率降低。过量滴灌促进杂交棉生长势强的特性发挥,造成棉株营养体过旺,群体叶源量（CLSC）较高,但生育后期CR上升快,CAPP最低,光合物质累积量虽较高,分配到生殖器官中的同化物较少,产量下降。适量滴灌棉株长势稳健,叶片生理机能优化,CAP增强,LAI上升快,且后期能保持较高的LAI水平,较小MFLA,较低的TCDP和TCRP,群体对光的截获率高,产量较高。研究同时表明南疆地区兆丰1号的适宜滴灌定额为3 000~4 125 m3/hm2,产量可达7 714.3~8 289.5 kg/hm2,据此提出了杂交棉较理想的群体光合特征和冠层结构指标。

To explore the effect of under-mulch-drip irrigation on canopy photosynthesis,canopy structure and yield formation of hybrid cotton planted in Xinjiang,an experiment with limited drip irrigation was carried out under field condition.The results were as follow： limited drip irrigation caused water deficiency in cotton field,reduced canopy apparent photosynthesis（CAP） and leaf area index（LAI）;under this treatment,the canopy respiration rates（CR） and the ratio of CR to total CAP were higher in fully flowering stage but fell rapidly in full boll stage.The limited drip irrigation increased leaf mean foliage inclination angle（MFLA）,transmission coefficient for diffuse penetration（TCDP） and transmission coefficient for radiation penetration（TCRP）,with low light interception rate;On the other hand,excessive drip irrigation promoted the over-rapid growth of hybrid cotton,canopy leaf source capacity（CLSC） and high dry matter accumulation.But CR increased rapidly at late growth stage,and CAP was at its minimum level,result in low yield.In the case of hybrid cotton,under appropriate irrigation treatment,CAP was higher,and LAI increased sharply.It maintained at a higher LAI level at late stage,so it had a steady growth and optimal leaf physiological function which led to higher yield.Studies showed that the suitable amount of drip irrigation for Zhaofeng-1 in South Xinjiang was 3 000-4 125 m3/hm2.Its corresponding yield was 7 714.3-8 289.5 kg/hm2.The ideal canopy photosynthesis characteristic and canopy structure targets of hybrid cotton were discussed.