水氮运筹对膜下滴灌棉花光合特性及产量形成的影响

Effects of water and nitrogen management modes on the leaf photosynthetic characters and yield formation of cotton with under-mulch drip irrigation

以不同基因型棉花品种为材料,在土柱栽培条件下研究膜下滴灌条件下水氮运筹方式对新疆棉花光合性能和产量构成的影响.结果表明:播前灌溉+盛花期前限量滴灌+盛花期后充分滴灌,并配合氮肥基施20%+追施80%的水氮运筹方式(W4N2)下,盛花期叶片叶绿素含量、气孔导度(gs)、净光合速率(Pn)、PSⅡ实际光化学效率(ΦPSⅡ)和光化学猝灭系数(qP)均显著低于全生育期常规滴灌处理,非光化学猝灭系数(NPQ)增加,地上部干物质累积量受到限制;盛铃期至吐絮期叶绿素含量、gs、Pn、ΦPSⅡ、qP均随水氮供应量的提高而增大,地上部干物质产生超补偿积累,且有利于光合产物向棉铃的运转与分配.在氮肥基施20%+追施80%的施氮方式下,新陆早13号以播前灌溉+全生育期常规滴灌(W3)处理的籽棉产量较高,新陆早43号以播前灌溉+盛花期前限量滴灌+盛花期后充分滴灌(W4)处理籽棉产量最高.因此,在播前灌溉条件下适当减少盛花期前、增加生育中后期水氮供应,可以延长冠层叶片光合功能期,促进光合物质优先向生殖器官分配,充分发挥膜下滴灌棉花的增产潜力.

Taking different genotype cotton varieties as test materials,a soil column culture experiment was conducted to study the effects of water and nitrogen management modes on the photosynthetic characters and yield formation of cotton with under-mulch drip irrigation in Xinjiang,Northwest China.Under the management mode W4N2,i.e.,pre-sowing irrigation ＋ limited drip irrigation before full-flowering ＋ abundant drip irrigation after full-flowering in combining with basal 20% N ＋ topdressing 80% N,the chlorophyll content,net photosynthetic rate（Pn）,stomatal conductance（gs）,actual photochemical efficiency of photosystemⅡ（ΦPSⅡ）,and photochemical quenching coefficient（qP） at full-flowering stage all decreased significantly,the non-photochemical quenching（NPQ） increased,and the aboveground dry matter accumulation was inhibited,as compared with those under common drip irrigation.From full-flowering stage to boll-opening stage,the chlorophyll content,gs,Pn,ΦPSⅡ,and qP increased with increasing water and nitrogen supply,and the aboveground dry matter accumulation was enhanced by compensation,which benefited the translocation and distribution of photosynthates to seed cotton.Under the fertilization mode of basal 20% N ＋ topdressing 80% N,the seed cotton yield of Xinluzao13 was the highest in treatment pre-sowing irrigation ＋ common drip irrigation（W3）,but that of Xinluzao43 was the highest in treatment pre-sowing irrigation ＋ limited drip irrigation before full-flowering ＋ abundant drip irrigation after full-flowering（W4）.It was concluded that under the condition of pre-sowing irrigation,to appropriately decrease the water and nitrogen supply before full-flowering stage and increase the water and nitrogen supply at middle and late growth stages could extend the active photosynthesis duration and promote the photosynthates allocation to reproductive organ,which would fully exploit the yield-increasing potential of cotton with under-mulch drip irrigation.