氮肥施用前移对遮荫下棉花光合特性及产量的影响

为探讨新疆南疆地区果棉间作下棉花适宜的氮肥追施模式,设置不施氮肥(N0)、氮肥追施至初花期结束(N1)、氮肥追施至盛花期结束(N2)和正常追肥(N3)。结果表明:遮荫下氮肥追施至盛花期结束(N2)提高了棉花盛花期后主茎功能叶潜在活性(Fv/Fo)、最大光化学效率(Fv/Fm)和光化学猝灭系数(q P),有利于光合色素将捕获的光能以较快的效率及速度转化成化学能,为碳同化提供更加充足的能量;同时增加棉花花铃期PSII开放程度和光合电子传递速率(ETR),促进实际光化学效率(ΦPSII)和净光合速率的提高,降低了初花期非辐射能的耗散,可将捕获的光能更充分地进行光合生产,提高了花铃后期非辐射能的耗散,可为棉铃输送较多的光合产物,增加了单株铃数和铃重,提高了产量。

The Effects of Nitrogen Topdressing on Cotton Photosynthetic Indices and Yield

To determine a suitable nitrogen topdressing mode for fruiting cotton and cotton intercropping in southern Xinjiang, China, the effects of four nitrogen topdressing modes were examined: no nitrogen (N0), nitrogen topdressing at the initial flowering stage (N1), nitrogen topdressing at the full flowering stage (N2), and normal topdressing (N3). Improvements in Fv/Fo(potential activity), Fv/Fm(maximum photochemical efficiency), and qP(photochemical quenching coefficient) were observed for main-stem leaf function with N2 under shade conditions. N2 also proved more efficient when examining photosynthetic pigment capturing of light energy efficiency and conversion, carbon assimilation, photosystem II (PSII) openness, and the electron transport rate at the flower and boll stage. Additionally, ΦPSII and the net photosynthetic rate were promoted, non-radiant energy dissipation was reduced at the initial flowering stage, and photosynthetic yield was higher under N2 conditions. In addition, we observed higher non-radiant energy dissipation at the late flower and boll stage and more photosynthetic product conveyed to cotton bolls, as well as higher boll numbers per plant, boll weight, and yield. These data suggest that nitrogen topdressing of cotton plants at the full flowering stage merits further attention.