追施氮肥时期对冬小麦旗叶叶绿素荧光特性的影响

在大田条件下,研究了不同追氮时期对小麦旗叶叶绿素荧光特性、光合速率及籽粒产量的影响.结果表明,拔节期追肥较起身期或挑旗期追肥,改善了小麦旗叶PSⅡ的活性(F_v/F_o)、光化学最大效率(F_v/F_m)、光化学猝灭系数(qP)、实际量子产量(ΦPSⅡ)及光合速率,降低了籽粒灌浆中前期非辐射能量耗散,有利于叶片所吸收的光能较充分地用于光合作用,提高了籽粒灌浆后期非辐射能量的耗散，减缓了叶片光抑制程度和衰老进程.拔节期追肥可显著增加穗粒数和千粒重，提高产量.

Effects of nitrogen topdressing at different growth stage on chlorophyll fluorescence of winter wheat flag leaves

With field experiment, this paper studied the effects of nitrogen topdressing at different growth stage on the chlorophyll fluorescence and photosynthetic rate of winter wheat flag leaves, and on the grain yield of the wheat. Compared with that at getting-up and flagging stages, nitrogen topdressing at jointing stage improved the PSII (Fv/Fo) activity, maximum photochemical efficiency (Fv/Fm,), PSII coefficient of photochemical fluorescence quenching (qP), actual quantum yield of PSII electron transformation (phiPS II), and photosynthetic rate of flag leaves, and made the dissipation of non-radiant energy lower at early and middle filling stage, and higher at late filling stage, which made it possible for flag leaves to absorb more light energy for photosynthesis at early and middle filling stage, and reduce the light inhibition extent and senescence at late filling stage. Nitrogen topdressing at jointing stag increased the spikes and grain weight per kernel, resulting in the highest grain yield.