水氮条件对温室黄瓜光合日变化及产量的影响

为研究温室内主要环境因子变化规律和黄瓜叶片光合日变化特征及其与产量的关系，在华北平原日光温室内设置了习惯和减量2个灌水处理，每个灌水处理下设3个施氮水平，共6个处理组合。结果表明：温室条件下光合有效辐射、温度、湿度等环境因子日变化均为单峰曲线；不同水氮条件下叶片净光合速率、气孔导度日变化曲线均呈双峰型，光合“午休”现象明显，气孔因素是主要限制因子；温室黄瓜光合速率与产量间呈二次曲线关系；适量的减水、减氮，黄瓜净光合速率下降不显著，而叶片瞬时水分利用效率则明显提高。当季的黄瓜以灌水5190 m3/hm2，施氮600 kg/hm2时（W2N40）具有较高的产量，这与习惯水氮处理相比，可增产4.21%。综合分析，优化的水氮处理（W2N40）不仅具有较高的净光合速率，瞬时水分利用效率，而且黄瓜产量高，是一种较为合理的水肥管理方式。

Effects of water and nitrogen conditions on the diurnal variation of photosynthesis and yield of cucumber in greenhouse

The major variation of greenhouse environmental factors and diurnal variation of photosynthesis of cucumber leaves and its relationship with yield were studied by designing different irrigation and nitrogen treatments in the greenhouse of North China. The results showed that the diurnal variation curves of PAR, Ta, RH and other environmental factors had a single-peak and the net photosynthetic rate and stoma conductance of cucumber leaves under different water and nitrogen conditions had two peaks. There was an obvious midday depression of photosynthesis and the stomata were the main limiting factors. The relationship between photosynthetic rate and yield of cucumber showed a quadratic curve. With moderately reduced water and nitrogen application rate, the net photosynthetic rate of cucumber did not decrease significantly, while the instantaneous leaf water use efficiency increased significantly. In our experiment, the highest yield was achieved with an irrigation quantity of 5190 m3/hm2 and nitrogen amount of 600 kg/hm2. Such practice can make the yield increase by 4.21 percent compared to the habitual water and nitrogen treatment. The general analysis showed that the optimization of water and nitrogen treatment resulted in a more rational management. This practice not only achieved a higher net photosynthetic rate and water use efficiency, but also a higher cucumber yield.