在塑料大棚内设置不同光照强度处理〔自然光(对照)、遮光40%和遮光60%〕,研究遮光处理对节瓜(Benincasa hispida Cogn.var. chiehqua How.)功能叶片光合特性的影响,结果表明节瓜叶片净光合速率(Pn)日变化呈单峰曲线,各处理在11:00达到峰值。节瓜Pn峰值随光照强度的减小而降低,叶片Pn达到峰值之前随遮光程度的增大而降低,而达到峰值之后,遮光40%处理的节瓜叶片Pn比对照高。叶片Pn的日变化幅度随遮光程度的增强而减小,叶片的光饱和点随光照强度的减小而明显降低。结果说明遮光处理通过影响环境因子和节瓜叶片生理特性等内在因素而影响其光合作用。塑料大棚内中午前后用遮光强度适宜的遮阳网覆盖,可提高节瓜功能叶片的光合能力,有利于提高产量。

Effectof shading(CK, 40% shading and 60% shading)on photosynthetic characteristics in functional leaves of Benincasa hispida Cogn. var. chieh-qua How. was studied in plastic greenhouse. The results indicated that change of the net photosynthetic rate(Pn)  of B. hispida var. chieh-qua in the daytime was one peak curve, the peak appeared at 11: 00 in all treatments. The peak values of Pn decreased with light intensity decreased. Before reached to the peak values, Pn decreased with shading degree increased, however Pn in 40% shading treatment was higher than that in CK after the peak appeared. The change range ofPn in the daytime and the light saturation point decreased with shading degree increased. The results showed that the effect of shading on photosythesis was due to the influences of shading on environment factor and physiological activity in B. hispida var. chieh-qua. It′s useful to increase Pn and yield of B. hispida var. chieh-qua with proper shading atnoon in greenhouse.