Abstract: Effect of different treatments of shading (glasshouse natural light, shading with one-layer shade net and two-layer shade net) on growth and the diurnal changes of photosynthesis in cucumber, pepper, tomato and eggplant was studied in glasshouse. The results indicated that dry matter accumulations of the four vegetables were greatly decreased by shading, and reduced most when shaded with two-layer shade net. Photosynthesis of cucumber, pepper and tomato was depressed at 9:00 under glasshouse natural light treatment. Moreover, the average whole-day photosynthetic rate was highest under one-layer shading treatment, the treatment with glasshouse natural light took the second place, and the photosynthetic rate was least when treated with two-layer shading. However, the photosynthetic rate of eggplant was glasshouse light treatment>one-layer shading treatment>two-layer shading treatment. The intercellular CO₂ concentration of four vegetables with different treatments was two-layer shading treatment>one-layer shading treatment>glasshouse natural light treatment. Thus, stomatal limitation might be one of the factors leading to the photosynthesis depression in glasshouse natural light, meanwhile, non stomatal factor causing the lower ability of the whole plant leaf cell in utilizing CO₂ was the main cause of the lower photosynthesis of two-layer shading treatment. Therefore, eggplant showed higher resistance to high light and high temperature stress.

Key words: shading, vegetables, dry matter accumulation, diurnal photosynthetic change