Abstract:

In order to utility ALA in summer squash, we need a better understanding of the mechanism of ALA to photosynthetic and physiological characteristic of summer squash. Using ‘Zaoqingyidai’ as experiment material, an experiment was conducted to examine the effects of 5-aminolevulinic acid (ALA) on photosynthetic characteristics of leaves of summer squash seedlings under chilling stress. The results were as follows: Under chilling stress，the chlorophyll contents decreased, net photosynthesis rate (Pn), leaf area and dry matter of per seedling decreased greatly. ALA of 60 mg/L could relieve the effects of chilling on summer squash seedlings by increasing chlorophyll contents, photosynthesis rate, the leaf area and dry matter with 29.96%, 52.96%, 39.80% and 43.75% respectively. Because of increasing the chlorophyll contents and decreasing nonstomatal limitation effects, ALA of 60 mg/L could relieve some of the effects of chilling stress on summer squash seedlings.