Zhang Mengyan et al. from Shihezi University and the Key Laboratory of Cultivation Physiology and Germplasm Resources Utilization of Characteristic Fruit Trees of the Army Group published an article entitled "Effects of exogenous ALA on fruit coloring and related enzyme activities of seedless grape Frei in solar greenhouse".

　　The experiment was conducted in Dapeng base of Beiquan Fruit Company of Shihezi General Plant. The effects of 5-ALA on fruit coloring and related enzyme activities of 5-year-old Eurasian grape variety Frei seedless were studied.

　　1, spray different concentrations of exogenous 5-ALA treatment

　　Effect on color parameters of grape fruit at maturity

　　As can be seen from the table, spray of exogenous 5-ALA at each concentration (50, 100 and 150ml/L) can significantly increase the fruit color index (GIRG), which increases by 16.9%, 30.9% and 19.6%, respectively, compared with the control group at fruit maturity stage. Significantly promote the color of grape fruit, improve the appearance of fruit color.

　　2, Spray different concentrations of exogenous 5-ALA treatment

　　Effect on the variation of grape fruit quality

　　As can be seen from the table, the change rule of total sugar content of seedless grapes of Frei after treatment with exogenous 5-ALA at different concentrations is as follows: During the fruit development process, compared with the control of each treatment (50,100,150 mg/L), the total sugar content of grape seeds presents a linear increase trend, of which 100 ml/L ALA treatment has the best effect. Compared with the control group, it increased by 24.8%. At the same time, it was found that exogenous 5-ALA treatment could effectively promote the accumulation of chlorophyll content in pericarp and alleviate the degradation rate of chlorophyll during fruit ripening. The effect was most obvious at 5 days after treatment, and the chlorophyll content of each treatment was increased by 53.3%, 52.9% and 50.9%, respectively, compared with the control.

　　3. Spray exogenous 5-ALA in different concentrations

　　Effects on the activity of anthocyanins and related enzymes in grape peel

　　As can be seen from the table, after spraying exogenous 5-ALA, each concentration can significantly promote the accumulation of anthocyanins in pericarp, and the effect is the most obvious at 15 days of treatment, with an increase of 49.4%, 62.2% and 49.3%, respectively, compared with the control, among which the overall effect of exogenous 5-ALA at 100mg/L concentration is the best. Although anthocyanins increased slowly until 25 days after treatment, exogenous 5-ALA treatment with 100,150 mg/L concentration still showed a higher promoting effect than the control.

　　The results showed that foliar spraying with different concentrations of exogenous 5-ALA could significantly increase the contents of soluble solid and soluble sugar in fruits, reduce acidity, improve fruit quality, and have a significant sweetening effect. The change of anthocyanin content maintained a good consistency, and the fruit color index (CIRG) was significantly increased at ripening stage, and the concentration effect still had a certain persistence after 25 days of treatment, and the concentration of 100mg/L had the best effect, and could effectively improve the internal quality and appearance of fruit color, and play a significant coloring effect