Abstract:

The paper aims to explain the effect of different concentrations of methyl jasmonate (MeJA) on coloration and quality of ‘Crimson Seedless’ grape, so as to provide reference for improving coloration and quality of grape berry in Turpan. Three different concentrations (20, 60, 100 mg/L) of methyl jasmonate (MeJA) were respectively applied twice to ‘Crimson Seedless’ grape before and at the beginning of coloring period. The color and quality indexes of fruits were determined during the harvesting period to analyze the differences of the indicators under different treatments; the fruit color index and quality index were evaluated by membership function method to determine the most appropriate application concentration. The results showed that anthocyanin content in the peel was significant increased and chlorophyll was decreased, and the coloration of grape berry was improved. The grape berry treated with methyl jasmonate (MeJA) had a higher a value (green-red chromaticity coordinates) and C value (chroma) and a lower L value (lightness) and b value (blue-yellow chromaticity coordinates), and the color of the fruit surface was improved. The application of MeJA significantly enhanced the berry length, berry diameter, berry mass, cluster mass, peduncle size, soluble solid content and titratable acid, and decreased fruit shape index. Excessive high concentration of MeJA could reduce peduncle pull and the storage and transportation performance, and cause high titratable acid content, while the anthocyanins content and coloring index were not significantly increased. However berries tended to wilting with low concentration treatment. 15 indicators related to the fruit quality were selected in the comprehensive assessment with membership function method, the fruit quality rank of the 4 treatments was 60 mg/L> 20 mg/L> 100 mg/L> CK. In summary, spraying 60 mg/L MeJA twice on ‘Crimson Seedless’ grape before and at the beginning of coloring period in Turpan can significantly improve fruit coloring and fruit quality.

Key words: methyl jasmonate, ‘Crimson Seedless’ grape, coloration of grape, fruit quality, comprehensive evaluation