Effects of Seedlessness and Swelling Treatments Based on GA₃ and CPPU on the Fruit Quality of 'Shine Muscat' Grapes

Seedless treatments and swelling treatments are important measures to improve the marketability of grapes. This study aimed to determine the effects of different seedless and swelling treatment formulas on grape fruit quality by analyzing the differences in fruit quality and aroma component accumulation under different concentrations of GA₃ and CPPU mixture treatments for 'Shine Muscat' grapes, with a view to providing guidance for practical production applications.

Taking 'Shine Muscat' grapes as materials, A group (10.0 mg·L^-1 GA₃+1.0 mg·L^-1 CPPU), B group (25.0 mg·L^-1 GA₃+1.0 mg·L^-1 CPPU), C group (25.0 mg·L^-1 GA₃+3.0 mg·L^-1 CPPU), D group (50.0 mg·L^-1 GA₃+5.0 mg·L^-1 CPPU), X group (15.0 mg·L^-1 GA₃+3.0 mg·L^-1 CPPU) and water control (CK) were carried out for seedless treatments in six groups at full-bloom stage, respectively. 15 days after full-bloom, P0 (clear water), P1 (15.0 mg·L^-1 GA₃+3.5 mg·L^-1 CPPU), P2 (35.0 mg·L^-1 GA₃+3.5 mg·L^-1 CPPU), and P3 (55.0 mg·L^-1 GA₃+3.5 mg·L^-1 CPPU) were carried out for swelling treatments in three groups on group C treatment. The effects of different seedless treatment and swelling treatment formulas on the appearance morphological indexes, color indexes and aroma components of grape fruits were compared.

The seedless rate of fruits treated with different seedless methods was higher than that of the control group, with the D group treatment achieving a 100% seedless rate. In terms of fruit quality, the D and C groups had the highest grain weight, the largest diameter, the highest skin brightness, and the strongest storability. The B and C groups had the highest sugar accumulation and the most significant increase in the solid-acid ratio. Regarding aromatic substances, different seedless treatments increased the variety of aromas. The C group treatment increased the components of terpenes and aldehydes, adding layers to the aroma. In the post-bloom fruit swelling treatments, groups P2 and P3 significantly improved fruit quality, increased fruit diameter, and enhanced storability. The P2 treatment most notably increased skin brightness and saturation. Group P1 and P2 significantly increased sugar accumulation and reduced acidity. All three treatments reduced the concentration of aromas, with P2 showing a greater increase in aroma concentration, and expanding the fruit while preserving its aromatic diversity.

Applying 25.0 mg·L^-1 GA₃+3.0 mg·L^-1 CPPU during the full-bloom stage, with 35.0 mg·L^-1 GA₃+3.5 mg·L^-1 CPPU post-bloom 15 days later, could improve the seedless rate and expansion effect of 'Shine Muscat' grape fruits while enhancing the overall fruit quality.