Effects Of Growth Regulator On Seedless And Berry Quality Of ’Sunshine Muscat’ Grape

China is the largest producer of table grapes in the world,and grape production takes a large proportion in China’s fruit market.Nowadays breeding seedless cultivars with larger size and stronger fragrance has become a tendency for grape breeding industry.In production,growth regulators are often used to induce the seedlessness for seeded cultivars.‘Sunshine Muscat’grape is favored by consumers for its beautiful cluster,flashy and clean berries,rich fragrance and unique flavor.The seedless induction for‘Sunshine Muscat’might be affected by regional,climate and other factors.At present,the grape planting industry in Guangdong is uprising,but there are few reports on the formula of‘Sunshine Muscat’grape seedless treatment.In this experiment,‘Sunshine Muscat’was used as the test material.GA₃,CPPU,TDZ and other reagent were used to induce seedlessness and expand the grape berry size.To explore the effects of different formulations,analysis is performed on pedicel hardening of‘Sunshine Muscat’grape.Based on principal component analysis,formulation suitable for the seedless treatment of‘Sunshine Muscat’grape in Guangdong Province was selected for improving the commodity value of the berry.The main results are as follows:（1）Gibberellin is the key growth regulator in the seedless treatment of‘Sunshine Muscat’.It has better effect when applied with cytokinin or streptomycin.If gibberellin and cytokinin（CPPU or TDZ）are used in combination with seedless at appropriate concentration.Even without streptomycin added,the formulation can compare to the Japanese commercial formula.（2）The second swelling treatment is very important for seedless fruit expansion;The combination of gibberellin with CPPU,6-BA or TDZ can promote seedless fruit expansion in the seedless treatment,in which the effect of TDZ is more significant,but the effect of high concentration（4 mg/L）can lead to fruit yellowing;The application of TDZ is more effective during seedless treatment;The effect of low concentration TDZ（within 1 mg/L）combined with CPPU was obvious;Adding ABA in seedless treatment showed no effects of weakening GA₃on fruit expansion.（3）The formula of Seedless swelling treatment can significantly affect the fruit characters of‘Sunshine Muscat’.GA₃can elongate the fruit and increase the fruit shape index,while cytokinin can facilitate lateral growth of the fruit and reduce the fruit shape index.Among them,TDZ showed the most effectiveness in reducing fruit shape index.（4）The ideal treatments should effectively increase total sugar content,reduce acid content,increase sugar acid ratio and improve flavor.The seedless and swelling treatments yield insignificant effects on tannin content.（5）The hardness of fruit and pulp may be decreased by using CPPU alone,but this was not observed when using GA₃alone or GA₃mixed with CPPU.The hardness of fruit and pulp can be significantly improved by the formula of 20 mg/L GA₃+0.5 mg/L TDZ+2 mg/L CPPU seedless treatment and 40 mg/L GA₃swelling treatment.（6）Different formulations of seedless swelling resulted in the thickening of cluster and petiole and the hardening of pedicel.GA₃is the main factor leading to the thickening and hardening of pedicel.Cluster and petiole thickening is due to the accumulation of not only xylem,but also the lignin and cellulose content in cell wall.With addition of streptomycin,“gaoshou”,ABA failed to inhibit the thickening of pedicel.To conclude,the technology for preventing pedicel from hardening needs further research and development.By comparing the effects of formula,we recommend that the seedless swelling formula of‘Sunshine Muscut’is:the seedless formula is treated with 20 mg/L GA₃+0.5-1mg/L TDZ+2 mg/L CPPU in full bloom period,and swelling treatment with 25-40 mg/L GA₃after 2 weeks.The effects of this formulation are not inferior to the Japanese commercial formula for the grapes seedless rate,swelling and flavor quality.