Effects Of Plant Growthregulators On Berry Enlargement And Quality Of Summer Black Grapes

Summer Black grape is characterized by seedless,high quality,and early maturation.However,the berry is very small under the natural growth condition,which would decrease the marketability.Plant growth regulators are often used in vineyard to enlarge the fruit.But the effect of swelling and fruit quality is influenced by the type of agents,the concentration and grape growth period,and is closely related to the local climate conditions.The aim of this study was to explore the effect of plant growth regulators on fruit enlargement and fruit quality of Summer Black grapes in Yangling area,and to screen out the best enlargement treatments.The experiment was conducted in 2016 in Yangling region,Shaanxi province.Summer Black grapes were used as the experimental material.Different combinations of GA_3,GA₃+CPPU and GA₃+TDZ were selected and used on Summer Black grapes.The enlargement effect,basic physical and chemical indexes,total phenol content,the peel texture,the texture characteristics of berries and the storage characteristics were determined and evaluated by fuzzy mathematics method.The main conclusions based on our research are as follows:?1?There were two obvious growth peaks in the whole development period of Summer Black grapes,of which growth and development trend showed double"S"curve.The first rapid growth period of berries was 10 d to 30 d after anthesis.During 30 d to 40 d the growth rate of longitudinal and traverse diameter slowed down,and then berries reached to the second rapid growth period.The berry longitudinal and traverse diameter was 22.89mm×20.85 mm at harvest.?2?The combination of three plant growth regulators had significant effects on fruit enlargement,and the overall excellent sequence was TDZ+GA₃ treatment combinations>CPPU+GA₃ treatment combinations>GA₃ treatments.Compared with the control,the three treatments decreased the content of grape tannin and total phenol.At the same time,the combination of TDZ+GA₃ treatments reduced the total anthocyanin content of the grape berries?3?The combinations of TDZ+GA₃ were superior to CPPU+GA₃ in terms of peel thickness and fruit hardness.The effect of 2 mg/L TDZ+40 mg/L GA₃ on fruit was the most significant,which were 1.24 mm?0.50 N?1.50 mJ?0.17 N/mm.In the fruit texture,the hardness,adhesion and chewiness of the grape were mostly influenced by the concentration of GA₃.The overall excellent order was TDZ+GA₃>CPPU+GA₃>GA₃.Among them,2 mg/L TDZ+40 mg/L GA₃ was the best treatment.?4?Fuzzy mathematics comprehensive evaluation showed that the combination of three kinds of plant growth regulators could significantly improve fruit quality of Summer Black grapes compared to the control.Among them the treatment No.23?2 mg/L TDZ+40 mg/L GA₃?showed the highest score with best effect.?5?In the comprehensive quality evaluation of fruit,compared with the control,the combination of different concentrations of TDZ+GA₃ could improve the storability of grape and reduce the natural grain rate of ear to a certain degree.The treatment No.23?2 mg/L TDZ+40 mg/L GA₃?owned more advantages.?6?Based on the above test results,the preliminary technical scheme for the enlargement of Summer Black grapes in Yangling area was obtained:4 mg/L GA₃ was used to dip the Summer Black grapes inflorescences during the period that the inflorescences were 10¹5cm and the buds completely separated but not flowering.Inflorescences were dipped with 15mg/L GA₃ at the end of flowering for fruit protecting.At 10 days after fruit protecting treatment,grape berries were treated with 2 mg/L TDZ+40 mg/L GA₃ for fruit enlargement.