Effect Of Gibberellic Acid Application On Growth And Developmentof Rabbiteye Blueberry

As an important plant growth regulator,Gibberellinhas the functions of improving the fruit setting,inducing the formation of seedless fruit,regulating fruit ripening and delaying fruit tree anthesis.By using Rabbiteye Blueberries variety-Powderblue as the test material.this paper mainly studiedthe effects on the blueberry flowering date,leaf and branchescharacteristics,chlorophyll fluorescence,floral bud differentiation,number of inflorescence,fruit set rate,fruit ripening period,fruit quality characteristics,the endogenous hormones,soluble sugars,the starch content and the seedscharacteristics of spraying gibberellinsin different periods.Various experiments were carried out to explore the effect mechanism of gibberellins treatment on the growth and development of Rabbiteye Blueberries in different period in order to provide some basis for production practice.The results are as follows:1.Spraying gibberellins before anthesis had effects on the leafcharacteristics.Treatment of 50 mg/L gibberellins can significantly increase leaf chlorophyll content,Leaf area,the number and length of branches.At the first year,branches number increased by 15.2%,annual branches length increased by29.9%;In the second year,the basal branches length increased by 12.8%.It's thus clear that the treatmentof spraying 50mg/L gibberellinspromoted the vegetative growth of blueberry.Treatment of spraying 100 mg/L gibberellins can inhibit the content of chlorophyll,the diameter and length of basal branches.Compared with the control,the decrease were 11.0%?20.9%?41%respectively.2.After treatment of gibberellins,the chlorophyll fluorescence parameters F0 and Y?NO?values were lower than those in the control group,and Y?NPQ?and NQP values were higher than those in control group.Spraying 100 mg/L gibberellin made Y?NPQ?value up 121.3%than control,NQP value increased by 176.2%.3.Treatment of spraying gibberellins before anthesis can advance the blueberry flowering date.100mg/L gibberellin treatment made a single inflorescence flowers number is increased by 15.7%than control.4.The effects of spraying gibberellins before anthesis on the fruit setting rate,maturity,single fruit weight and vertical and horizontal diameter during fruit development were significant.Two kinds of gibberellin treatmentsall made fruit postharvest hardness fell down.5.Treatment of spraying gibberellins in summer can delay blueberry floral bud differentiation for10 days.Total number of flower bud decreased 18.8%compared with control.Gibberellinalso affects the content of endogenous hormones ABA,IAA,GA₄,and change the colour of blueberry.