Effects Of Two Plant-growth Regulators On Physiological Characteristics And The Sugar-acid Components Of Blueberry

In this study,semi high bush blueberry‘Northland’and north high bush blueberry‘Boni’were used as experimental materials,the aim of this study was to investigate the effects of GA₃ and CPPU combination treatments on the internal and external quality of blueberry fruit,photosynthetic fluorescence properties of blueberry leaves,and the sugar-acid components of the fruit.In order to screen out the most suitable hormone concentration for the growth and development of blueberry,and provide scientific basis for blueberry production and cultivation management.The test results are as follows:1.Spraying different concentrations of GA₃+CPPU at the early flowering stage,full flowering stage,flowering stage and fruit enlargement stage had an effect on the internal and external quality of blueberry fruit.Spraying 100+5mg/L GA₃+CPPU during the fruit enlargement period significantly improved the internal and external quality of‘Northland’and‘Boni’fruits compared with other treatments.Compared with the control,the single fruit weight increased by 34.0%and 37.4%,respectively;fruit hardness increased by 47.3%and 27.3%,respectively.Soluble sugar content increased by 15.6%and 45.1%respectively.Soluble protein content increased by27.6%and 13.0%,respectively.The content of vitamin C increased by 14.4%and13.0%,respectively.The titratable acid content decreased by 19.4%and 18.1%,respectively.In addition,spraying 100+5mg/L GA₃+CPPU significantly increased the content of endogenous hormones ABA and ETH,and decreased IAA content.Spraying different concentrations of GA₃+CPPU at different times had no significant effect on the fruit setting rate of blueberry fruit.2.Spraying different concentrations of GA₃+CPPU at fruit expansion stage significantly increased chlorophyll content and photosynthetic characteristics of blueberry.When spraying 50+5mg/L and 100+5mg/L GA₃+CPPU at the fruit expansion stage,compared with the control,the chlorophyll a content of‘Northland’increased by 11.9%and 15.1%,respectively.The chlorophyll b content increased by37.5%and 41.7%,respectively,and the chlorophyll a+b content increased by 11.5%and 16.0%,respectively.When spraying 100+5mg/L GA₃+CPPU,compared with the control,the chlorophyll a content of‘Boni’increased by 26.3%,the chlorophyll b content increased by 21.0%,and the chlorophyll a+b content increased by 43.4%.Spraying different concentrations of GA₃+CPPU combination treatment can affect the OJIP curve,PSII receptor side and photosynthetic performance index of blueberry leaves to varying degrees.When spraying 100+5mg/L GA₃+CPPU,compared with the control,the relative variable fluorescence of‘Northland’leaves at J point and I point decreased by 22.0%and 7.1%,respectively,and the quantum yield for electron transfer increased by 22.2%.The relative variable fluorescence of‘Boni’leaves at J and I points decreased by 16.9%and 7.4%,respectively,and the quantum yield for electron transport increased by 21.1%.When 100+5mg/L GA₃+CPPU was applied,the number of active reaction centers in blueberry leaves increased,and the energy during electron transfer increased,thus improving the photosynthetic capacity of blueberry plants.3.Spraying different concentrations of GA₃+CPPU at fruit expansion stage had different effects on the content of the sugar-acid components in blueberry fruit.When100+5mg/L GA₃+CPPU was applied,the fruit glucose content of‘Northland’and‘Boni’increased by 22.3%and 16.4%,respectively,compared with the control.The fructose content increased by 40.8%and 20.1%,and the sucrose content increased by 36.3%and 9.4%,respectively.The citric acid content decreased by 36.4%and4.2%,respectively.The malic acid content decreased by 11.6%and 15.7%,respectively.The contents of fructose,glucose and sucrose in‘Boni’were higher than those in‘Northland’,and the content of malic acid was also higher than that in‘Northland’.