Drought Stress On Fruit Quality And Sugar And Acid Metabolism Of Yellow Fruit Effect Of Enzyme Activity

This experiment adopts the mature from seven years of hanyuan Huangguogan(Citrus cultivar cv.Huangguogan)as the research material,CK(Control),LD(Light drought stress)and SD(Severe drought stress)were designed as the three treatments of the experimen.,the soil moisture content of each treatment was 70-80%,50-60% and 30-40% of the field water capacity.The effects of different degrees of drought stress on glycolic acid content,glycolic acid metabolisation-related enzyme activity and fruit quality of yellow fruit were studied to provide the theoretical basis for the production of Huangguogan.The result of research shows that(1)Different degrees of drought stress had a certain inhibitory effect on fruit size development,and the degree of its inhibition is positively correlated with the degree of drought stress,but the effect on fruit shape was not obvious.Light drought stress can effectively improve the soluble solids content,soluble total sugar content and sugar-acid ratio in the fruit of Huangguogan.However,under severe drought stress,the content of Vc,soluble solid and organic acid in the fruit of Huangguogan was greatly reduced.(2)Different degrees of drought stress differences from citrus fruit soluble sugar accumulation mainly occurred in late fruit development,light drought stress can increase the content of soluble total sugar and sugar components in fruit,while severe drought stress reduced the content of soluble total sugar,glucose and fructose in fruits to a certain extent.However,severe drought stress reduced the content of soluble total sugar,glucose and fructose in fruits to a certain extent,but promoted the accumulation of sucrose in fruits of Huangguogan.SS(sucrose synthase)synthesis direction,SPS(sucrose phosphate synthase)and AI(sucrose acid invertase)activity differences in fruit were the main reasons for the differences in sugar accumulation in fruit later stage of fruit development under different degrees of drought stress.Among them,SS synthesis direction is the key enzyme that causes the difference of soluble total sugar content in fruits under different stress treatments,while SPS and AI are the key enzymes that cause the difference of sucrose content in fruits under different stress treatments.(3)The difference of organic acid content caused by different degrees of drought stress occurred in the late stage of fruit development,the effects on the content of organic acid,citric acid and malic acid in the fruit of Huangguogan were negatively correlated with the degree of drought stress,the main acid groups that caused the difference in fruit organic acid content under different degrees of drought stress were citric acid and malic acid.In addition,the effect of different degrees of drought stress on the organic acid content of Huangguogan fruit is not completely determined by the accumulation of organic acid,but has a great correlation with the degradation degree of organic acid in the later stage.ACO(cis-aconitase)and NAD-IDH(isocitrate dehydrogenase)were the key enzymes that caused the difference in organic acid content between different degrees of drought stress,and the higher the degree of drought stress,the stronger the enzyme activity of the two enzymes,which is conducive to the degradation of organic acids in the fruit of Huangguogan.