Studies On Increasing The Sugar Content And Reducing The Organic Acid Content Of Huangguogan Fruit In Shimian

Take the Citrus cultivar cv. Huangguogan which is the natural hybrid and late-maturing citrus variety as the test material. Aimed at the poor quality of the high acid and low sugar from Shimian Huangguogan, we have carried out a series of studies about the sugar and acid metabolism in the fruit and the different treatments of potassium and phosphoru fertilizer on the quality of acid and sugar during the development of fruit in Huangguogan, to find out the optimal potassium and phosphoru fertilizer ratio, and gaining the nutrition diagnostic criteria from the point of view of potassium, phosphorus nutrition to provide a theoretical basis for the technical of adding sugar and reducing acid. The result shows that:(1)With the continuous growth of the fruit, the soluble sugar content, sugar-acid ratio and organic acid content of the fruit showed different trends during the development of fruit in Huangguogan, all of which are rising in the young fruit period. After entered the fruit enlargement period, the soluble sugar content and sugar-acid ratio increased rapidly, a sharp decline in organic acid content, with the coming of the fruit coloring period, the soluble sugar content and sugar-acid ratio remained the slow upward trend, but the organic acid content remained slow decline until when the furit ripend.(2) With the soluble sugar content increased in Huangguogan fruit, the activity trends of the sucrose metabolizing enzymes are different, AI and SS decomp keep dropping, but NI, SPS and SS composite are drop-ascend-drop, ascend-drop, ascend-drop. So AI and SS play a key role of the soluble sugar accumulation in the early stage of Huangguogan fruit development, but NI and SS composite in the mid and late stage, SPS in whole stage.(3)The organic acid metabolizing enzymes showed different trends in Huangguogan development fruit. The organic acid synthesis enzyme includes CS, PEPC and MDH, all of which are the same trend, that is ascend-drop; The organic acid degradation enzymes includs ACO and IDH, the trends of which are different:the ACO activity in the mitochondria is drop-stable, the ACO activity in the cytoplasm is ascend-drop, the IDH activity is ascend-drop-ascend. Taked the analysis of the organic acid metabolizing enzymes and the organic acid concent,we found CS is the key enzyme in the early stage of Huangguogan fruit development,both of ACO(cytoplasm) and IDH are the key enzymes in the late stage of Huangguogan fruit development.(4) Different potassium and phosphorus application treatments didn’t only influenced the content of sugar and acid, but also their metabolizing enzymes in Huangguogan fruit. The Best potash, phosphate were respectively3:1:4:2,2:3:4:1by studyding with potassium, phosphorus nutritional impact of Huangguogan.The effect of Potassium fertilizer on the accumulation soluble sugar content and organic acid degradation of fruits mainly in the early and mid periods, that the key to increase sugar drop acid potassium phosphorus fertilization periods.(5)Different potassium and phosphorus application treatments were also affected the content and tend of available potassium,phosphate in the soil and total potassium,phosphorus content in the leaves of different periods. Actual production and experimental study conclusions. The best potassium phosphate ratio of bud fertilizer, blossom drop fertilizers and swelling fruit fertilizer were3:1:4:2and2:3:4:1. Considered from the perspective of potassium and phosphorus nutrition the content of anthesis rapidly available potassium and available phosphorus were32.24mg/kg and36.46mg/kg in the soil;4.10g/kg and2.55g/kg in the leaf. the content of young fruit period rapidly available potassium and available phosphorus were91.58mg/kg and132.36mg/kg in the soil;5.10g/kg and3.27g/kg in the leaf, the content of fruit enlargement initial period rapidly available potassium and available phosphorus were68.69mg/kg and90.25mg/kg in the soil;5.38g/kg and3.58g/kg in the leaf, the content of veraison rapidly available potassium and available phosphorus were96.65mg/kg and86.47mg/kg in the soil;5.81g/kg and2.76g/kg in the leaf. When applied to actual production, can refer to the proportion of the preferred potassium phosphate to meet the needs of the various periods of potassium, phosphorus.