Construction Of Fruit Development Dynamics,Fruit Quality And Starch Staining Atlas Of Different Apple Varieties In Aksu

Aksu region is an important apple producing area in Xinjiang,and due to the unique climatic resource conditions in the region,the apples produced are renowned nationwide.At present,the main variety planted in the region is Fuji,with a single variety structure.With the current apple market homogenization problem is more serious,resulting in less efficient apple production.In recent years,with the progress of apple breeding,some varieties of apples have been introduced into the region.By analyzing the maturity of apples introduced and cultivated locally,we can determine the appropriate harvest date for apples.This is used to guide the harvesting of apples in the Aksu region and to improve the quality and storability of apples.This paper provides a theoretical basis for the renewal of apple varieties and the transformation of apple industry in the Aksu region.The main research results of this paper are as follows.（1）Fruit weight and stalk diameter showed an overall increasing trend with fruit growth and development,changing rapidly in the early stage of fruit development and gradually stabilizing after maturity.The fruit shape index showed a decreasing trend in the early stage of fruit development,and then changed slowly and stabilized after fruit maturity.（2）Iodine-starch staining profiles of 12 apple varieties at maturity were produced and classified into seven classes according to the staining area of the flesh from large to small and the degree of staining from dark to light.With the extension of the harvesting period,the starch index of the fruit showed a gradual increase and the staining area of the starch staining map decreased step by step.（3）With the extension of harvesting period,fruit hardness,titratable acid content,and ascorbic acid content of different apple varieties showed a decreasing trend and soluble solids content showed an increasing trend.Significant or highly significant correlations were found between the starch index and fruit hardness,titratable acid content,soluble solids content,and ascorbic acid content.Therefore,iodine-starch staining profiles can objectively reflect apple ripeness.（4）Fruit growth and development process,the trends of sugar and acid components of the 12 apple varieties were basically consistent.The sugar content showed an overall increasing trend with fruit growth and development,with the highest fructose content and the lowest sorbitol content.8 test varieties had higher sucrose content than glucose content after fruit ripening,and 4 test varieties had comparable sucrose and glucose contents.After fruit ripening,the fructose content was stable at 50～66 mg·g^-1,and sucrose content was stable at 24～35 mg·g^-1.Glucose content was stable at 14～27 mg·g^-1,and sorbitol content basically remained within 10 mg·g^-1.The content of acid fraction showed an overall decreasing trend with fruit growth and development,and the highest content of malic acid and the lowest content of succinic acid.In the early stage of fruit growth,the citric acid content was significantly higher than the tartaric acid content,and the citric acid content decreased faster with fruit growth and development,while the tartaric acid content decreased slowly.At the later stage of development,the tartaric acid content was higher than the citric acid content.After fruit ripening,malic acid content was stable at 3.60～6.80 mg·g^-1,tartaric acid content was stable at 0.80～1.50 mg·g^-1,citric acid content was stable at 0.25～1.40 mg·g^-1,and succinic acid content was basically zero.