Effects Of Exogenous Calcium On Calcium Metabolism And Fruit Quality Of ’Hanfu’ Apple

‘Hanfu’ apple is the largest cultivar cultivated in Liaoning Province and the largest self-breeding cultivar in China.Because of the high yield and large fruit of ?‘Hanfu’apple,physiological diseases such as bitter pox disease,water core disease and fruit cracking caused by calcium imbalance often occur in the production,which seriously reduces the commercial value of the fruit and causes great economic losses.Therefore,it is of great significance to study the effects of calcium treatment before and postharvest on calcium metabolism and quality of fruits.In this study,10-year-old ?‘Hanfu’ apple was used as test material,the effects of exogenous calcium on calcium metabolism and fruit quality of ?‘Hanfu’ apple were systematically studied through pre-harvest and post-harvest calcium treatment,in order to provide a theoretical basis for the scientific application of calcium fertilizer.The main results are as follows:1.Different calcium treatments pre-harvest effectively increased fruit weight,vertical and horizontal diameter,increased fruit firmness,soluble solids,VC content,and decreased titratable acid content.Among them,calcium sorbitol treatment was the best in improving fruit weight and hardness,and calcium amino acid treatment was the best in improving the soluble solids,VC content,titratable acid content and flavor quality.2.During the growth and development of Hanfu apple,the content of original pectin and cellulose in fruit showed a downward trend,while the content of soluble pectin increased first and then decreased.The activities of PG and CX increased gradually during development,while the activities of PME did not change much during the whole development period.Pre-harvest calcium treatment effectively inhibited the degradation of protopectin and cellulose,as well as the increase of soluble pectin content.It also significantly inhibited the activities of PG and PME.Among them,calcium sorbitol was the most effective,followed by calcium amino acid.During the development,the content of total calcium and water-soluble calcium decreased gradually,pectin calcium decreased first and then increased,calcium oxalate content increased gradually,and calcium phosphate changed little during the whole growth period.Pre-harvest calcium treatment increased the total calcium and pectin calcium content in fruits,and decreased the calcium oxalate content in fruits at later stage of development.Calcium treatment had no significant effect on water-soluble calcium and calcium phosphate in fruits.3.During storage,fruit firmness,titratable acid and soluble solids content all decreased.Calcium treatment postharvest effectively inhibited fruit firmness and titrated acid,and decrease of soluble solids could improve fruit quality and prolong fruit storage.Among all calcium treatments,calcium amino acid and calcium sorbitol treatments were more effective.4.During storage,soluble pectin increased gradually,protopectin and cellulose decreased gradually,and cell wall degrading enzymes(PME,PG,CX)activities increased gradually.Different calcium treatments significantly inhibited the increase of soluble pectin and enzyme activity,and the decrease of original pectin and cellulose content post-harvest.Among them,calcium sorbitol was the most effective treatment.During storage,the contents of water-soluble calcium and pectin calcium decreased gradually,while the content of calcium oxalate increased gradually,while the content of calcium phosphate did not change significantly.Calcium treatment after harvest could effectively increase the contents of water-soluble calcium,pectin calcium and calcium oxalate in fruits,but had no significant effect on calcium phosphate.