Effects Of Calcium Treatment On Soft Nose And Storability Of Pre-bagging ’Keitt’ Mango Fruit During Storage

’Keitt’ mango is a rosin-type mango with a large shape and is susceptible to suffer calcium-deficient physiological diseases like soft nose.As a result,the fruit will loss their quality and commercial values.In this paper,the pre-bagging ’Keitt’ mangoes were used as experimental material.The fruits were randomly divided into three groups,immersed in 1%CaCl2,2%CaCl2 or water(as control)for 2 h,and then stored at 25 ± 1 ℃.The mineral elements content,storage quality and antioxidant activity of pre-bagging ’Keitt’ mango fruit were investigated to explore the possible mechanism of calcium treatment on alleviating the soft nose,and on fruit disease resistance was also measured.The main research results were as following:(1)The fruits suffered soft nose had higher contents of N,P and K,as well as lower Ca content than that of normal mango fruits,and the mineral elements content in the disease fruit were unbalanced.Calcium treatment reduced the incidence of soft nose,increased the content of Ca in the fruit,and affected the content of other elements,which was contributed to the balance of endogenous nutrients of the fruit.(2)Calcium treatment inhibited the decreasing rate of fruit firmness index and TA content,reduced the increasing rate of fruit weight loss and SSC.The results showed calcium treatment delayed the fruit ripening process and maintained the quality of mango fruit during storage.(3)Calcium treatment effectively increased the activities of superoxide dismutase(SOD),catalase(CAT),ascorbate peroxidase(APX)and carotenoid content in the later storage stage,as well as controlled hydrogen peroxide(H2O2)at a low level,reduced the content of malondialdehyde(MDA)at the beginning period of storage.These results indicated that the calcium treatment could increase the total antioxidant ability and decrease the damage of free radical in mango fruit.(4)After immersed in calcium chloride solution,the activity of defense enzymes including chitinase(CHT),β-1,3-glucanase(GLU)were enhanced apparently,and elevated activty of phenylalanine ammonia-lyase(PAL),4-coumaroyl CoA ligase(4CL)by calcium treatment were also manifested in the late storage stage.Contents of defense substances such as total phenols,flavonoids and lignin were significantly higher than that of the control during storage.The results showed that calcium treatment improved fruit disease resistance by enhancing activities of defense enzymes,accumulating pathogenesis related proteins and defense substances.