Effect Of Calcium Solitions Spraying On Fruit Quality And Storage Property Of 'Jinlinghuanglu' Peach

Peaches are typical climacteric fruits.During postharvest stage,peach fruits are easy to cause fruit decay and physiological diseases,which adversely reduced the fruit quality and commodity value.To maintain fruit storage quality and reveal the main factors affecting the storage resistance and transportation,this study used fresh yellow flesh peach variety'Jinlinghuanglu'as trial materials,and analyzed the peach leaf and fruit calcium absorption,fruit cell ultrastructure,and the external quality and internal qualityof 'Jinlinghuanglu'fruits,under different calcium spraying treatments.Combined with the change of related enzyme activity in the process of low temperature storage,we discussed physiological mechanisms of fruit quality and storage resistance and transportation,especially under calcium spraying treatments,the main results were as follows:1.changes of the calcium content in leaf,pericarp and flesh of 'Jinlinghuanglu'peaches during different fruit developments were measured,as well as observation of pulp cell ultrastructure in cryopreservation of 25 d.Results showed that calcium spraying increased the calcium content in leaf,pericarp and flesh.The effect was more effective in young fruit period.The highest level of calcium content was observed on 0.015 mol/L chelated calcium treatment in the various tissues.Inaddition,calcium was mainly distributed in cell wall,cell membrane and tonoplast.What's more,calcium was accumulated in tonoplast and clear cell structure was found.The most effective treatments were both 0.02 and 0.015 mol/L chelated calcium treatment.Little calcium was found in control fruit and cell wall distort,disappeared cell compartment and abnormal cell structure were observed.In addition,structure and function of cell membrane system were injured.We can concluded that calcium spraying on leaf and fruit could increase fruitcalcium content and structure and function of cell were protected.The most effective treatment was 0.015 mol/L chelated calcium.2.changes of dorganic acid content,soluble sugar content,soluble solid content and fruit firmness in 'Jinlinghuanglu' peaches during low temperature storage were measured.Results showed that suitable concentration of calcium spraying significantly increased the fruit firmness,inhibited fruit softening.Simultaneously,the soluble solid content and soluble sugar content was raised,while the organic acid content was reduced,under calcium spraying treatment.Spraying calcium treatment also increased the total sugar content,decreased the total acid content,favorably mitigated the disorder of original fruit flavor caused by its sharply fell of sugar/acid ratio,and beneficially enhanced the fruit quality.This study argues that chelating calciumspraying at the concentration of 0.015 mol/L advantage ously delayed the decrease of fruit firmness,increased the soluble sugar content,and reduced the content of organic acids,with the intent to access better quality and taste,improve the storage quality of peach fruits.3.changes of the pigment and chromatism index in 'Jinlinghuanglu'fruit during low temperature storage were measured.In this study,calcium spraying treatment significantly reduced the chlorophyll contentin peach skins,whereas no difference was observed in the chlorophyll content under rinsing water spraying treatment.From the 10th day to the end of low temperature storage phase,either carotenoid or anthocyanidin content was significantly higher than that of control,respectively,under calcium spraying at the concentration of 0.015 mol/L and 0.005 mol/L.Notably,the appearance quality of peach fruits was mostly improved especially under 0.015 mol/L chelating calcium spraying treatment.Different calcium spraying treatment significantly increased the difference of red and green(a'),but suppressed the difference of yellow and blue(b*).And the hue angle was significantly lower than that under rinsing water spraying treatment.However,there was no significant difference in fruit brightness values(L*)and saturation(C)between calcium spraying and rinsing water treatments.These findings indicated that calcium spraying treatment before harvest favorbly improved coloration of fruit skin,restrained skin color to turn yellow,and maintained the brightness of peach fruits,under low temperature storage process.4.changes of the fruit decay rate,weightlessness rate,total polyphenols,flavonoids and oxidase activity during low temperature storage were measured.Results of this study showed that spraying different concentrations of calcium significantly reduced the fruit decay rateand weightlessness rate under low temperature storage,in which treatment effect was the best at the concentration of 0.015 mol/L chelating calcium spraying.During the whole cold storage shelves,the total phenol content and flavonoids content under 0.015 mol/L chelating calcium spraying was significantly higher than that under rinsing water treatment,and the activity of PPO,PG,PME and LOX oxidase was also significantly lower than that under rinsing water treatment.In particular,calcium spraying treatment effectively restrained the activity of oxidase,delayed fruit late softening after harvest,maintained the fruit decay rate,improved the storage resistance of peach fruits.Meanwhile,correlation analysis showed that fruit decay rate was positively correlated with the LOX,PPO enzyme activity,and negatively correlated with flavonoids,total phenol.And PPO,PME enzyme activity and flavonoids was also in a significant negative correlation with total phenol.Visible oxidase activity and total phenol and flavonoids antioxidants play key roles in the softening process under low temperature storage in'Jinlinghuanglu'fruits.