Effects Of Exogenous Calcium On Physiological Characteristics Of Fuji Apple

Based on the widespread calcium deficiency,frequent flowering cold injury physiological diseases and poor quality for apple orchards on Loess plateau in Southern Shanxi,20 years old "Fuji" apples were taken to study the effects of sprayed different calcium fertilizer and different concentrations during different apple growth stages to determine rational type and concentration of calcium fertilizer for improving the orchard soil environment,enhancing the fruit tree potential,increasing photosynthetic efficiency,fruit yield and quality,and promoting apple industry green development onf the Loess plateau region.The main findings were summarized as follows:1.Low temperature stress can cause the imbalance of reactive oxygen metabolism in the flower organs of apple in the flowering stage of apple,resulting in MDA content increase,and the decrease of SOD,POD and CAT activities.Spraying different exogenous calcium on flower organs significantly reduced the production of MDA and increase the activities of SOD,POD and CAT in flower organs under low temperature stress.The treatments with different concentrations of CaC12 were obviously better than the treatment with the same concentration of CaCO3 and Ca(NO3)2.The membership function value analysis showed that the strong and weak relationship was as follows:T2>T8>T3>T1>T5>T7>T6>T9>T4.In conclusion,the flower organs of apple treated with 21 mmol·L-1 CaCl2 had the strongest cold resistance,followed by 21 mmol·L-1 CaCO3 and 28 mmo1·L-1 CaCl2.2.Apple period in apple leaf spraying different exogenous calcium can increase SPAD values,net photosynthetic efficiency,transpiration rate,stomatal conductance,maximum intensity of fluorescence parameters and photosynthetic active radiation,reducing initial fluorescence intensity parameters,including the content of chlorophyll and net photosynthetic efficiency of exogenous calcium treatment were significantly higher than that of CK treatment.Through the membership function value analysis of the photosynthetic physiological indexes of 8 leaves,the improvement effect of different exogenous calcium treatment on the photosynthetic physiological performance of leaves was obtained:T8>T9>T5>T2>T7>T3>T1>T4>T6.Therefore,it can be concluded that in the period of fruit expansion,multiple CaC03 spraying can significantly improve the photosynthetic performance of leaves,and the optimal concentration is 21 mmol-L-1 CaCO3.3.Spraying different exogenic calcium on apple leaves and fruits at the early stage of apple ripening can improve the fruit shape index and fruit hardness,increase the contents of vitamin C,soluble solids and titratable acids,and reduce the ratio of solid to acid.Among them,the titratable acid content and solid acid ratio of fruits treated with exogenous calcium were significantly different from those treated with CK.Through the membership function value analysis of 6 fresh food quality indexes of apple fruits,the strong or weak relationship between different exogenous calcium treatments on the improvement effect of fresh food quality of fruits was obtained:T2>T7>T5>T1>T9>T3>T8>T6>T4.Therefore,it can be concluded that in the early stage of fruit ripening,more CaCl2 should be sprayed,which can significantly improve the quality of fresh fruit,and the optimal concentration is 21 mmol-L-1 CaCl2.