Changes of Major Mineral Element Contents and Its Relationship with Fruit Quality in Zizyphus jujuba ‘Dongzao’ Orchard

PurposeTo study the relationship between major mineral element contents and fruit quality in Zizyphus jujuba ‘Dongzao’ orchard.

MethodsMajor mineral element contents in leaf and soil at different fruit development stages of Z. jujuba ‘Dongzao’ were assayed, and the correlation of major mineral element contents in leaf and soil with fruit quality was analyzed by canonical regression analysis.

ResultsThe contents of nitrogen (N) and phosphorus (P) in leaves of Z. jujuba ‘Dongzao’ declined generally, and obtained the biggest drop at full-bloom stage and after-flowering stage, respectively. The content of potassium (K) in leaves reached the peak value at after-flowering stage, but decreased greatly at fruit hardcore stage and white-maturing stage. With the development of fruits, soil N, P and K contents initially increased and then decreased, with the biggest drop of available N found in after-flowering stage, available P and rapidly available K appeared in fruit hardcore stage, which were 28.67%, 17.38%, and 19.56%, respectively. The contents of N and P in vegetative and fruit branch leaves showed significantly or extremely significantly positive correlations with total P in soil. The available P and total N in soil had significantly positive correlation with N in fruit branch leaves. Fruit titratable acidity contents was significantly or extremely significantly positively correlated with N in the two types of leaves. The contents of K in the two types of leaves had significantly negative correlation with fruit hardness, and was significantly positive related to fruit soluble sugar and sugar-acid ratio. The contents of N and P in fruit branch leaves were significantly positively correlated with weight of per fruit and titratable acidity, respectively. Besides, fruit soluble solid and vitamin C contents had significantly positive correlation with the content of K in fruit branch leaves.

ConclusionChanges of P content in soil exert great influence on the contents of N and P in leaf. The contents of N and K in fruit branch leaves have great influence on fruit quality. It is suggested that N and P fertilizer should be applied appropriately before full-bloom stages, and K fertilizer applied before fruit hardcore stage to improve the fruit quality of Z. jujuba ‘Dongzao’ during the practical production process.