Effect of ecological factors on the quality of Ziziphus jujuba Mill. cv.“Dongzao” fruit

Relationships between main climatic factors, soil fertility and quality indexes of Ziziphus jujuba Mill. cv.“Dongzao” fruit in Boxing of Binzhou City and Xintai of Tai'an City were analyzed at different stages of fruit maturity. The results indicate that soil factors have stronger effect on soluble sugar and protein content of Z. jujube cv. “Dongzao” than climatic factors. Application of K and organic fertilizer remarkably enhances soluble sugar and protein content of Z. jujube cv. “Dongzao”. High rainfall, and P and N fertilizer application remarkably enhance titratable acid and free amino acid content, which is contrast to the effect of K fertilizer application. Vitamin C content is controlled by both climatic and soil factors. Available Cu is significantly correlated with vitamin C content. Fruit water content has positive correlation with soil texture and fertility. Excessive rainfall, and high Fe, P and Zn content in soil increase fruit shape index that make fruits long-globoid, which are otherwise ovoid in shape. Furthermore, application of Ca and Mg microelement fertilizer increases the contents of soluble sugar, Vc and soluble protein