Appropriate content of leaf mineral element in high quality persimmon orchard

Abstract: 【Objective】In this study, fruit quality and leaf mineral element contents of‘Yang Feng'persimmon were measured. The samples were collected from 26 different orchards in Mei county, Shannxi province. The relationship between leaf mineral element contents(N, P, K, Ca, Mg, Fe, Mn, Cu, Zn) and fruit quality indexes(weight, shape index, firmness, soluble solids, titratable acidity, soluble tannin and vitamin C) was analyzed by using principal component analysis. To simplify the evaluation index, we constructed a scientific evaluation system for fruit quality. According to this system, persimmon samples were divided into two grades, high quality ones and common ones. Based on the mineral element contents in the leaves of high quality persimmon, we determined the appropriate values for‘Yang Feng'persimmon in Mei county.【Methods】In early October, 8 leaves and five fruits were taken from each of three plants in every chosen orchard. Totally, twenty- four leaves and fifteen fruits were sampled for each orchard andbrought to the laboratory for analysis. The weight, shape index, firmness, soluble solids, titratable acid, soluble tannin and vitamin C were measured for fruit samples as well as N, P, K, Ca, Mg, Fe, Mn, Cu and Zn contents for the leaf samples. Those indexes were transformed via membership function method, and the principal component analysis(PCA) was performed with SAS software. Taken principal component contribution rate as weight, the comprehensive score of each sample was calculated by weighted summing the first five principal component values. According to those calculated comprehensive scores of persimmon samples, the fruits were divided into samples from high-quality orchards and samples from the common ones. The appropriate mineral element contents of persimmon leaves were obtained by analyzing leaf mineral elements in high quality orchards.【Results】The PCA results showed that the cumulative contribution proportion of the first five principal components was 89.2 %, which meant the information of those 5 components accounting for 89.2% of the total, and met the demand of analysis basically. The first principal component mainly reflected fruit weight, firmness and soluble tannin; the second one mainly reflected fruit weight and vitamin C; the third one reflected brix and titratable acidity; the fourth one reflected fruit shape index and titratable acidity. The fifth one reflected soluble tannin. Fruit weight showed in the first and the second principal component, titratable acidity in the third and the fourth, and soluble tannin in the first and the fifth, which meant fruit weight was the most important index for the fruit quality evaluation system. Twelve of 26 samples were classed into high quality orchard samples, and the rest were common ones. The fruit weight, fruit shape index, brix, titratable acidity and soluble tannin of high quality samples were better than that of the common ones, while firmness and vitamin C on the contrary. The average contents of N, K, Ca, Mg and Zn in leaves of high-quality samples were higher than that of the common ones, while the average contents of P, Fe, Mn and Cu were lower. However, the variation coefficient of all mineral element content except K in high-quality sample leaves were smaller than in common ones,which might be caused by the imbalance of leaf mineral element content in the common samples. The appropriate mineral element contents of‘Yang Feng'persimmon leaf were in the range of: 1.88%-2.20%for N, 2.29-4.19 mg·g^-1 for P, 3.4-11.62 mg·g^-1 for K, 21.19-39.78 mg·g^-1 for Ca, 5.15-7.95 mg·g^-1 for Mg,210.94-361.72 mg·kg^-1 for Fe, 446.05-1177.85 mg·kg- 1for Mn, 21.67-70.07 mg·kg- 1for Zn and0.11-20.89 mg·kg^-1 for Cu.【Conclusion】Fertilizer should be guided according to the scientific results of the leaf mineral elements analysis.