Effects of soil nutrition on fruit quality of Golden Delicious strain

Abstract: 【Objective】Soil not only affects the root growth and photosynthesis of fruit trees, but also affects fruit quality, especially the organic matter and mineral nutrients in the soil. However, there are few reports on the effect of the soil nutritions on the quality of Ningxia Golden Delicious apple. In this paper, the effects of soil conditions in different producing areas of Ningxia on the quality of Golden Delicious strain apple varieties were explored to provide theoretical support for improving the quality of Golden Delicious strain apple varieties in Ningxia.【Methods】The eleven Golden Delicious strain apple varieties samples, harvested from nine orchards in Wuzhong city and Zhongwei city of Ningxia, were employed as the experiment material to analyze the fruit quality, including vitamin C content, soluble solids and acid content, solid acid ratio and hardness, fruit surface color difference and single fruitweight, fruit shape index and fruit texture, such as fruit springiness and cohesiveness, adhesiveness and breaking force, gumminess and chewiness. The fruit quality among different samples and varieties in the same orchards or different orchards was also comprehensively evaluated. At the same time, soil samples collected from the nine orchards by the soil‘S’type random multi-point sampling method were analyzed to compare the soil nutrition content difference among the different samples, such as organic matter and pH, nitrogen and phosphorus, calcium and potassium and so on. The relationship between the fruit quality and soil nutrition were comprehensively evaluated by principal component analysis and subordinate function.【Results】The results of soil analysis showed that the soil pH values of the sampling orchards were 7.81 to 8.61, and the soil was weakly alkaline. The contents of organic matter, total nitrogen, hydrolyzable nitrogen, available phosphorus, exchangeable calcium, available iron and available zinc in Wuzhong forest farm were the highest. The solid acid ratio of Zhongwei Shapotou Golden Delicious and Hongsipu Rustless Gold Spur was higher; the single fruit weight of Ningxia Wanqi Rustless Gold Spur, Qukou Farm Golden Delicious, Shapotou Fruit Golden Delicious was the highest; The fruit shape index of Ningxia Wanqi Rustless Golden Spur, Wuzhong Forest Farm Golden Delicious, Wuzhong Forest Farm Rustless Golden Delicious was larger; the fruit peel color of Futeng fruit industry Rustless Golden Delicious, Ningxia Wanqi Rustless Golden Spur was more bright. Through principal component analysis between different samples, four principal components were extracted from 15 quality indicators. Among them, the vitamin C content, soluble solids, acid content, hardness, and breaking force had higher loads on component 1, indicating that component 1 could represent these indicators. From the variance percentage contribution rate, it could be concluded that the contribution rate of component 1 was the highest, indicating that the vitamin C content, soluble solids, acid content, hardness, and breaking force could better represent fruit quality. Through the TOPISIS comprehensive analysis method in the membership function analysis method, it could be concluded that Wanqi Fruit Industry Rustless Golden Spur, Qukou Farm Golden Delicious, Shapotou Fruit Industry Golden Delicious, Futeng Fruit Industry Rustless Golden Delicious M9/Malus robusta scored higher, among them Wanqi Fruit Industry Rustless Golden Spur scored the highest, indicating that the fruit quality of Wanqi in Ningxia was the highest. The correlation analysis between the soil factors and fruit quality showed that the indexes of pH, organic matter, hydrolyzable nitrogen, total nitrogen, available phosphorus, available potassium and exchangeable calcium in 20-40 cm soil were positively correlated with the appearance quality, internal quality and texture quality of some fruits, and the correlations between the soil organic matter, hydrolyzable nitrogen, available phosphorus, available potassium and exchangeable calcium and vitamin C content, single fruit weight, vertical and horizontal meridians and texture indexes in fruit quality were significant (p＜0.05), indicating that 20-40 cm soil nutrient elements had the greatest influence on the fruit quality of Golden Delicious. It also showed that 20-40 cm soil was the main part of the soil nutritions absorbed by the roots of the fruit tree, and the soil conditions of Wanqi fruit industry were more conducive to the growth and development of Golden Delicious apple.【Conclusion】 The principal component analysis showed that the fruit quality of Wanqi in Ningxia was relatively high. Nanshantaizi was the high- quality producing area of Golden Delicious apple. The nutrient elements in 20-40 cm soil had the greatest influence on the fruit quality of Golden Delicious apple. The soil at this depth was the main part of the root system of Golden Delicious apple to absorb soil nutrients. The comparative analysis of soil conditions for the growth of Golden Delicious apples in Ningxia showed that the appearance, taste and nutrient accumulation of Golden Delicious apples were the most effective under the conditions of alkaline pH, organic matter content of 1-6 g · kg^{- 1} , total nitrogen con-tent of 0.15-0.30 mg · kg^{- 1} , hydrolyzable nitrogen content of 9.2-32.8 mg · kg^{- 1} , available phosphorus content below 10 mg·kg^-1 and available potassium content of 40-170 mg·kg^-1 .