[Objective] The aims were to explore the relationship between the contents of fruit mineral elements and quality features of the ＇Fuji＇ apple, screen major mineral elements of the fruit affecting fruit quality features, and set up optimum proposals of fruit mineral elements for good fruit qualities, so as to provide a theoretical basis for the reasonable orchard soil and foliar fertilizer applications to increase fruit quality and reduce the physiological diseases related to the ＇Fuji＇ apple. [Methods] The fruit mineral elements and quality indicators of ＇Fuji＂ apples were in- vestigated and analyzed, which were collected from the 153 commercial apple or- chards of ＂Fuji＇ apple located in 51 counties. The variable importance for projection （VlP） of partial least squares regression （PLS） method was used to analyze the model effect and weight analysis impact of the fruit mineral element contents to fruit quality, screen out major factors of fruit mineral elements influencing the different fruit qualities, and set up the regression equation of the fruit qualities and major fruit mineral elements. Linear programming was used to obtain optimum proposals of the fruit mineral elements to achieve good ＇Fuji＇ apple qualities. [Results] The mineral elements content and quality characteristics in ＂Fuji＇ apple fruit had great differences in the different produce regions in which the maximum content of nitro- gen, iron, zinc and boron in the ＇Fuji＇ fruit were12.06, 6.17, 7.7, and 10.08 times greater than the minimum respectively, and the differences for titratable acid and the SSC/TA ratio were 2.33 and 2.16 times respectively. The correlation analysis between the fruit mineral element contents and qualities showed that the nitrogen content of fruit had a significantly negative correlation with the soluble solid content, SSC/TA ratio and red color area, while the calcium and iron contents in the fruit were in significantly positive correlation with the soluble solid content and SSC/TA ratio
[Objective] The objective of the study was to elucidate the duplicate collinearity diagnosis method for soil nutrient and provide basis for establishment of multiple regression model of relationship between independent variable and depen- dent variable in fruit trees. [Method] An investigation on soil nutrients and ＇Fuji＇ fruit quality was conducted at 153 commercial apple orchards in the production re- gions of 51 counties in China from 2011 to 2012. At first, the regression equation was used to do the duplicate collinearity diagnosis, and then the partial least squares regression was used to analyze the weights of different soil nutrients that affected the fruit quality and screen out main soil nutrients. [Result] The results showed the conditional number between soil nutrients was 61.31, and the correlation coefficient of soil pH and available calcium, iron was 0.82 and -0.824 respectively, which demonstrated that there was multicollinearity between various soil nutrient contents. The soil organic matter, total nitrogen, available potassium, available nitro- gen, available phosphorus, available zinc, available iron and available boron showed positive effect Ioadings on fruit quality, while the }oadings and weights of the effects of available calcium and pH on fruit quality were negative. The variable importance for projection method was adopted to get the orders of the effects of major soil nu- trients on fruit quality, which was in the order of soil available calcium, nitrogen, available iron, available phosphorous, organic matter and available boron. The solu- ble solid content of the fruit was affected by soil organic matter, available phospho- rus, available iron, available boron and soil pH. [Conclusion] This study provided an analysis method and theoretical basis for the study and analysis on the relationships between dependent variables and multi-objective optimization, as well as the effects of soil nutrients on fruit quality in fruit tree.
