Study On Relationship Between Nutrition Status And Fruit Quality Of Introduced Citrus Paradisi Macf.

Mineral nutrients were key factors in raising yield and improving quality. In this paper, in order to offer scientific basis for rational fertilization, and improve high quality-yield, the available nutrient in soil of the grapefruit (Citrus paradisi Macf.) orchard, the mineral elements in leaves and in fruits, the correlation of mineral elements between leaves and fruits of nine grapefruit varieties were investigated. Their effects on sugars, acids, vitamin C and total dissolved solids contents were also studied. The main results were as follows:1 Research was made on some indexes of soil in the grapefruit orchard. The soil indexes include alkaline nitrogen, available phosphorus, manganese, zinc, iron and exchangeable potassium, calcium, magnesium. The status of mineral elements of soil in grapefruit orchard was studied. The result showed that alkaline nitrogen, magnesium, available manganese were in optimum range; exchangeable Ca, available content were deficient; available zinc content was higher than optimum range; available iron content were low. Soil condition between various plots was consistent. They had not remarkable difference.2 Research was made on mineral elements in leaves of grapefruit. The results showed that P, K, Zn content were too high; Fe content was higher than optimum range; N content was in optimum range; Ca, Mg, Mn content were low and at the varying degree of deficient condition.3 Research was made on mineral elements in fruits of grapefruit. The results showed that N, K, Ca, Mg, Zn content were all lower than optimum range and at the varying degree of deficient condition; K content was in optimum range, P content was in high range.4 Nine varieties of grapefruits quality have been analyzed. The result showed that, the fruit's quality of number 4#, 1# and 3# are excellent, and number 5# was worse than other.5 The correlations between mineral elements in soil of grapefruit orchard and in leaves of grapefruit were as follows: Zn was extremely significant positive correlation; Fe was extremely significant negative correlation; P, Mn were negative and positive correlation respectively, but each of their correlations was not significant; each correlation of N, K, Ca, Mg was in low degree.6 There were different degrees of the correlations between mineral elements and inclusion in fruits of grapefruit. The content of N, P, K, Ca, Zn in fruits were extremely significant positive correlated with sugar content of fruits. N content of fruit showed extremely significant negative correlation with acid contents of fruits. Vitamin C content of fruits showed extremely significant positive correlation with P, K, Ca, Zn in fruits. Total dissolved solids contents of fruits showed significant positive correlated with Ca and Zn in fruits. There were different degrees of the correlation between mineral elements in leaves and inclusion in fruits of grapefruit. The sugar content of fruits was significant or extremely significant negative correlation with the content of N and Mg in leaves. K content in leaves showed significant negative correlation with acid content of fruits. Vitamin C content of fruits showed significant positive correlation with Fe content in leaves. There was not significant positive correlation between mineral elements in leaves and the total dissolved solids contents of fruits.7 The synthesis quality of grapefruit was extremely significant positive correlation with N, P, K, Ca, Zn content of fruit. And it was extremely significant negative correlation with N content of leaves.