The Relation Of The Fruit Quality To Calcium, Magnesium, Boron Nutrition And Its Regulation Of Changshan Huyou, ZheJiang

Changshan is famous for its Huyou production. But the quality degradation issue of Changshan Huyou due to nutrients deficiency, inappropriate management and limited budget input has been a concern in the past several years. Nutrients supply is considered to be the key factor governing the fruit quantity and quality. Based on the survey on soil fertility and plant nutrient status in typical citrus orchards in Changshan, Zhejiang, this study investigated the temporal nutrients changes in leaves and fruits. The results revealed the significant importance of Calcium (Ca), Magnesium (Mg) and Boron (B) in regulating nutrients balance of the trees and promoting fruits yield and quality, and recommended the beneficial fertilization practices. The main conclusions are following:1. Effects of Ca, Mg and B fertilization on the nutrients status in soils, leaves and fruits. The Ca, Mg and B contents in the leaves and fruits of Huyou were inceased by applying Ca, Mg and B fertilizers. The effect of combined application of Mg and B fertilizer on enhancing fruits Mg accumulation was greater than applying Mg alone. The soil pH and available Mg contents were raised significantly by combined application of Mg and Ca. and the contents of soil available B were increased by B application significantly.2. Effects of Ca, Mg and B fertilization on the seasonal changes of Ca, Mg and B contents in Huyou leaves and fruits. In all the treatments, Ca contents of leaves exhibited consistent temporal changing pattern annually, were at the lowest at sprouting stage, then increased remarkably with the leaves growing, and reached the highest level at the mature stage. Ca contents of fruits also exhibited similar changing pattern in all treatments, with relatively lower at the early stage of fruit enlargement and the highest at the mature stage. In all treatments, the lime application resulted in the highest Ca concentration of leaves and fruits around a year.Magnesium contents of leaves and fruits tended to change consistently in all the treatments. Mg contents of leaves peaked at the early stage of fruit enlargement (July) while those of fruits was decreased with maturing and reached the lowest at the mature stage. The treatment with MgSO4 resulted in the highest Mg concentration of fruits.Boron contents of leaves and fruits also tended to change consistently in all the treatments. B concentration of leaves was the lowest at young fruit stage (May) and the highest at the late stage of fruit enlargement (September). B concentration of fruits was increased with maturing, and reached the highest at mature stage. The treatment with B application resulted in the highest B concentrations in fruits and leaves.3.Effects of Ca, Mg and B on fruit quality of Huyou. In all the treatments, the combined application of Mg and B had significantly promoted the contents of soluble sugar, the ratio of solid to acid and longitudinal diameter of fruits, but significantly decreased the content of fruit titratable acid. The Mg application had significantly increased the concentrations of fruit soluble solids and the combined application of Ca and Mg had significantly elevated the concentrations of fruit vitamin C.4.Correlation analysis revealed that contents of Mg, Ca and B of leaves and fruits in Huyou positively correlated with soil available Ca, Mg and B contents in the citrus orchards, with the correlation between leaves Mg contents and soil available Mg being significantly positive. B concentration of leaves significantly positively correlated with the soils available B, while that in fruits negatively correlated with soil available B. Ca, Mg and B contents in leaves correlated well with those in fruits, with the leaves Mg and B contents significantly correlated with fruits Mg and B concentrations, respectively.5.Calcium, Mg and B contents in leaves and fruits correlated positively with most of the quality parameters. Mg in leaves and fruits correlated best with fruit quality at fruit mature stage. They were significantly positively correlated with Vitamin C and ratio of solids to acids and negatively correlated with titratable acid content. At the early enlargement stage (July) B contents in leaves were significantly positively correlated with vitamin C in fruits, and negatively correlated with titratable acid content. At the late enlargement stage (July) B was significantly positively correlated with ratios of solids to acids and negatively correlated with titratable acid content. Soil available Ca was significantly negatively correlated with soluble sugar in fruits. Soil available Mg was significantly positively correlated with vitamin C in fruits.