Effect Of Different Ca/Mg Ratio Fertilizers On Yield,Quality And Calcium And Magnesium Uptake Of Pomelo

Guanxi pomelo orchard in Pinghe County,Fujian Province and Shatian pomelo orchard in Meizhou City,Guangdong Province are suffered from severe soil acidification and soil available Ca²⁺and Mg²⁺deficiency.In order to solve the problem we used 15a white fruit Guanxi pomelo and 20a Shatian pomelo as test materials to carry out field plot test.The experiment was conducted from 2017 to2018,we analyzed the effects of Ca/Mg ratio fertilizers on the yield,quality and absorb efficiency of Ca²⁺and Mg²⁺.In the field trial area,it is important to define the soil acidity ameliorate of the suitable Ca/Mg ratio fertilizers,which can provide theoretical basis and technical support for the quality improvement and healthy development of the pomelo industry.The main results are as follows:?1?The application of Ca and Mg fertilizers can increase the yield of Guanxi and Shatian pomelo,with increase rate of 5.69%to 61.42%.The application of Ca/Mg ratio?9:1?to Shatian pomelo reached the highest increase rate of 61.42%in 2018 and33.67%for two years average among all treatments.There was a significant positive correlation between the yield of pomelo fruit and the amount of CaO applied,meanwhile Ca/Mg ratio.?2?The fruit weight,juice rate and yield of Guanxi pomelo increased significantly with the increase of CaO application rate.The MgO application significantly increased the moisture content of fruit valve and decreased the thickness of peel,but the soluble solid concentration of fruit also decreased significantly.As the ratio of calcium to magnesium fertilizers decreased,the thickness of peel became thinner,and the moisture content of peel and valve was significantly increased.The edible rate,fruit shape index and titratable acid of Shatian pomelo significantly increased with the increase of calcium and magnesium fertilizers application.The thickness of peel was significant negative correlation with the amount of CaO applied.The ratio of high Ca/Mg ratio significantly decreased the fruit juice rate.?3?There was a significant positive correlation between chlorophyll concentration and magnesium concentration in Shatian pomelo orchard in May,September and November 2018,but its decreased with the increase of Ca/Mg ratio.The chlorophyll concentration of Guanxi pomelo leaves is not significant related to magnesium concentration.?4?The leaves calcium concentration increased with the leaf age.The leaf Mg concentration of 2017 to 2018 was highest in May,decreased in July and September,and remained relatively stable in November,however,but still deficient widespread.There has a significant positive correlation between leaf Ca/Mg and the corresponding fertilizer application.The leaves Mg concentration decreased with the increase of Ca/Mg ratio significantly in Shatian pomelo orchard but not significantly in Guanxi pomelo orchard.The correlation between leaf Ca and Mg concentration was significantly positively in May and July under low concentration range,and becoming weaker with leaf age increasing,until showing significantly negatively from September to November.This phenomenon indicated that the relationship between the leaves Ca and Mg absorption varies with the Ca/Mg ratio and season.?5?The Ca and Mg concentrations of the peel and capsular valve were significantly higher than that in pulp.Therefore,the Ca and Mg absorption of the peel and valve dominated under application of Ca and Mg fertilizers,the concentrations of Ca and Mg in all parts of fruit?fruit,peel,valve?were significantly positively correlated with the application rate.?6?The application of Ca and Mg fertilizers had the tendency to increase the soil pH value.The application of different Ca/Mg ratio fertilizers in 2018 raised significantly the soil available Ca and Mg concentration,and the soil available Ca²⁺and Mg²⁺concentrations were increased with the application rate.There was a significant positive correlation between the ratio of Ca/Mg in the soil and the ratio of Ca and Mg fertilizers applied.However,the soil available Ca²⁺and Mg²⁺concentrations were still lack severely.?7?The application of Ca and Mg fertilizers had the tendency to increase the soil pH value.The application of different Ca/Mg ratio fertilizers in 2018 raised significantly the soil available Ca and Mg concentration,and the soil available Ca²⁺and Mg²⁺concentrations were increased with the application rate.There was a significant positive correlation between the ratio of Ca/Mg in the soil and the ratio of Ca and Mg fertilizers applied.However,the soil available Ca²⁺and Mg²⁺concentrations were still lack severely.