Relationship among Oxalic Acid and Some Mineral Contents in the Leaves of Hybrid Seedlings between Tart and Sweet Cultivar of Carambola (Averrhoa carambola L.)

Abstract

The difference in oxalic acid content between tart and sweet cultivars of carambola (Averrhoa carambola L.) was examined, specifically the difference of total oxalic acid content in leaves, and the proportion of insoluble oxalic acid of total oxalic acid content in fruits. We thought that taste acidity could be reduced by decreasing the proportion of the soluble oxalic acid content in the total oxalic acid content of carambola fruits. The relationships among oxalic acid, potassium, calcium and magnesium contents in leaves were examined in hybrid seedlings of tart and sweet cultivars of carambola. Total oxalic acid content closely correlated with insoluble oxalic acid content. The correlation coefficient between insoluble oxalic acid and calcium content was highly significant compared with potassium and magnesium. These results suggested that the total oxalic acid content in leaves was strongly influenced by the calcium content, and it appears to be decreased by the regulation of calcium content.