Leaf carbohydrates in 'Ponkan' mandarin fruit quality under chemical thinning

Abstract

This study was performed to verify the influence of the levels of leaf carbohydrates on the fruit quality of 'Ponkan' mandarin trees subjected to chemical thinning for three years using different Ethephon concentrations. Five concentrations of Ethephon were tested: 0, 200, 400, 600 and 800 mg L-1, which were applied during the stage of fruit development when fruits were from 25 to 30 mm in transverse diameter. The experimental design was in randomized blocks, with four blocks and four plants per plot. Interactions were observed between the concentrations of Ethephon and the year of assessment for the percentage of thinning, transverse diameter, longitudinal diameter, mass, soluble solids, acidity and the ratio of fruits. For the contents of carbohydrates, there was an interaction between the concentrations of Ethephon, the years of assessment and the leaf sampling times (flowering and harvest). Maintenance of high levels of leaf carbohydrates resulted in improvement of the quality of 'Ponkan' mandarin fruits. Chemical thinning conducted with Ethephon concentration of 600 mg L-1 maintained carbohydrate levels suitable to improve the quality of 'Ponkan' mandarin fruits.