INFLUENCE OF GIRDLING ON THE SEASONAL LEAF NUTRITION STATUS AND FRUIT SIZE OF ROBINSON MANDARIN (CITRUS RETICULATA BLANCO)

Abstract

This study was undertaken to investigate the effects of single and double girdling applications on the fruit yield, commercial size, quality, photo system II (PSII), leaf chlorophyll and leaf nutrition content of 22-year-old Robinson mandarin (Citrus reticulata). Girdling treatments were performed at anthesis (when 60% of the flowers were opened) with approximately 5 mm trunk diameter in 2014. The fruit was harvested in 2014 at the optimum harvest time (in December) for fruit yield, properties and size. Evaluations of leaf mineral content, chlorophyll concentration and fluorescence measurements were performed at monthly intervals. Leaf samples were taken in eight periods for analysis of plant nutri-elements. It was determined that double girdling was the best application in terms of fruit yield and percentage of marketable fruit. The treatments did not significantly affect fruit internal quality. Girdling reduced PSII and leaf chlorophyll concentration but did not affect leaf mineral content. However, we observed a tendency toward a decrease in nitrogen levels in the girdled trees. According to the results of the present study, girdling treatments significantly affected fruit yield and size together with several macro-micro plant nutri-elements.