Leaf Nutrient Status, Tree Growth, Productivity and Fruit Quality of Feutrell's Early Mandarin In Relation to Pre-Harvest Application of Boron and Zinc

Foliar application of boron (B) and zinc (Zn) as boric acid and zinc sulphate respectively, either alone or in combination (control, 0.3% boric acid at fruit set stage, 0.5% zinc sulphate at fruit set stage, 0.3% boric acid + 0.5% zinc sulphate at fruit set stage, 0.5% zinc sulphate + 0.3 % boric acid at premature stage) were applied to Citrus reticulata Blanco cv. Feutrell’s Early to investigate their influence on the leaf nutrient status, vegetative growth, productivity and fruit quality. The leaf K, Mn, Fe, B and Zn status of ‘Feutrell’s Early’ mandarin trees significantly increased with foliar applications of boric acid and zinc sulphate. The levels of Zn and B in the of ‘Feutrell’s Early’ mandarin leaves increased from deficient to optimum range, with higher leaf size, fruit weight, juice weight percentage, SSC and TA with application of 0.3% boric acid and 0.5% zinc sulphate at the fruit set stage as compared to all other treatments.  The concentration of ascorbic acid significantly increased in ‘Feutrell’s Early’ mandarin fruit harvested from trees treated with 0.3% boric acid and 0.5% zinc sulphate at pre-mature stage. The trees sprayed with 0.5% zinc sulphate at fruit set stage exhibited higher amount of non-reducing and total sugars in their fruit juice as compared to all other treatment. In conclusion, the ‘Feutrell’s Early’ mandarin tress sprayed with combine application of 0.3% boric acid and 0.5% zinc sulphate at fruit set stage effectively improved the leaf B and Zn level, tree growth, yield and fruit quality.

Submitted for oral presentation