EXOGENOUS APPLICATION OF MACRO-AND MICRO-NUTRIENTS IMPROVES PLANT GROWTH, PRODUCTIVITY AND QUALITY OF ‘PINEAPPLE’ SWEET ORANGE

‘Pineapple’ sweet orange is an important citrus species being grown at commercial scale in Pakistan. Due to inadequate supply of macro along with micronutrients, its productivity and quality is not up to the required standard as compare to other citrus producing countries. Therefore, current study was designed in order to investigate the effect soil application of NPK (2500 g per plant in two splits) compound fertilizer (17:17:17) (T2) or foliar application of boric acid (0.3%) + zinc sulphate (0.6%) (T3) alone or in combination (T4) on growth, productivity and fruit quality of ‘Pineapple’ sweet orange. Untreated trees were kept as control (T1). Analysis of leaf mineral contents revealed that nitrogen (N), phosphorous (P), potassium (K), boron (B), and zinc (Zn) were found to increase significantly after macro and micronutrients application. Tree vegetative growth [Increase in tree height (54 cm) and tree spread (56 cm), stem girth (3.5 cm), length of flush (13.35 cm), leaf number flush^-1 (12)], fruit yield [fruit weight (23.35 kg), fruit numbers (110.75), marketable fruit % (89.72%) per tree], fruit quality [ fruit length (69.33 mm), breadth of fruit (70.06 mm), fruit weigth (211 kg), juice TSS (8.62%), TSS/Acid ratio (15.87), ascorbic acid content (31.62 mg 100g^-1), total phenolics (423.90 mg 100g^-1 FW), antioxidants (92.65%) and carotenoids (1.20 µg 100g^-1) were significantly improved by T4 treatment. In conclusion, combine application of 2500 g NPK + boric acid (0.3%) + zinc sulphate (0.6%) significantly enhanced tree growth, production and quality of ‘Pineapple’ sweet orange fruit.