EFFECT OF N, P, K, Zn AND B NUTRIENTS ON GROWTH, YIELD AND QUALITY OF ONION (ALLIUM CEPA L.) AND FERTILITY STATUS OF SOIL IN ALFISOLS OF SOUTHERN TAMIL NADU, INDIA

Killikulam, Tamil Nadu, India during rabi season of 2019-20 and 2020-21 to study the effect of soil test crop response (STCR) application of macronutrients in addition to boron and zinc on the growth performance, yield attributes, quality of onion and soil fertility.Experiment was laid out in randomized block design (RBD) replicated thrice using onion variety CO (On) 5 as a test crop.The performances were significantly influenced by the application macro nutrients with micro nutrients viz., zinc and boron based on STCR.Application of STCR as 106:97:54 kg of NPK ha -1 + ZnSO4 @ 25 kg ha -1 + 0.5% foliar spray significantly influenced the growth with tallest plant (55.2 cm), maximum number of leaves (17.2), and yield attributes of maximum polar diameter (3.35 cm), bulb lets (6.4/clump), bulb weight (85.2 g/plant) and bulb yield (16.85 t ha -1 ).The quality parameters and soil fertility status were also improved for the same treatment.The lowest growth, yield characters, bulb yield and quality with lower fertility status were observed in absolute control.TheSTCR recommendation as 106:97:54 kg of NPK ha -1 + ZnSO4 @ 25 kg ha -1 with 0.5% foliar spray was found to be the best for onion production and sustaining soil health in the semi-arid tract of southern Tamil Nadu, India.