INTEGRATED NUTRIENT MANAGEMENT IN ONION-A REVIEWK. Gnanasundari, S. Srivignesh, K. Rama Krishna, Manish Kumar and A. Ramesh Kumar
Onion (Allium cepa L.) is a bulbous vegetable crop and cultivated in many parts of the world. Onion ismajorly used in our daily diet for its nutritional value. In onions, sulfur-containing compounds and allinaseenzymes are responsible for their lachrymatory effect and pungency. Flavanoid compounds in onions likekampeferol and quercitin show anti-inflammatory and antioxidant properties. Globally, India stands secondin onion production, book keeping for 10 % of total production from 16 % of total area. As per FAO data(2012), China leads the world in production (20.5 million tonnes), followed by India (13.3 million tonnes).Maharashtra, Madhya Pradesh, Karnataka, Rajasthan, Bihar, Gujarat, Andhra Pradesh, Haryana, WestBengal, Gujarat, and Uttar Pradesh are the top onion-producing states in the country, contributing nearly90% of the countryâs overall onion production. Maharashtra stands first in production with 8,854.09 thousandtonnes with 38.09 percent share, followed by Madhya Pradesh (15.92 percent share) and Karnataka (12.85percent share) (https://agriexchange.apeda.gov.in). Onion is a nutrient-sensitive crop and the nutrientrequirement varies with cultivar, location, and season. Fertilizer recommendation for onion crop is 100-150kg N, 40-80 kg P2O5, and 0-125 kg K2O per hectare (Source: NHB). Many studies have reported that 2.1 kg N,0.75 kg P2O5, 2.2 K2O, and 0.28 kg S per hectare of nutrients are removed by onion crop to produce a bulbyield of 1 ton (DOGR, 2015). Use of synthetic fertilizers alone causes leaching, increases toxicity, and degradesthe soil environment. A Study by Kwagheet al. (2017) have shown that nutrient uptake by the onion cropenhanced to 0.76, 43.82, and 2.42 kg/ha by the combination of both organic and inorganic fertilizers, therebyincreasing the crop yield. Therefore, a rising need exists to provide an adequate and balanced nutrientapplication for attaining good crop yield and quality without affecting soil fertility status. This INM basedapproach for nutrient management has a positive impact on plant growth, agricultural sustainability, andfertility of soil. Hence to enhance soil fertility and to improve the nutrient uptake, the concept of IntegratedNutrient Management (INM) could be adopted.