ONION TECHNICAL Introduction Onion is an important vegetable crop in India. It is considered by many, to be as the most politically sensitive crop, having brought down governments in the past. India has the largest area under onion in the world but is second to China in production. A number of agencies are involved in research for improving the quality, production and productivity of onions. The Nasik region of Maharashtra is the major producer of onion in the country accounting for almost 30% of the total crop. It is followed by Karnataka, Uttar Pradesh and Tamil Nadu.   Varieties Following are some of the important varieties of onions developed in India Variety Source Characters COMMON ONION Red varieties Pusa Red IARI Red bulbs, flattish-round shape, yield 25-30 tonnes/ha. Very good in storage. Wider adaptability Pusa Ratnar IARI (presently NBPGR) Deep red, round, large, fair in storage, yield 30-40 tonnes/ha Pusa Madhavi IARI Light red colour, good keeping quality, yield 30-35 tonnes/ha Punjab Selection PAU Light red, yield 20 tonnes/ha N 53 NIPHAD Deep red colour yield 15-20 tonnes/ha, suitable under rainy season N 2-4-1 NIPHAD Light red, yield 20-25 tonnes/ha, suitable for rainy season Baswant 780 MPKV Bright red, yield 20-25 tonnes/ha, suitable for rainy season Arka Niketan IIHR Light red, yield 33.5 tonnes/ha. Suitable for rainy season Arka Kalyan IIHR Dark red, yield 33.5 tonnes/ha. Suitable for rainy season Arka Bindu IIHR Bright dark red, ready in 100 days, yield 25 tonnes/ha, suitable for export particularly to Malaysia and Singapore Agrifound Light Red NHRDF Light red, yield 30 tonnes/ha, good in storage Agrifound Dark Red NHRDF Dark red, yield 20-25 tonnes/ha, suitable for growing under rainy season Udaipur 101 Udaipur University Dark red, yield 20-30 tonnes/ha Udaipur 103 Udaipur University Dark red, yield 25-30 tonnes/ha Punjab Red Round PAU Red, coloured, yield 30 tonnes/ha Hissar II HAU Light red, yield 20 tonnes/ha Kalianpur Red Round CSAUAT Light red, yield 20 tonnes/ha Agrifound Rose NHRDF Dark red, yield 19-20 tonnes/ha White varieties Pusa White Flat IARI Flattish round, TSS 11-2%, drying ratio 9:1 yield 32.5-35 tonnes/ha, suitable for dehydration purpose, very good for green purposes and good in storage Pusa White Round IARI Roundish flat TSS, 12-13%, drying ration 8:1, yield 300-325 tonnes/ha, very good in storage, suitable for dehydration purposes Punjab 48 (S 48) PAU Flattish round, yield 30 tonnes/ha suitable for dehydration Udaipur 102 Udaipur University Roundish flat, TSS 12%, yield 30-35 tonnes/ha, suitable for dehydration Roundish flat, yield 25-30 tonnes/ha, good in storage, suitable for dehydration Yellow varieties Early Grano IARI Large globular bulbs, good for salad purpose, poor in storage, yield 50-60 tonnes/ha, good for green onion Brown Spanish RS, IARI, Katrain Long-day type, can only grow in hills, maturity 160-180 days, yield 28 tonnes/ha, stored up to 6 months Multiplier onion CO 1 TNAU Light red, medium sized, lateral bulbs 7-9, maturity 65 days, yield 12 tonnes/ha CO 2 TNAU Light red, lateral bulbs 7-9, clump weight 60-65 g, maturity 65 days, yield 120 tonnes/ha resistance to thrips and purple blotch CO 3 TNAU Pink, lateral bulbs 8-10, clump weight 75 g, bigger-sized bulbs, yield 16 tonne/ha, maturity 65 days, liked by consumers, medium resistant to thrips CO 4 TNAU Lateral bulbs 8-10, weight clump 90 g, maturity 60-65 days, medium tolerant to thrips MDU 1 TNAU, Madurai Lateral bulbs 10-11, clump weight 75 g, yield 15 tonnes/ha, maturity 60-65 days, good keeping quality, resistant to lodging Agrifound Red NHRDF, Dindigal Clump weight 65-68g, light red, yield 18-10 tonnes/ha As onion is a crop of national importance a number of agencies are involved in conducting research to increase its quality, production and productivity.   Disease And Pest Management The onion crop is susceptible to a number of diseases. Some of the main diseases and their recommended remedies are given below: Name of Disease / Pest Recommended Remedy Purple blotch (Alternaria porri) Spray Dithane M-45 (0.25%) with sticker triton; first spray on appearance of disease, followed by spray at 15-day interval to get best results. Stemphylium blight (Stemphylium vesicarium) 5 preventive sprays at 15-day interval in bulb crop of Mancozeb (0.25%). Mancozeb (0.25%) or copper oxychloride at 15-day interval for seed crop. Onion thrips (Thrips tabaci) 4 sprays at 15-day intervals of Malathion 0.1%, or 0.075% Metasystox with sticker. In seed crop at flowering it is advisable to use Indosulfan 0.1% or 0.2% spray. Apply Phroate or Carbofuran granules @ 1 kg ai/ha 30 days after transplanting, followed by 2 sprays with 0.01% Cypermethrin 60-80 days after transplanting. According to the Department of Agricultural Research and Education, ICAR, Government of India, rear blight on onion is effectively managed by 4 sprays of Mancozeb (0.3%) + Cypermethrin (0.01%) at 15 days intervals starting from 25 days after planting with a cost: benefit ratio of 1:15.45 at Junagadh and Rahuri. Three sprays of Mancozeb (0.25%) and mixed with 0.015% Cypermethrin starting with appearance of disease and subsequent sprays at 15 days intervals were effective to control leaf blight disease of onion at Sabour. The treatment reduced 10.3% disease incidence and increased yield (27.1 tonnes/ha) with a cost: benefit ratio of 1:9.6.