Harvested onion bulbs under goes several physio-chemical changes like increase in respiration, physiological loss in weight (PLW), rotting and sprouting. Chemical changes in stored of onions include dry matter content, pungency, abscisic acid and fructans concentration. The seasonal differences were observed in the weight of the onions, dry matter content, glucose and total carbohydrates. Even some of the pre-harvest cultural practices like nutrition, maturity, growth regulator spraying etc and also post harvest curing would extend shelf life of onion bulbs. Onion storage in ventilation condition is satisfactory when the temperature is maintained between 25 o C to 30 o C with a relative humidity 65 to 70 per cent.
Onion (Allium cepa L.) is regarded as queen of kitchen (Selvaraj, 1976), belongs to family alliaceae (2n = 16). It is the oldest known vegetable and most important commercial crop grown in India.It is a short duration and quick growing having various uses such as vegetable, spice and medicinal purpose. India ranks 2 nd next only to china with a production of 139.00 lakh tonnes from an area of 8.47 lakh hectares and contributes15.3 per cent of the world onion production. India exports onion mainly to other countries like Malaysia, Russia, Kuwait, Sri Lanka, Singapore, Germany, Japan, Iran, Myanmar and United Kingdom. The major onion growing states are Karnataka, Maharashtra and Gujarat which contribute nearly 60 per cent of total production in country. The onion productivity in India is 16.41 t/ha which is very less than the world productivity of 20.08 t/ha. In India maximum productivity is in Gujarat 24.40 t/ha followed by Bihar (Anonymous, 2011a).In India, onion can be grown in all three seasons as kharif, late kharif and Rabi. The major season is Rabi, the onions will be available from April to May, which contributes nearly 60 per cent of total production. While, the Kharif season crop becomes available from month of October to December with production contribution of 20 per cent and late kharif (January to March) production contributing 20 per cent. The rabi season produce need to be stored for further five to six months for to avoid marketing glut and get good economics from the onion crop (Anonymous, 2011b). Lawande et al. (2009) reported some important varieties of onion cultivated in kharif season are Baswant-780, N-53, Agrifound Dark Red, Arka Kalyan and Bhima Super; in late kharif, Baswant-780, Phule Samarth, Bhima Red and Agrifound Light Red and in rabi season, varieties N-2-4-1, Arka Niketan, Agrifound Light Red, Pusa Red, Pusa Madhavi, Bhima Raj, Bhima Red can be cultivated. Although cold storage systems are used in certain countries for onion storage, this is normally not adopted in India due to poor economics and lack of cold chain facilities required to maintain the quality (Barakade, 2011). Onion storage in ventilation condition is quite satisfactory when the temperature is maintained between 25 o C to 30 o C with a relative humidity range of 65 to 70 per cent. This environment reduces t...