This research was conducted to reduce the postharvest loss of Big Onion through improved curing and storage technologies and increase the economic states of onion farmer through offseason sales as well as facilitate seed production. Sri Lankan onion industry is endangered due to high postharvest losses especially due to bad weather condition at harvesting season. Field curing is constrained due to heavy rain that increases the rotting percentage. High relative humidity at the storage period also increases postharvest losses. Therefore, under this research, an onion curing and storage facility was established that is capable of controlling of Relative Humidity (RH) and Temperature. Equipment was tested for the controlling ability of Temperature and RH. Dambulla Red big onion selection was selected for the study and samples were collected directly from a farmer at Galnewa area. Those onions were subjected to heavy rain conditions at the harvesting. Two different treatments were used for the study; Shade curing and ambient storage, Artificial curing (To and RH controlled) and ambient storage. Total Postharvest Loss was low in artificial cured (38.57 % ± 2.08) onions compared to shade cured onion (62.4 % ± 3.70). This is due to reduction of rotting percentage in artificial cured onions. Rotting percentage of artificial cured onions and shade curd onions were 26.04±2.13% and 49.23±3.77% respectively after three months of storage period. It is nearly 23% reduction of rotting percentage. Therefore, artificial curing can be considered as an alternative curing practice under unfavorable weather conditions.

Another trial was conducted to test controlled atmospheric storage of big onion in the next onion season. Dambulla Red big onion variety was used for this trial as well. Two treatments were tested; ambient storage (AS) (partially rainy day: 30.05±1.48 °C, 79.31±3.76%RH; Sunny day: 33.99±1.86°C, 57.06±8.88%RH) and controlled storage (CS) (27.15±0.41°C, 70.57±7.3% RH). Total Postharvest Loss was low in onions stored at control atmospheric conditions (19.45±0.92%) compared to ambient stored onions (24.85±1.04) after one and half months of storage. Future researches are planned to test controlled atmospheric conditions for a long storage period.