The study analyses the response of onion to different irrigation levels with microsprinkler irrigation system. The four treatments comprised different ratio of irrigation water (IW) to cumulative pan evaporation (CPE) namely 0.60 (T1), 0.80 (T2), 1.0 (T3) and 1.20 (T4). Irrigation had significant effect on growth parameters of onion and subsequently influenced the crop yield. The best yields were recorded from T3 and T4, associated with the higher percentage of bulbs having diameter greater than 45 mm. Protein content in bulbs was highest when associated to T1, but the loss in marketable produce during the storage was also highest in T1. Irrigation water use efficiency and water use efficiency both were highest in T2 and then declined with the increase in irrigation. Hence, in water constraint situation, T2 would be the most appropriate irrigation level for onion production with microsprinkler irrigation system. Production functions of yield versus irrigation water applied and yield versus crop evapotranspiration were found to be polynomial. The developed functions can be used as a guide to yield potential allocation decision related to limited irrigation water.
