Effects of water stress on water use and yield of onion

Abstract

The study of effects of water stress on yield and water use by onion plants was carried out at the experimental field of the Institute of Field and Vegetable Crops in Novi Sad in the period 2005-2007. Onion sensitivity to water stress was determined using a yield response factor (Ky). The values of Ky were derived from the linear relationship between relative evapotranspiration deficits (1-ETa/ETm) and relative yield decrease (1-Ya/Ym). To assess the irrigation effect on onion yield, irrigation water use efficiency (Iwue) and evapotranspiration water use efficiency (ETwue) were determined. Values of Ky in the growing season (Ky 1.78) indicate that onion is highly sensitive to water stress under the climate conditions of the Vojvodina region. The amounts of water used on evapotranspiration under irrigation and non-irrigation conditions ranged from 448.4 to511.9 mm, and 290.2 to 393.9 mm, respectively. The values of Iwue and ETwue varied from 4.35 to 28.05 kg ha-1/m-3 and 7.87 to 19.51 kg ha-1/m-3, respectively, mostly depending on the favorableness of the year for the onion production and irrigation water applied. Ky, Iwue and ETwue can be used as a good basis for onion growers in the region in terms of optimum irrigation water use, for the planning, design and operation of irrigation projects in the region, and also for the improvement the production technology of the crop.