EFFECTS OF WATER STRESS ON WATER USE AND YIELD OF MAIZE

The study of effects of water stress on yield and water use by maize plants was carried out in the experimental field of the Maize Research Institute at Zemun Polje in the period 2006-2008. Maize 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 maize yield, irrigation water use efficiency (Iwue) and evapotranspiration water use efficiency (ETwue) were determined. Values of Ky in the growing season (Ky 0.94) indicate that maize is moderately sensitive to water stress under the climate conditions of Serbia. The amounts of water used on evapotranspiration under irrigation (ETm ) and non-irrigation (ETa ) conditions ranged from 453 to 501 mm, and 257 to 363 mm, respectively. The values of Iwue and ETwue varied from 0.020 to 0.036 t ha-1/mm and 0.024 to 0.038 t ha-1/mm, respectively, mostly depending on the favourableness of the year for the maize production and irrigation water applied. Ky, Iwue and ETwue can be used as a good basis for maize 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.