Response of soybean to water stress at specific growth stages

An investigation was carried out at Rimski Sancevi experiment field of Institute of Field and Vegetable Crops in Novi Sad. The aim was to determine the response of soybean to soil water deficit at specific growth stages to get more information that could improve the cropping technology of soybean in Vojvodina region, northern part of the Serbia Republic. The crop response factor (k(y)) which is the amount of yield (Y) lost per unit of evapotranspiration (ET) loss, well expresses the response of the crop to water deficit. A larger (k(y)) value indicates greater yield losses due to water deficit. It is highly important to know not only the (k(y)) values from the literature but also those determined for a particular crop species under a specific set of climatic and soil conditions. The values of yield response factor (k(y)) were derived from the linear relationship between relative seasonal evapotranspiration deficits (1-ETa/ETm) and relative yield loss (1-Y-a/Y-m). The obtained results indicate that in the climatic conditions of Vojvodina soybean is most sensitive to water stress at the stage of yield formation - pod development and pod filling (k(y) 0.46) but less sensitive at the vegetative stage (k(y) 0.33) and at the stage of flowering (k(y) 0.41). Values of (ky) in the growing period (k(y) 0.66) approved that soybean is moderate sensitive to soil water stress in the climatic conditions of Vojvodina. Obtained values of (k(y)) could be used as a good platform for soybean growers in the region in terms of optimum utilization of irrigation water and for the planning, design and operation of irrigation projects in the region.