The Effect of Water Stress Using Line Source Sprinkler Irrigation Method on Soybean Yield

Water is an important factor in crop production، and is of a high value in agricultural Engineering. Water shortage is the most restricting factor in irrigated areas. Because of quality and quality limitation، deficit irrigation research has a special value in water use optimization and determination of water depths indexes inirrigation strategy. Thus، a determination of the water-yield relationship is essential. This study was carried out in Gorgan region to evaluate the effects of water stress on yield and water use efficieny of soybean in six levels of irrigation (is1-is6) for Sepideh variety in six replications using line source sprinkler irrigation method. Yield function for was derived as (Y=-0. 0528x2+54. 907x-3073. 5، R2=0. 93). Under full iriigation، the sepide cultivar need 354. 9 mm of water to produce maximum yield of 10190 kg/ha. Maximum and minimum of water use efficiency were obtaibed 16. 0 and 35. 3 kg/ha. mm at IS1 and IS4، respectively. Average grain yield and number of pods per plant were increased by increasind water depth. Minimum of grain yield، number of pods per plant and thousand grain weight were obtained in Is1. FAO water stress index (Ky) was obtained 0. 94. Ky was derived 0. 92. The comparison between the ky of cultivated soybean cultivars at Golestan province showed that katool cultvar has the more suitable response to water deficit than sahar and G3 cultivars to increase yield and optimal use of limited water resources.