Effect of Deficit Irrigation on Yield, Yield components and Water Productivity of Soybean T.215 Cultivar

In order to evaluation the effects of irrigation levels on yield، yield components and water productivity of soybean T. 215 cultivar، an experiment was conducted based on Randomized Complete Block Design with three replications at Agricultural Research Farm، Faculty of Agriculture، University of Guilan in 2009. The treatments were included four irrigation levels based on potential moisture 30-35 (I1)، 50-55 (I2)، 70-75 (I3) Centibar soil using Tensiometer and without irrigation (I4). The studied traits were included plant height، No. of nodes in main stem، No. of branches per plant، height of first pods from ground level، pod length، No. of pods per plant، No. of seeds in per pod، 1000 seed weight، seed yield and oil and protein content. Water productivity indices were also calculated. The results showed that deficit irrigation significantly reduced seed yield (Water deficit stress by reducing yield components decreased yield of soybean). The highest and the lowest value of the seed yield obtained by I1 and I4، respectively and also these two of treatments showed the highest and the lowest water productivity، respectively. So، according to the results of the present experiment، irrigation based on I1 treatment was recognized the best treatment in view of seed yield and water productivity. The results of correlation analysis showed high correlation between seed yield and No. of pods per plant (r=0. 985**). The results of stepwise regression also showed that No. of pods per plant was the most important yield component and covered the most of total yield variance.