اثر كاربرد كود نيتروژنه و رطوبت خاك بر كارايي مصرف آب در ژنوتيپهاي يونجه ديم

Effects of moisture and nitrogen stress on water use efficiency of dryland Medicago sativa genotypes

To investigate the effects of moisture and nitrogen stress on water use efficiency (W.U.E) of 4 cultivated perenial Medicago sativa, a glasshouse experiment was carried out. A factorial design with 3 replicationos in the basis of randomized complete block were applied. Treatments include four levels of nitrogen (0, 30, 60 and 90 kg/ha in the form of calcium and potasium nitrate), two levels of irrigation (35 and 75 percent of field capacity) and four Medicago sativa genotypes (Kerisary, Ghara Yonja, Sarbandi and Australian 2129). The results showed that water stress would affect W.U.E, evaporation efficiency, shoot biomass and Root/Shoot (R/S) ratio. Nitrogen application rates increased WUE, evaporation efficiency and shoot biomass. The highest WUE and shoot biomess were related to Gharah yonja genotype. This experiment showed that using 30 kg.ha^-1 nitrogen would be able to increase WUE and forage yield under water deficit condition. Therefore it seems that using nitrogen in early season which raining and air moisture content is favorable / would increase forage production. Gharah yonja cultivar showed better response related to adaptation and yield production.