EFFECTS OF IRRIGATION AND NITROGEN ON YIELD AND WATER PRODUCTIVITY IN COMMON BEAN (PHASEOLUS VULGARIS L.) AND COWPEA (VIGNA UNGUICULATA L.) IN NORTH OF IRAN

Water is known as a critical and rare source that humans and ecological systems depend on. With growing population and developing technologies in many countries, availability to this critical source has been decreased. This research was conducted in a split plot experiment in a randomized complete block design with 3 replications in Iran (the north of Iran, Astaneh-ye-Ashrafiyeh). The main treatments were irrigation with 40, 60, 80 and 100% water requirement using water balance and direct method and the second treatments were 0 and 30, 60 and 90 kg N ha(-1), and two bean cultivars were tested (local Dehsari and Cowpea). Seed yield in 2016 and 2017, in the case of irrigation with100% water requirement and 60 kg N ha(-1 )was higher in common bean cultivar than in Cowpea and yields were 3486 and 3646 kg ha(-1), respectively. The highest water use productivity in seed yield in 2016 and 2017 was in common bean cultivar, and in the case of irrigation with 100% water requirement and 60 kg N ha(-1) fertilizer added, levels were 0.70 and 0.69 kg m(-3), respectively.