Introduction: Water stress is one of the most important factors in reducing yield in legumes, including beans. Providing timely water needs of plants by selecting appropriate irrigation methods can be effective on water absorption and crop production. Pinto beans are fast-growing plant, so there must be enough water in the soil to ensure their optimal growth and yield. The development of new management methods and water-saving technologies, such as deficit irrigation methods and irrigation patterns and improving water productivity are essential and water productivity is affected by seed yield and water consumption.

Materials and Methods: Therefore, the present study aimed to investigate the effect of deficit irrigation on bean yield and water productivity in two irrigation methods, furrow and tape-drip irrigation, using a split plot in a randomized complete block design with three replications at the Khomein National Bean Research Station in 2016-2018. Irrigation treatments including furrow and tape-drip were selected as the main factor and water requirement levels including 100, 75 and 55% of water requirement were selected as secondary factors. Meteorological data were received from the regional station. Before land preparation and fertilizer application, soil samples were taken from the depth of 0 to 30 and 30 to 60 cm.

Results and Discussion: The results showed that the effect of irrigation method, the effect of water requirement at the one percent level and the interaction effect of irrigation method and water requirement supply at the 5% level on seed yield were significant. The highest seed yield was observed in the interaction effect of irrigation method and water requirement with an average of 2310 kg.ha-1 in the tape-drip irrigation method and supply of 100 percent of the water requirement. The highest water productivity based on seed yield was observed in the interaction effect of irrigation method and water requirement with an average of 0.40 kg.m-3 in the tape-drip irrigation method and supply of 75 percent of the water requirement. According to the results, if the aim final is only seed yield, the water requirement of the plant should be fully met. However, if reducing water consumption and increasing water productivity is considered, the tape-drip irrigation method can be recommended with supply of 75% of the water requirement.

Conclusion: The results of the experiment indicate that deficit irrigation had a significant effect on the biomass and seed yield traits in the study area, and the full irrigation treatment allocated more values. Also, the two irrigation methods, furrow and drip-tape, had a different behavior on the yield, so that the highest seed yield was observed in the drip-tape irrigation method and providing 100% of the water requirement, which can be concluded that with suitable irrigation conditions, the number of bean seeds increased and ultimately increased seed yield in the study area. The highest water productivity based on seed yield with an average of 0.40 kg.m-3 was observed in the drip-tape irrigation method and providing 75% of the water requirement. The final recommendation, based on the results, is that if the final aim is only seed yield, the water requirement should be under full irrigation conditions and provide 100 percent of the water requirement. However, if the aim is to reduce water consumption and increase productivity, the drip-tape irrigation method can also be considered and provide 75% of the water requirement, which would be a decrease of 21.2%.