Investigating the Effect of Irrigation Interval in Strip Drip System on Rice Yield and Soil Salinity Changes with Direct Seeded Rice in Dry Bed in Khuzestan Plain, Iran

Rice is one of the most important summer crops in Khuzestan Province. Due to the severe water limitation, the effect of using strip drip system in the method of direct seeded rice in dry bed was monitored on the yield of common rice cultivars of the province and changes in soil salinity. This research was conducted during 2019-20 and 2020-21, at the Ahvaz Agricultural Research Station on three adjacent plots of land, using split-plot design and randomized complete blocks in three replications. The main factor was irrigation including three levels: daily irrigation, every two days, and three days; and the secondary factor included three cultivars (Red Anbori, Champa, and Daniyal) and one salt tolerant rice line (S2). In the first year, due to the allocation of water outside the cultivation date, the yield of the crop was very low, so, the analysis was done based on the second year. The average volume of irrigation water in the field was measured as 14,800, 15,200, 15,700 and 16,100 m3/ha for, respectively, line S2, Red Anburi, Daniyal, and Champa. The results showed that, in the daily irrigation, the "Red Anburi" local cultivar had the highest yield with 3767 kg/ha and S2 line had the lowest 2541 kg/ha, so that when the irrigation changed from every day to three days, the yield decreased by 56% on average. The highest water productivity was obtained by the "Red Anburi" cultivar (0.25 kg/m3) in the daily irrigation. The reason for this problem can be shown in the monitoring of soil salinity, so that with daily irrigation, the salinity of the saturated extract in all soil layers showed a decreasing trend from 3.77 to 1.8 dS/m. According to the results, use of drip irrigation system would significantly reduce the volume of irrigation water compared to "conventional puddled transplanted rice". This has been an effective strategy in reducing the stress on the water resources of the province and saving the available water to preserve the ecosystem, although significant reduction of rice cultivation area in this province is recommended.