The Effect of Drip and Sprinkler Irrigation Systems on Yield and Water Productivity of Rice in Transplanting and Direct Cultivation Methods

Rice is the second most important edible grain after wheat in Iran. The most important factor for sustainable production in rice production lands, is water. Almost 75 percent of the world's rice is produced from paddy fields and rice is the largest consumer of water among all crops. Its growth is significantly affected by climate change and water scarcity. This research was carried out to compare the direct cultivation and transplanting of rice under different irrigation methods from the point of view of water productivity. The current work was designed as split plot based on randomized complete block design with 6 treatments and three replications in 18 plots with 6 m wide and 12 m length (72 m 2) in area of approximately 1500 m2 at the Agricultural Research Station of Golestan province in spring and the summer of 2018. Treatments including three levels of basin irrigation, sprinkler and drip (tape) irrigation were considered as main factors and two methods of direct cultivation and transplanting were considered as sub-factors. The results of analysis of variance showed that the effect of irrigation and sowing method on the yield of rice were significant at 0.01 level probability. The highest amount of biological yield in transplanting was obtained by basin irrigation (8177 kg/ha) and in direct seeding in basin irrigation and taper irrigation (7375 and 6836 kg/ha, respectively). The highest 1000-grain weight in transplanting method was obtained in basin irrigation and direct seeding method in traditional irrigation and tape irrigation. The highest number of filled grains in the panicle was observed in the basin irrigation treatment in transplanting, with significant difference compared to the amount observed in direct seeding. Traditional irrigation between planting methods had not significant effect on the number of hollow grains; while in sprinkler and tape irrigation (with an average of 51 and 56 for sprinkler and tape irrigation, respectively), the number of hollow grains had a higher rate in direct seeding (with an average of 41 and 45 for sprinkler and tape irrigation). The results showed that basin irrigation with 8177 kg/ha grain yield in transplanting method and basin and tape irrigations with 7375 and 6836 kg/ha in direct seeding method had the highest grain yield. Sprinkler irrigation had the lowest paddy yields in transplanting (4188 kg/ha) and direct seeding (5712 kg/ha). Tape irrigation with 7390 and 6840 m3 of consumed water, resulted in lower water consumption compared to traditional irrigation (10700 and 1693 m3), respectively. The highest amount of water use efficiency was obtained in direct and tape irrigation (0.99 kg/m3) and in traditional and tape irrigation (0.76 and 0.66 kg/m3, respectively). Adjusting water consumption both through lower water consumption and reduced water wastage can lead higher water productivity of rice production systems creating sustainable rice production systems. In transplanting method, tape irrigation and traditional irrigation had higher water use efficiency than sprinkler irrigation, although a significant water use reduction in tape irrigation rather than basin irrigation should be analyzed economically at real water prices. Overall, in this study, the tape irrigation method, by reducing water consumption, was able to increase water productivity and maintain the yield of rice in direct cultivation. Sprinkler irrigation had the lowest yield of rice in transplanting and direct cultivation. Problems such as lack of uniformity of spraying and waste water through the wind as well as poor quality of sprinklers are the main reasons for the decrease of the efficiency of sprinkler irrigation.