Effect of Surface and Subsurface Drip Irrigation Systems on Yield, Yield Components, and Water Productivity of Rice

Due to the drought, water and food security in the country is facing serious challenges, and a precise and science-based implementation plan is needed. The use of new technologies, such as modern irrigation systems, is essential as an effective tool for optimal water use. Therefore, this study was conducted to investigate the yield, yield components, and water efficiency of rice variety "Honda" in two surface and subsurface drip irrigation systems in a paddy field located in Kiasar, Mazandaran Province, Iran, during the spring and summer of 2022. The experimental design was strip plots using a randomized complete block design with 6 treatments and 3 replications in 18 plots measuring 2 by 3 m. The treatments included surface drip irrigation with strip distances of 25, 50, and 75 cm, and subsurface drip irrigation at a depth of 30 cm with the same strip distances. The results showed that cluster length, number of grains, plant height, and root length were significantly increased in surface drip irrigation treatments compared to subsurface treatments, with an increase of 1.2 cm (6.8%), 8.19 (49.8%), 6.9 cm (8.2%), and 1 centimeters (6.9%), respectively. The grain yield, harvest index, physical efficiency, and economic efficiency in the surface drip irrigation treatments showed significant increases of 1664 kg/ha (40.8%), 4.7% (14.1%), 0.27 kg/m3 (38.5%), and 242,363 Rials/m3 (38.4%), respectively, compared to subsurface drip irrigation treatments. The maximum grain yield and harvest index were observed at distances of 25 cm, equal to 5834 kg/ha and 40%, respectively. The maximum physical efficiency was observed at a distance of 50 cm, equal to 0.93 kg/m3. With an increase in distance between the strips from 25 to 50 cm, the physical efficiency increased by 22%. However, further increase in the distance led to a decrease in physical efficiency. The maximum economic efficiency was observed for surface drip irrigation at a distance of 50 cm, equal to 836,951 Rials/m3.