Comparison of evapotranspiration between continuous flooding and shallow water depth irrigation in different rice varieties of Indonesia

Lowland rice field with continuous flooding irrigation is the predominant rice cultivation system in Indonesia which need high demand of water. Nowadays, water scarcity and climate change issues need to be address with new technology to increase water use efficiency in rice production. This study aims to compare rice seasonal evapotranspiration between continuous flooding (CF) and shallow water depth (SWD) irrigation in different rice varieties. Pot experiments were conducted during rainy season in 2018 at screen house Faculty of Agricultural Technology, Universitas Gadjah Mada, Indonesia. Three different rice varieties, Hitam, Mutiara, and IR 64 were used in this experiment. Daily reference evapotranspiration (ETo) was estimated using Penman-Monteith equation and the weather variables were collected at the site by an automatic weather station. Irrigation water input were monitored every day and actual crop evapotranspiration (ETa) was determined by using water balance method. ETo during plant growth season was varied from 1.78 mm/day to 3.46 mm/day with average value of 2.64 mm/day. Rice daily ETa was varied among irrigation treatments and rice varieties. ETa of Hitam variety under SWD was varied from 0.90 mm/day to 5.47 mm/day and under CF was 0.71 mm/day to 6.36 mm/day. IR64 under SWD was varied from 1.51 mm/day to 4.20 mm/day and under CF was 0.85 mm/day to 6.51 mm/day. Mutiara was showed higher ETa than Hitam and IR64 both in SWD and CF irrigation with value ranged from 1.46 mm/day to 4.99 mm/day for SWD and 1.13 mm/day to 8.63 mm/day for CF.