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Enhancing field scale water productivity for several rice cultivars under limited water supply

Jonubi, Roza, Rezaverdinejad, Vahid, Salemi, Hamidreza
Paddy and water environment 2018 v.16 no.1 pp. 125-141
crop production, cultivars, deficit irrigation, drying, experimental design, field experimentation, irrigation management, irrigation water, model validation, models, paddies, rice, water supply, Iran
Rice production is one of the largest consumer of water in agriculture. In general, the irrigation water productivity (WPI) is low in paddy fields. In order to improve WPI, a field experiment was conducted in central of Iran during 2009–2010. The experiment was consisted of three irrigation managements and eight advanced rice cultivars (Gerdeh (V ₁), Zayande-roud (V ₂), Sazandegi (V ₃), Hasani (V ₄), 67–97 (V ₅), 67–113 (V ₆), 67–47 (V ₇), and 67–72 (V ₈)) in a split plot design with three replications. The irrigation treatments were I ₁ and I ₂: permanent flooding under 3.5 and 2.2 cm water depth, respectively, and I ₃: 0–1.5 cm alternative wetting and drying. To explore deficit irrigation for improved WPI, SWAP model was calibrated using intensive measured data for the foregoing years. The average normalized root-mean-square deviation of yield during calibration was 0.03% and during validation was 4.94% indicating acceptable calibration and validation of the model. WPI for all cultivars were enhanced up to 61% by applying 50% deficit irrigation. On this irrigation regime, V ₂ and V ₆ provided the highest WPI (0.84 and 0.79 kg m⁻³, respectively) whereas V ₄ and V ₈ yielded the lowest (0.50 and 0.57 kg m⁻³, respectively). The results indicated that rice cultivars (V ₂ and V ₆) are the best option with the highest WPI in the irrigation district and calibrated model was able to effectively simulate the crop growth under water deficit conditions.