Determining the Optimal Planting Date, Yield and Water Productivity Indicators of Wheat with the CERES-Wheat model (case study: Zayandeh Rud Catchment Area and Northwest of Isfahan Province)

The purpose of this study was to determine the yield potential of winter wheat (Triticum aestivum) in Isfahan province and the appropriate cultivation date in different regions of the province using the CSM-CERES-Wheat plant model. For this purpose, 63 main areas of wheat cultivation were selected and their soil information was entered into the model. The model was run using meteorological data for 63 soil profiles, 18 different planting dates and 15 common wheat cultivars in the province with agronomic management without water and nitrogen stress. Average biomass production potential in the study area was 26392.47± 780.99 kg ha-1, grain yield 11914.17±442.62 kg ha-1, water productivity (WP) 1.73±0.11 kg m-3 and irrigation water efficiency (WPi) was 2.49±0.30 kg m-3. WP of the eastern regions of Zayandehrud basin (Varzaneh, Kabutarabad and lenjanat) was 12.82% higher than the western regions (Fereydunshahr, Fereydan and Chadegan) and WPi for the western regions was 16.30% higher than the eastern regions. In western and northwestern regions of the province, the production portion of green water is 38.31% and in eastern regions of the province is 18.86%. therefore, it is recommended to use the capacity of green water under any conditions in the western and northwest regions in addition to planting on suitable dates. Planting dates varied for different regions depending on whether the goal was to maximize the yield or water productivity index. Suitable planting date was obtained as following: for Fereydan, Fereydunshahr and Chadegan regions 26 September to 15 October, Khansar and Tiran 26 September to 25 October, Golpayegan 5 October to 5 November, Lenjanat, Najafabad, Kabutarabad and Varzaneh 15 October to 25 November.