Potential evapotranspiration of winter wheat in the conditions of south Serbia

Abstract Variable climatic conditions during vegetation in our country, where precipitation vary by amount and schedule, show a very great effect on winter wheat grain yield and quality. Establishing crop water requirements (ETc) is an initial foundation for reaching grain yield adequate to high genetic potential of modern cultivars. The trials were set at 198 m of altitude, 43o19' N of latitude and 21o54' E of longitude, in random complete block design (RCBD) with five replications. Trials included three irrigation variants with pre-irrigation soil moisture of 60%, 70% and 80% of FWC, as well as unirrigated control. Water used on evapotranspiration of winter wheat (289.5-410.7 mm) was measured by water balance method. Considering average for both investigated years, the highest grain yield of winter wheat was observed at the variant with pre-irrigation soil moisture 70% of FWC (7110 kg ha-1 and 7480 kg ha-1), so measured values of ET at this variant from 381.1 to 393.1 mm represented potential evapotranspiration (PET) of winter wheat in southern Serbia. Calculated requirements for water of winter wheat by CROPWAT model for the season 2009/10 was 409.9 mm, while in the season 2010/11 calculated water consumption amounted 432.6 mm of water. Efficient use of CROPWAT model for calculation of winter wheat water requirements is possible, if calibration of crop coefficients (Kc) for agroecological conditions of southern Serbia is previously carried out.