Determining the performance of the cropgro-sunflower model in different irrigation regimes and evaluating the effect of climate change on sunflower production in Mediterranean conditions

This research was carried out to determine the performance and sensitivity of the CROPGRO V4.7.5 model in determining the effects of different irrigation programs on yield and water use in sunflower (Oleko) irrigated with drip irrigation system in Mediterranean conditions in 2010 and 2011. In the irrigation program, 3 different irrigation intervals are formed from accumulated evaporation values (CPE1: ΣEo = 25 ± 2.5 mm; CPE2: ΣEo = 50 ± 5 mm; CPE3: ΣEo = 75 ± 5 mm), 4 different irrigation levels (IL0.50 = 0.50 ; IL0.75 = 0.75; IL1.00 = 1.00; IL1.25 = 1.25). According to the results obtained; irrigation interval and irrigation level interaction was found to significantly affect total sunflower grain yield at 1% error level statistically. In both experimental years, the highest yield was recorded from CPE2-IL1.25 and the lowest yield was recorded from CPE3-IL0.50. The total amount of irrigation water applied to the subjects varied between 199mm and 578 mm while plant water consumption values varied between 243mm and 611 mm in both years. Irrigation interval and irrigation level; The yield of Sunflower significantly affected dry matter, leaf area, harvest index, water use efficiency (WUE) and irrigation water use efficiency (IWUE) values. Based on the resuts, the CPE2IL1.25 irrigation program can be recommended for high yields in the region. In the first part of the model study, the calibration and evaluation of the DSSAT CROPGRO-Sunflower model was made. Then, using the climate projection data as input in the plant simulation model, the effects of possible climate changes on sunflower yield were revealed. The data sets of 3 Global Climate Models (HadGEM2-ES, MPI-ESM-MR, GFDL-ESM2M) and RCP4.5 and RCP8.5 scenarios were used to create climate projections. The upcoming period were evaluated in three separate periods, namely near-term(KD) 2023-2040, mid-term(OD) 2041-2070, and long-term(UD) 2071-2098. To comprehensively evaluate the possible impacts of climate change, the analyzes were made in two separate categories as recommended full irrigation (CPE2IL1.25) conditions and deficit irrigation (CPE2IL1.00) under water scarcity conditions. According to the results of the study, sunflower productivity under water scarcity in Tarsus climatic conditions will increase by 6.8% and 5.0% in KD and OD periods respectively whereas decrease by 8.1% in the UD period in RCP4.5 scenario. In the RCP8.5 scenario sunflower productivity will increase by 7.1% in KD whereas decrease by 13.4% and 28.9% in OD and UD periods respectively. Similarly, In full irrigation conditions, sunflower yield is expected to increase by 7.6% and 8.2% in KD and OD periods respectively while a 2.9% decrease is expected in the UD period in RCP4.5 scenario. In the RCP8.5 scenario sunflower yield is expected to increase by 6.3% in KD while a decrease by 2.3% and 22.2% is expected in OD and UD periods respectively. The CROPGRO-Sunflower model simulation results showed that the estimated values of sunflower yield and plant growth parameters were close to the measured values. Therefore, the CROPGRO-Sunflower model can be used to accurately predict sunflower yield under different irrigation management conditions.