IMPACT OF TEMPERATURE CHANGE AND ELEVATED CARBON DIOXIDE ON WINTER WHEAT (TRITICUM AESTIVUM L.) GROWN UNDER SEMI-ARID CONDITIONS

TONKAZ, T., E. DOGAN and R. KOCYIGIT, 2010. Impact of temperature change and elevated carbon dioxide on winter wheat (Triticum aestivum L.) grown under semi-arid conditions. Bulg. J. Agric. Sci., 16: 565-575 A study was conducted to determine effects of changed daily maximum, minimum, and elevated CO 2 levels on winter wheat yield and yield components. Treatments included 0 ± 2, 4, and 6 0 C in daily maximum and minimum temperatures, and 380, 420, 460, and 500 ppm elevated CO 2 levels. CERES-Wheat model was utilized for simulations and results were used for graphical and statistical analysis. Simulations showed that change in both temperature affected yield and all simulated physiological parameters. Results indicated that when both temperatures increased by 6 0 C, yield decreased 30%, while 6 0 C decrease in temperatures increased yield by 37% (about 5000 kg ha -1 ). The same effect was observed on the other simulated parameters such as biomass, 1000 seed weight….etc. However effects of both temperature changes were not equally divided. Daily maximum temperatures were affecting simulated parameters more than minimum temperatures. On the other hand, elevated CO 2 levels also positively affected yield, grain number, leaf area, and biomass. While, elevated CO 2 levels reduced harvest index and evapotranspiration but did not had any effect on flowering date, maturity, and 1 000 seed weight. Every 40 ppm increase in CO 2 level increased yields about 150 kg ha -1 in all elevated CO 2 treatments.