Effect of CO2 concentration and soil nitrogen availability on physiological and growth indices of wheat

Increase of CO2 concentration and nutritional improvement resulting from the consumption of nitrogen fertilizer commonly increases the photosynthesis and growth of crops. This study aimed to investigate the effect of CO2 concentration and nitrogen supply on growth and physiological characteristics of wheat of Chamran variety. A factorial experiment (combined) based on completely randomized design with soil texture in two levels (sandy clay loam and sandy loam), nitrogen in three levels (0, 100 and 200 mg kg-1) in 4 replications were conducted which treatments were applied under two carbon dioxide levels (ambient 400 and elevated 850 ppm). The results revealed all the growth characteristics (except root dry weight) in the sandy clay loam soil were higher than sandy loam. Increase of the amount of soil nitrogen significantly increased growth characteristics and also increased physiological characteristics. With the increase of CO2 concentration growth parameters such as height, shoot fresh and dry weight, root dry weight and leaf area and also the RWC as well as plant physiological parameters were significantly increased. With increasing concentrations of CO2 associated with the consumption of nitrogen fertilizers vegetative indices significantly increased. In other words, increasing amount of soil nitrogen would intensify the effect of increasing concentrations of CO2. Therefore, if there is no limitation in the supply of essential nutrients, especially nitrogen, wheat growth will increase under elevated CO2 concentration.