Effect of increasing of atmospheric CO2 concentration and nitrogen on growth and uptake of nutrient in wheat

Population growth and increased industrial activity in the last two centuries have led to a significant increase in atmospheric CO2 concentration. According to research, the atmospheric CO2 concentration has been increasing constantly since the industrial revolution up to recent years. The concentration has increased from 270 mg/l before industrial revolution in the mid eighteen century to about 394 mg/l in 2013. Effects of elevated CO2 concentration on uptake of plant nutrients such as nitrogen, iron, manganese, and zinc, on many agricultural crops have been studied. Improvement of nutritional conditions due to use of nitrogen fertilizers and increasing atmospheric CO2 concentration initiating increased photosynthesis and dry matter production results in promoting growth and yield increase of agronomic crops. At the same time this would change the concentration of necessary nutrients in the plants. This research is conducted with aim of studying effects of elevated CO2 concentration and nitrogen availability on plant nutrient uptake in wheat.
A greenhouse experiment in a factorial (combined) based on completely randomized design was conducted with soil texture in two levels (sandy clay loam and sandy loam), nitrogen in three levels (0, 100 and 200 mg/kg from urea source) in 4 replications of each treatment. Treatments were applied under two CO2 levels (ambient 400 and elevated 850 mg/l). A total of 24 pots in each CO2 level and 48 pots in total were used. Sixty days after planting, the aboveground parts were harvested and plant dry matter weight, nitrogen, phosphorus, potassium, iron, manganese and zinc in shoots were determined and compared.
results showed that with increasing CO2 concentration, in different nitrogen treatments shoot dry weight of wheat increased on the average by 10.67 percent. Increase in CO2 concentration did not have significant on shoot nitrogen and magnesium uptake of wheat but increased phosphorus, potassium, iron, manganese and zinc uptake by 18.58, 20.72, 32.87, 24.66, and 22.36 percent, respectively. Application of nitrogen fertilizer increased shoot uptake of nitrogen, phosphorus, potassium, magnesium, iron, manganese and zinc by 337, 93, 96, 145, 135, 129 and 156 percent, respectively, and this increase was more intense for phosphorus, potassium, iron and manganese in elevated CO2 concentration.
The amount of chemical fertilizers, especially nitrogen, and nutrient balance should be changed according to the weather conditions. Based on the results of this experiment, increasing soil nitrogen concentration resulted in an exacerbation of the positive effects of increasing CO2concentration. Therefore, if there is no limitation in the supply of essential nutrients, especially nitrogen, wheat growth and shoot uptake of most nutrients will increase under increased atmospheric CO2 concentration.