Rising atmospheric carbon dioxide on grain quality in crop plants.

There is a general concern that changes in plant productivity and composition caused by increase in atmospheric CO2 concentration will alter the chemical composition of the grain. This review describes the impact of rising atmospheric CO2 on the grain characteristics in wheat, rice, brassica, mungbean and soybean, which are significantly responsive to the elevated CO2 for their growth, physiology and biochemical processes. The synthesis of the CO2 induced changes in the chemical composition and nutritional qualities of their grains has been discussed. It was demonstrated that the rise in atmospheric CO2 affects the nutritional and industrial application properties of the grains of crop plants. The grain proteins and other nutritionally important constituents significantly reduced, adversely affecting the nutritional and bread making quality in wheat. However, there are evidences suggesting the sustenance of the bread making properties by fertilizer application. Similarly, the CO2 induced changes in the composition of starch in rice grains, result into easy gelatinization and higher viscosity on cooking. These grains bring firmness due to increase in amylose content. Adequately larger size of grains was the outcome of the elevated CO2 effects, in Brassica species. It increased the oil content due to greater acetyl Co A enzyme activity and also help in regulating fatty acid biosynthesis. Some of the nutritionally undesirable fatty acids were significantly reduced in this process, making this oil less harmful for heart patients. The adequate use of fertilizer application and selection pressure of breeders may significantly contribute in developing cultivars, which will counter the adverse effect of rising atmospheric CO2 on grain quality.