Growth and biochemical changes of sorghum genotypes in response to carbon dioxide and salinity interactions

Abstract

In this study, the interactive effects of atmospheric CO2 concentration and salinity were evaluated on the growth of four sorghum genotypes (SG1, SG3, SG14, and SG28). For this purpose, sorghum plants were exposed to ambient (380 ± 50 µmol mol−1) and elevated (700 ± 50 µmol mol−1) CO2 concentrations under two salinity levels (1.55 and 10.55 dS m−1). Elevated CO2 increased shoot (10–25%) and root (9–26%) dry weights, the concentrations of chlorophyll a, chlorophyll b, carotenoids, and K+, and the activities of catalase, ascorbate peroxides, and superoxide dismutase but decreased those of Na+ and water-soluble carbohydrate. Increases of 14.9 and 8.6% in shoot dry weights, 14.4 and 9.6% in root dry weights were observed under the non-saline and saline conditions, respectively. While all genotypes showed increased biomass production in response to elevated CO2 under non-saline treatment, only two genotypes were positively affected by the elevated CO2 under saline condition. Moreover, the scales of increases in plant biomass were greater under the non-saline treatment. The results of this experiment showed that the response of sorghum to elevated CO2 depended on both salinity level and genotype.