Impact of Elevated CO 2 on Two Successive Generations of CO 2 Responsive Maize Genotype

A CO 2 -responsive maize ( Zea mays L.) genotype, Harsha, was selected to assess its response to elevated CO 2 in successive generation. The selfed seeds harvested from elevated CO 2 (eCO 2 ) raised maize plants were sown in open-top chambers (OTCs) to raise second generation (H-II) plants along with fresh seeds as first generation (H-I) under both ambient (400 ppm) and elevated (550 ppm) CO 2 (eCO 2 ) conditions. It was observed that second-generation (H-II) plants also showed improved performance under eCO 2 for morphological and physiological parameters. It is pertinent to mention that the H-II plants were more vigorous even under ambient CO 2 (aCO 2 ) condition as compared to H-I plants. The vigor of H-II plants was higher for majority of the morphological and biomass parameters under both aCO 2 and eCO 2 . In H-II, the increased photosynthetic rate (Anet) was 6% and decrease in transpiration rate (Tr) was 49%, which resulted in significant increase (110%) in water use efficiency. This reveals that the elevated CO 2 improved the physiological performance of the maize plant over the generations. These results clearly elucidate that a C 4 crop like maize can respond to elevated CO 2 and higher response in subsequent generations may favor the crop resilience under changed climatic conditions.