Impact of Elevated CO2 on Two Successive Generations of CO2 Responsive Maize Genotype

Abstract

A CO2-responsive maize (Zea mays L.) genotype, Harsha, was selected to assess its response to elevated CO2 in successive generation. The selfed seeds harvested from elevated CO2 (eCO2) 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) CO2 (eCO2) conditions. It was observed that second-generation (H-II) plants also showed improved performance under eCO2 for morphological and physiological parameters. It is pertinent to mention that the H-II plants were more vigorous even under ambient CO2 (aCO2) 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 aCO2 and eCO2. 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 CO2 improved the physiological performance of the maize plant over the generations. These results clearly elucidate that a C4 crop like maize can respond to elevated CO2 and higher response in subsequent generations may favor the crop resilience under changed climatic conditions.