Assimilatory function and biochemical changes in Stylosanthes hamata grown under elevated CO2

We studied the impact of 360 ± 50 µL/l (ambient) and 600 ± 50 µL/L (elevated) CO2 on growth performance, biomass production, photosynthetic efficiency, carbon isotope discrimination, protein profile and some antioxidant enzymes on Stylosanthes hamata. This crop responded significantly to photosynthetic rate, stomatal conductance and transpiration rate under elevated CO2. The biomass production in terms of fresh and dry was increased in elevated CO2 by 126.81% (fresh) and 114.55% (dry) over ambient CO2. Long term exposure to elevated CO2 enhanced photosynthetic water use efficiency by 127.77%. The photosynthetic pigment, total chlorophyll and chlorophyll a/b ratio also increased by 220.56 and 132.86%, respectively in elevated over ambient CO2. Around 149% increase in the soluble protein accumulation (mg/g FW) was recorded under elevated over ambient CO2, which was also reflected in the polyacrylamide gel profile. The isoforms of superoxide dismutase and esterase isozymes showed remarkable difference under elevated as compared to ambient. Measurement of 13δ in different plant parts indicated a significant increase in discrimination against 13C when plants were grown at elevated relative to ambient CO2. Maximum increase was recorded in roots (439.72%) followed by leaf and the stem recorded least increase in 13δ (119.94%) in elevated over ambient CO2.