Growth, yield and photosynthesis of Panicum maximum and Stylosanthes hamata under elevated CO2.

Plant height, biomass production, assimilatory functions and chlorophyll accumulation of Panicum maximum and Stylosanthes hamata in intercropping systems was influenced significantly under elevated CO 2 (600 ±50 ppm) in open top chambers (OTCs). The plant height increased by 32.0 and 49.0% over the control in P. maximum and S. hamata respectively in intercropping system under elevated CO 2 over open field grown crops (Ca). P. maximum and S. hamata produced 67 and 85% higher fresh and dry biomass respectively under elevated CO 2 . Rates of photosynthesis and stomatal conductance increased in both the crop species in intercropping systems under elevated CO 2 . The canopy photosynthesis (photosynthesis x leaf area index) of these crop species increased significantly under elevated CO 2 over the open grown crops. The chlorophyll a and b accumulation were also higher in the leaves of both the crop species as grown in OTC with elevated CO 2 . The increased chlorophyll content, leaf area index and canopy photosynthesis led to higher growth and biomass production in these crop species under elevated CO 2. The total carbon sequestration in crop biomass and soils during the three years was 21.53 Mg C/ha under elevated CO 2 . The data revealed that P. maximum and S. hamata intercropping system is the potential as a sink for the increasing level of CO 2 in the atmosphere in the semi-arid tropics.