Impact of elevation of atmospheric CO2 on yield and biomass partitioning in rice and wheat

To study the impacts of elevation of CO2 on rice-wheat system, a pot culture experiment and a field experiment were undertaken. The pot culture experiment was conducted in open top chambers (OTCs) with surface soils collected from a typic haplustept (IARI, New Delhi). Rice and wheat were grown as test crops at ambient (approx. 370 m mol mol-1) and elevated (600±50 m mol mol-1) levels of atmospheric CO2. Total biomass yield was increased by 32.26 and 33.83 per cent as a result of elevation of CO2 concentration in the micro climate of rice and wheat, respectively. Various plant parts differed with respect to their relative gain in yield and the relative gains in biomass of different plant parts on exposure to elevated CO2 were in the order of: Rice: Grain (48.11) > Leaves (43.97) > roots (34.95) > stem (18.80) and Wheat: Root (70.54) > Leaves (42.50) > grain (35.39) > stem (21.00). At all stages of crop growth, exposure to higher CO2 in atmosphere increased the preferential partitioning of carbon to roots both in rice and wheat.