Productivity of mungbean (Vigna radiata) with elevated carbon dioxide at various phosphorus levels and cyanobacteria inoculation

Increase in the concentration of atmospheric carbon dioxide (CO₂) has significant impact on crop growth and productivity. A study was undertaken during the kharif season of year 2014 to study the impacts of elevated CO₂ and cyanobacterial inoculation on growth and yield of mungbean crop under different doses of P using Free Air Carbon dioxide Enrichment (FACE) facility. The crop was grown under two CO₂ levels i.e., ambient (400 μmol mol⁻¹) and elevated (550 ± 20 μmol mol⁻¹), with five levels of P (0, 8, 12, 16 and 20 mg P kg⁻¹ soil) and 2 levels of calothrix sp. (with and without cyanobacteria) inoculation. Elevated CO₂ level increased seed yield by 35.0% and biomass yield by 31.3%. Leaf area, photosynthesis rate and leaf chlorophyll content significantly increased at high CO₂ level. Yield attributes such as number of pods plant⁻¹, number of seeds pod⁻¹ and test weight also increased at high CO₂ level. Application of P and cyanobacterial inoculation further increased growth and yield of the crop. The study showed that application of P as well as cyanobacteria could help in improving productivity of legumes under elevated CO₂ condition.