Two fold variation in photosytrthetic rate (26.8 to 47.8 mg CO2 dm-2 hr-1) was observed among 53 high yielding rice varieties. Cultivars Ptb 10, Co 41, Ratna, Saket 4 and Pallavi recorded consistently high photosynthetic rate (Pn) of more than 40 mg CO2 dm-2 hr-1 at vegetative (30 days after planting) and flowering stages. Stomatal diffusive conductance showed positive correlation with Pa. Pn has no correlation with dry matter or yield while photosynthetic potential expressed as product of Pn or cumulative solar radiation with leaf area index recorded high correlation with yield.
