Experiment was conducted to study the effect of low photon flux densties(PFD) on photosynthetic rate, growth and yield in two groups of rice gentoypes differing distinctly for their assimilation rates (NAR). Reduction in PFD decreased all the growth, yield and photosynthetic characters. High NAR genotypes maintained relatively high grain yields by virtue of their high harvest index, total dry matter (TDM) and photosynthetic rates at any given level of light intensities. Descreased light intensity increased the leaf area in high NAR genotypes whereas in case of low NAR genotypes the leaf area was decreased with a reduction in light intensity. This study suggests that, selection of rice genotypes with high photosynthetic rates under normal light shall be able to realise higher productivity under low light conditions as well.
