Two to three-fold variation in net assimilation rate (NAR) at 20–30 and 30–40 days after planting (DP) was evident among 58 elite rice varieties under field conditions during summer season. NAR was associated positively with specific leaf weight (SLW), relative growth rate and dry matter after the particular stage and negatively with leaf area ratio and inherent duration of the variety. The elite culture, C-1907 (Swarnaprabha) and a trdaitional check, Ptb 10 showed high efficiency in both NAR and dry matter production at 40 DP. SLW is considered to be an useful primary index of selection for higher NAR rice varieties at the vegetative growth stage.
