A dwarf rice mutant was induced through the chronic exposure of 60Co gamma-rays. This mutant was crossed with a heavy-panicle type variety, and semi-dwarf plants permitting a more efficient distribution of light within the canopy were obtained. They along with current commercial varieties and the parent mutant were assessed for yield components, the yielding ability at three levels of nitrogen fertilizer by varying plant density and several other agronomic traits. The ssmidwarf rice possessed significantly higher rates of net photosynthetic CO2 uptake compared with that of current commercial varieties, and it was improved in yield return by increasing nitrogen application. Manner of display of leaves could be manipulated by induced mutations.
