Abstract:This paper concerns the photosynthetic characteristics of a yellow-greennucleus mutant ofricewhich was obtained in anther culture by us. The contentof total chlorophyll, xanthophyll and β-carotene in the mutant leaves is about 31%, 40% and 75% of that ill normal leaves respectively; the chl a/chlb ratio of the mutant is much higher than that of normal leaves. The anal-ysis of SDS-solubilized extracts of the chloroplast lamellae shows that themajor light-harvesting chl a/b protein complex of the mutant is extremelydeficient, and its chl a/chl b ratio is more than 3. In the chloroplasts ofmutant leaves, there are very few grana stacking, and more starch grainscan be seen when leaves are exposed to sun light. The rate of CO2 assimilationof mutant leaves exposed to 20000 lux of sun light is 75% of that of normalleaves on a basis of leaf area, and is 185% on a basis of chlorophyll. Thechloroplasts of the mutant may also show a much higher rate of ferricyanideHill reaction on a basis of chlorophyll.