EFFECTS OF SUPPLEMENTARY N ON THE QUALITY AND LEVELS OF GRAIN PROTEINS IN RICE

The effects of supplementary URAN-N (urea-ammonium-nitrate), applied either to the soil or as a foliar spray, on dry weight, crude protein level and main protein fractions of rice (Oryza sativa L.) grain were studied under greenhouse conditions. URAN (20 kg of N/ha) applied at different times before, during and after anthesis, increased crude protein levels in grains. Later URAN applications caused larger protein increases. No difference in crude protein level were observed between foliar spray and soil applied URAN. A negative correlation was found between crude protein level and grain weights. The levels of albumin+globulin were not affected by N applications. Glutelin was the fraction that contributed most to the protein increase in grains. A negative correlation was found between the levels of prolamin and glutelin, showing that increases in protein levels due to supplementary N results in increase in the protein quality of rice grains.