Effect of Different Nitrogen Doses on the Storage Proteins and Palatability of Rice Grains of Primary and Secondary Rachis Branches

The effects of applied nitrogen (N) doses on crude protein and amylose accumulation in rice grains on primary and secondary rachis branches and their palatability were examined. The crude protein content of rice grains on both primary (PRB) and secondary rachis branches (SRB) increased with the increase in N supply showing a strong negative correlation with palatability. The correlation coefficient between protein content of the grains on PRB and SRB was –0.92 and –0.98, respectively. Although the amylose content also decreased with increasing N supply, the change was not significant oneither PRB or SRB. However, it showed a good correlation with palatability; i.e., the correlation coefficient on PRB and SRB was 0.93 and 0.84, respectively. Analysis of protein by SDS-PAGE showed that the contents of protein bodies PB-I and PB-II, were correlated with palatability, but the latter had a higher correlation. The grains on PRB showed a higher palatability than those on SRB due to the difference in the accumulation pattern of proteins and amylose. These results suggest that when breeding for varieties with good palatability, the plants with more grains on PRB should be selected and by maintaining the nitrogen level in the field, we can control protein accumulation and thus can improve the palatability of rice crop