Effects of Nitrogen Fertilizer on the Starch Structure, Protein Distribution, and Quality of Rice

Abstract

As an important cultivation measure, nitrogen fertilizer application can improve the rice yield, but it also reduces the eating quality of rice. Since protein and starch are the most important chemical substances in rice, protein and starch determine the eating quality of rice. It is unclear how nitrogen fertilizer application affects protein and starch and then affects rice eating quality. Our results showed that, with the increase in the nitrogen application level, the milling quality of rice gradually increased, but the eating quality of rice gradually decreased. Nitrogen fertilizer greatly increased the protein content of the outer layer of rice and decreased the short-range ordered structure of starch. The relative crystallinity of starch and the proportion of large granular starch first decreased and then increased. The changes of protein distribution and starch structure inhibited the gelatinization of starch gel and reduced the peak viscosity of starch. Nitrogen fertilization resulted in more protein interacting with starch and reduced the rice eating quality.