Scientists Investigate the Nitrogen and Genotype Effects on Protein and Amino Acid Distribution in Rice

Rice is an important staple food that provides energy, protein and nutrients to consumers across the globe. Nine percent of its dry weight is attributed to protein, which is quite low compared to other cereals' protein content. The grain proteins found in rice is also lacking in lysine, an essential amino acid. Milling process also contributes to the loss of proteins. On the other hand, nitrogen has been studied to promote grain protein accumulation, but no study has been conducted to investigate the effect of varying nitrogen.

Huifeng Ning of Nanjing Agricultural University in China together with other scientists conducted field testing of six japonica rice cultivars with different agronomic characteristics. The cultivars were subjected under seven nitrogen fertilizer treatments to "examine the nitrogen effect on protein distribution in milled rice and brown rice; and identify genotypic differences in response to protein distribution as a result of nitrogen treatments."

Results showed that for brown and milled rice, proteins albumin and globulin were mainly controlled by genotype and not by nitrogen; while proteins prolamin and glutelin were highly affected by nitrogen. There were also significant differences in the reaction of milled/brown (M/B) ratios of proteins to nitrogen treatments. Compared with cultivars with large panicles, the small-panicle cultivars exhibited lower ratio and more consistency under varying nitrogen treatments. In both milled and brown rice, amino acid composition increased with increasing N rate, except for methionine, cystein and lysine. And also, nitrogen showed no significant effects on the M/B ratios of the majority of the amino acids.

Visit http://dx.doi.org/10.1016/j.jcs.2010.03.009 for the abstract.