Abstract: This paper analysed the grain protein content and amino acid composition of 382 cultivated rice varieties including Hsien (Indica), Keng type (Japonica) rice and upland rice. The results were as follows;The protein content (N×5.95) of rice cultivars ranged from 7.01 to 17.86% and the average value was 10.48%. The protein average content of Hsien rice varieties was higher than that of Keng rice growing under the same conditions.The protein content in brown rice of the same variety varied grown under different enviromental conditions. The result also indicated that protein content of rice was increased by sewage water irrigation.The correlations between the protein content of varieties and growth duration as well as grain weights were negative.All protein varieties contained comparatively less limiting amino acids. In general, lysine and threonine were found to be the first and second nutritionally limiting amino acids.

Key words: Rice, Upland rice, Protein, Lysine, Threonine, Nutritional quality