| A greenhouse experiment was conducted to study the accumulative dynamics of grain protein, amylose and nitrogen (N) in the vegetation organs (roots, stems, leaves) after heading stage in solution-cultured rice plants of two rice cultivars treated with three N levels. Contents of grain crude protein, grain amylose, flag leaf chlorophyll and protein-N, root N, stem N and leaf N were measured.In comparison with their original seeds, the solution cultured rice Oryza sativa L. grain had strikingly higher protein content across all the cultivars and the N levels, and remarkably lower amylose content in the waxy and low amylose cultivars, which might be due to the sufficiently stable N supply and well controlled temperature and humidity. The highest grain protein content was 163.6 g kg~-1 in this experiment, which is the highest known reported rice grain protein content. The residual N concentration was greater than 12.39 g kg~-1 in the roots, 8.95 g kg~-1 in the stems, and 21.97 g kg~-1 in the flag leaves across all the cultivars and N treatments at harvesting. The rice grain had a narrow range of grain carbon (C) content and hydrogen (H) content. The average grain C content and H content for all the rice samples were 42.95±0.15 g kg~-1 (n=60) and 6.81 ±0.04 g kg~-1 (n=60), respectively. The solution cultured rice grain was characterized with lower C/N mole ratio and lower H/N mole ratio, which could be mainly attributed to the increased protein content. The results in this study suggested that solution culture technology could improve the production potential of rice.In comparison to their original seeds, the solution cultured rice Oryza sativa L.grain had strikingly lower albumin and globulin content and remarkably higher prolamin and glutelin across all the cultivars and the N levels. The grain albumin content of solution-cultured rice and the seed grain ranged from6. 97 gkg"1 to 13.46gkg ' and 9. 38 gkg"1 to 11.52gkg"', the globulin content ranged from 4.86 gkg'1 to 9.32gkg"' and 6.44gkg"' to 8.93g kg"', the prolamin content from 6.12gkg"' to 14.36gkg"' and 3.17 gkg"'-6.62 gkg"',and the glutelin content from 93.0gkg"' to 138.38gkg"' and 43.38 gkg"1 to 65.54 gkg'1. It suggests that the technology of solution culture not only increases the protein content, but improves the protein quality of solution-cultured rice.The flag leaf chlorophyll content is the lowest at milk stage among the four investigated growth stages (heading, grain-filling, milk and ripening), and lowest at grain-filling. The flag leaf protein-N content is also lowest at milk stage, but it's highest at heading stage. Stem nitrogen content decreased after heading stage. From heading stage to filling stage, nitrogen concentrations in the roots and the leaves decreased, then increased at milk stage and decreased once again at ripening stage. The grain crude protein content in the solution-cultured rice stage was the highest at milk among the three dates investigated (filling, milk, and ripening), with the highest being 163.6gkg"\ The results indicated that solution-culture technology could provide raw rice material of high protein content for food industry. The grain amylose content increased from filling stage to milk stage, then decreased at ripening stage. The grain protein contents and the nitrogen contents in the vegetation organs (roots, stems, leaves) after heading stage were significantly {0.01 level) lower at deficient nitrogen level than that at normal N level and high N level.
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