Characteristics of nutrient accumulation and partitioning in yield formation process of different rice cultivars

N accumulation and distribution in three different rice cultivars:“Shanyou 63”(three-line hybrid rice),“Liangyou 2186”(two-line hybrid rice)and“IR 64”(traditional rice) were studied by determining the dynamics of N, P and K contents in different parts of the rice cultivars. Results show that nitrogen contents in the cultivars decline throughout the growing stages and nitrogen content in“Shanyou 63”is the highest among the three rice cultivars at the same developmental stages. The same trend is found for K content,except that a significant increase is observed in“Shanyou 63”at full heading stage. P contents in the three rice cultivars are almost the highest at full tillering stage. At full maturity, the order of accumulated nitrogen in the three rice cultivars(“Shanyou 63”,“Liangyou 2186”and“IR 64”) is 24.79g/m², 15.14g/m² and 14.42g/m²; that for phosphorus is 4.766g/m², 3.306g/m² and 3.678g/m²; and that for potassium is 2.439g/m², 2.029g/m² and 1.725g/m² respectively. About 61.23% accumulated nitrogen in“Shanyou 63”is partitioned to grain, which is 17.97%,and 11.23% higher than those of “Liangyou 2186” and “IR 64” respectively. Similarly, 62.97% accumulated phosphorus in“Shanyou 63”, which is 6.41% and 9.63% higher than those of“Liangyou 2186”and “IR 64”is patitioned to grain; and 27.51% accumulated patassium, which is 3.00% and 2.39% lower than those of“Liangyou 2186” and “IR 64”, is partitioned to grain. Nitrogen requirement in “Shanyou 63”,“Liangyou 2186”and “IR 64” amounts to 31.33g/m², 22.88g/m² and 24.82 g/m² at full development stage and required NPK ratios are 1∶0.192∶0.098，1∶0.219∶0.134 and 1∶0.255∶0.120 in that order. The lowest production efficiency of N, P and K among the three rice cultivars is in “Shanyou 63”. The production efficiencies of N, P and K are 37.25kg/kg N, 193.80kg/kg P and 378.80kg/kg K for“Shanyou 63”; 52.54kg/kg N, 240.38kg/kg P and 392.16kg/kg K for“Liangyou 2186”; 58.38kg/kg N, 228.83kg/kg P and 487.80kg/kg K for “IR64” respectively. In conclusion, the three-line hybrid rice “Shanyou 63” needs much more nitrogen, phosphorous and potassium supply; shows higher nutrient accumulation and partitioning to grains as major assimilate sink, which agrees with higher grain productivity than in “Liangyou 2186” and “IR 64”. However, further study is required on the use efficiency of N, P and K. This is key to realizing higher yield and nutrient efficiency in “Shanyou 63” under optimum nutrient supply.