Dynamical partition of photosynthates in tillers of rice (Oryza sativa L.) during late growth period and its correlation with feeding value of rice straw at harvest

This study was to investigate the dynamical partition of photosynthates in panicle-removed tillers of rice (Oryza sativa L.) during late growth period and its correlation with the feeding value of rice straw at harvest. Four rice cultivars (Liangyou 108, Huaidao 6, Nanjing 43, Nanjing 44) were cultivated in Nanjing under the same management of Jiangsu area, and were sampled from weeks 1 to 5 after anthesis and at harvest in 2008, 2009 and 2010. Then, the content of nonstructural carbohydrates (NSC), hemicellulose, and acid detergent fiber (exclusive of residual ash, ADFom) in tillers were determined. The crude protein (CP) content in tillers at harvest was assayed in 2009 and 2010. Freehand sections of the fourth internode of main culm were made to visualize the starch particles in parenchyma cells in week 1, 3 and 5 after anthesis in 2010. The results showed that the content of NSC decreased sharply from week 1 to 3 and then increased to week 5 after anthesis; hemicellulose in week 5 remained at an approximate level with that of week 1; ADFom increased slightly from week 1 to 3, and then stayed constant till week 5 after anthesis. The starch particles in parenchyma cells of stems decreased from week 1 to 3 and increased slightly till week 5 after anthesis again. The rebounding rate of NSC (NSCRR) was positively correlated with the content of NSC and CP at harvest while negatively correlated with the content of hemicellulose and ADFom at harvest.