Abstract: Effects of biochar on growth and development of japonica rice seedlings and nutrient contents of substrate soil in northeastern China were ascertained to verify the application potential of biochar in rice seedling production in northeastern China cold region. On the basis of the conventional paddy soil in northeastern China with exogenous additions of biochar (5.0%-20.0%, w/w), effects of biochar on plant height, dry matter accumulation, the uptake of mineral elements (N, C, S, P, K, Mn, Zn, Cu, Fe, Mg, Ca and Na) of rice seedlings and the change of mineral element contents in substrate soil were studied in northeastern China cold area. It was found that biochar addition had remarkable effects on plant height, dry matter accumulation of rice seedlings. Plant height of rice seedlings increased by 1.2%, 5.0% and 6.0% while dry matter accumulation increased by 18.2%, 27.7% and 43.4% compared with those of the control respectively when 5.0%, 10.0% and 15.0% of biochar were applied in substrate soil. With the increase of biochar addition, uptakes of N, C, S, P, K, Mn, Ca, Na, Mg, Zn, Cu and Fe of rice seedlings presented a similar trend of first ascending and later descending. When the biochar application rate was 5.0%, the contents of mineral elements Mn, Zn and Cu arrived at the peak. When the biochar application rate was 10.0%, the content of mineral element Fe reached the peak. When the biochar application rate was 15.0%, the contents of mineral elements N, C, S, P, K, Ca, Na and Mg reached the peak. N, C, S, P, Zn, Cu, Mg and Na contents in nursery substrates all increased with the increase of biochar application. However, K and Fe contents decreased gradually, and Mn and Ca contents had no obvious change with the increase of biochar application. The results suggested that the application of biochar in the nursery substrates by 10.0%Symbolm@@15.0% could promote the growth of rice seedlings, the absorption and utilization of most mineral elements by rice seedlings, and the ability of immobilizing and maintaining some important nutrients in nursery substrates.

Key words: wheat, lodging resistance, lignin., lodging index, hemicelluloses