Soil and crop management. Soil fertility management: microbiological studies. Molecular nitrogen fixation associated with the rice plant. Relative contribution of roots to nitrogen fixation associated with wetland rice
Annual Report for 1978: 245
The relative contribution of roots and stems to total N fixation was studied by the acetylene reduction assay (ARA) in rice (a) IR26 and (b) Latisail grown in the field and transferred to N-free sol. culture for 1 day; rates were measured for 5 and 24 h for rootless and intact plants. Rates for rootless plants were always higher than those for intact plants in the 24-h assays, suggesting that rates for the former increased during growth after the roots were cut. It was suggested that the 5-h assays may therefore be a more realistic evaluation of N fixation by roots. In 5-h assays the relative contributions to ARA rates by stems was 6-100%.