1. Dart, P. J., Day, J. M. and Harris, D., Assay of nitrogenase activity by acetylene reduction. FAO/IAEA Technical Report No. 149, ?Use of isotopes for study of fertilizer utilization by legume crops?, 85?100 (1972).
2. Heinrichs, D. H., Flooding tolerance of legumes. Can. J. Plant Sci. 50, 435?438 (1970).
3. Hensen, I. E. and Wheeler, C. T., Hormones in plants bearing N fixing root nodules. The distribution of cytokinins in Vicia faba L. New Phytol. 76, 433?439 (1976).
4. Huang, C. Y., Boyer, J. S. and Vanderhoff, L. N., Acetylene reduction and metabolic activities of soyabean having various leaf and nodule water potential. Plant Physiol. 56, 225?227 (1975).
5. I.I.T.A., Annu. Rep. Farming Systems Program, International Institute of Tropical Agriculture, Nigeria, 82 pp (1973).