Biological nitrogen fixation (BNF) has become important in rice farming systems because this process diminishes the need for expensive chemical fertilizers which have been associated with numerous health and environmental problems. The extensive exploitation of BNF would provide economic benefits to small farmers, avoiding all malign influences of chemical fertilizers. Meanwhile, advances in biotechnology have brought rice genetics to the threshold of new opportunities for increasing rice production. This volume focuses, in six different sessions, on the role of BNF in the improvement of rice production in the light of the current state of the art of BNF technology transfer and diffusion. New ideas on BNF technology in research, extension information and inoculant technology are also included, together with the socio-economic impacts of using BNF in rice farm systems.

Introduction: Some comments about a better use of biological nitrogen fixation in rice cultivation.- 1. Rhizobial biofertilizers: the most promising BNF technology for increased grain legume production in Bangladesh.- 2. Effect of heavy metals on legume-Rhizobium symbiosis.- 3. Effect of straw incorporation on soil N-pool in submerged rice.- 4. The use of organic residues in increasing crop production in a wheat-mungbean-T. Aman cropping system on red-brown terrace soils.- 5. Leguminous green manures in rice-based cropping systems.- 6. Use of green manuring crops in rice fields for sustainable production in Bangladesh agriculture.- 7. Prospect of dhaincha (Sesbania rostrata) intercropping with T. Aus in a T. Aus-T. Aman cropping pattern.- 8. Pedology of the rice soils of Bangladesh.- 9. Does Azolla have any future in agriculture?.- 10. Utilization of Azolla in rice production in West Africa: potentials and constraints.- 11. Cultivation and uses of Azolla in Egypt.- 12. Estimation of nitrogen fixation in Azolla-rice association using 15N isotope dilution.- 13. Prospect and potentiality of cyanobacteria as an alternative source of nitrogen fertilizer in Bangladesh rice cultivation.- 14. Contribution of cyanobacterization to rice growth and performance under different field stand densities and levels of combined nitrogen.- 15. Ecological aspects of cyanobacteria from the rice fields of Corrientes (Argentina).- 16. Contribution of biological nitrogen fixation to rice production in a Mediterranean rice field.- 17. Enrichment of indigenous blue-green algal population in rice fields and evaluation of its effect in rice culture.- 18. Abundance and isolation of nitrogen-fixing bacteria from the major rice soils of Bangladesh.- 19. Burkholderia vietnamiensis, a newnitrogen-fixing species associated with rice roots, isolated from an acid sulphate soil in Vietnam: plant-growth-promoting effects on rice.- 20. SpecifiCity of root colonization by symplasmata-forming Pantoea agglomerans.- 21. Nitrogen fixation by Azospirillum brasilense isolated from rice fields of Bangladesh.- 22. Biotechnological aspects of diazotrophic bacteria associated with rice.- 23. Azospirillum phylogeny based on 16S rRNA sequences.- 24. Increased growth and yield of rice by treating seeds and spraying plants with non-nitrogen-fixing bacteria.- Title of papers published in the symposium abstract.