Advertisement

Azolla: A review of its biology and utilization

Abstract

TheAzolla-Anabaena symbiosis is outstanding due to its high productivity combined with its ability to fix nitrogen at high rates. Because of this, in recent decades, countless studies have been conducted on this association, but with insufficient synthesis and coordination. This paper, therefore, attempts to review and synthesize past and recent findings concerning the biology and utilization ofAzolla in hopes that this will facilitate increased future collaborative research on this “green gold mine.” It reviews the taxonomy, distribution, morphology, physiology, and reproduction ofAzolla as well as new developments in its manifold uses.

Because of the growing concern about conservation of the environment and the need for deploying renewable, sustainable resources; the application ofAzolla as a biofertilizer on agricultural crops, in order to provide a natural source of the crucial nutrient nitrogen, can be very beneficial to the future of our planet. Besides the environmental appropriateness of the use ofAzolla, for multitudes of farmers in many parts of the world who cannot afford chemical fertilizers,Azolla application can enhance their economic status, increasing yields while minimizing costs. Due to the fact that rice paddy fields form an ideal environment forAzolla, one of its most suitable applications is on rice.

Besides its utilization as a biofertilizer on a variety of crops,Azolla can be used as an animal feed, a human food, a medicine, and a water purifier. It may also be used for the production of hydrogen fuel, the production of biogas, the control of weeds, the control of mosquitoes, and the reduction of ammonia volatilization which accompanies the application of chemical nitrogen fertilizer.

Résumé

Une haute productivité associée avec une capacité à fixer l’azote atmosphérique démontre l’importance de la symbiose entreAzolla etAnabaena. Ce fait fut responsable des multiples études conduites et de l’intérêt porté à cette association durant les dernières décénnies. Mais il semblerait qu’une synthèse ainsi qu’une coordination entre ces différentes entreprises soient manquantes. L’article présenté ici tente de rassembler et synthétiser les résultats accumulés sur la biologie et l’utilsation possible d’Azolla, tout en espérant ainsi faciliter la collaboration future entre chercheurs investigant cette “mine d’or vert.” La taxonomie, la distribution, la morphologie, la physiologie et la reproduction d’Azolla seront couverts, ainsi que ses potentiels multiples usages.

De plus en plus, la conservation de l’environnement et le besoin d’employer des ressources renouvelables de manière à assurer leur usage continu, sont des priorités importantes. L’utilisation d’Azolla en tant qu’engrais vert pour l’agriculture, dans le but de fournir de l’azote, élément crucial du cycle nutritionel, pourrait offrir une alternative bénéfique pour le future de notre planète.Azolla peut être utilisée par des agriculteurs n’ayant pas les moyens d’employer des engrais chimiques, un peu partout dans le monds, de manière responsable pour le bien de l’environnement. Son application ameliorerait leurs revenus de part son impact sur l’accroissement des rendements tout en minimalisant le coût de production. Un des exemples les plus convaincant est son utilisation pour la culture du riz, etant donné que les champs de riz représentent un environnement idéal pourAzolla.

Outre son emploi en tant qu’engrais vert pour différentes productions agricoles,Azolla peut aussi très bien être utilisée en tant que nourriture pour les productions animalières, pour la consommation humaine, comme composant pharmaceutique, ou être utilisée dans un processus de purification de l’eau. Son emploi peut aussi inclure la production d’hydrogène en tant que combustible, la production de biogaz, le controle de plantes non désirées, le controle des moustiques, ou participer à la réduction d’émission d’azote lors de l’épandage d’engrais chimiques.

This is a preview of subscription content, log in to check access.

Literature Cited

  1. Ali, M. A. &S. Leeson. 1995. The nutritive value of some indigenous Asian poultry feed ingredients. Anim. Feed Sci. Technol.55: 227–237.

  2. Anonymous. 1982. China and the West: Sharing solutions to agricultural problems. World Farm.24: 76–78.

  3. Ansari, M. A. &V. P. Sharma. 1991. Role ofAzolla in controlling mosquito breeding in Ghaziabad District villages (U.P.). Indian J. Malariol.28: 51–54.

  4. Ashton, P. J. &R. D. Walmsley. 1976. The aquatic fernAzolla and itsAnabaena symbiont. Endeavour19: 39–43.

  5. Bar, E., S. A. Kulasooriya &E. Tel-or. 1991. Regulation of nitrogenase activity by light in theAzolla-Anabaena symbiosis. Bioresource Technol.38: 171–178.

  6. Becking, J. H. 1976. Contributions of plant-algal associations. Pages 556–580in W. E. Newton & C. J. Nyman (eds.), Proceedings of the 1st International Symposium on Nitrogen Fixation. Vol. 2. Washington State University Press, Pullman.

  7. —. 1979. Environmental requirements ofAzolla for use in tropical rice production. Pages 345–373in International Rice Research Institute, Nitrogen and Rice. International Rice Research Institute, Los Banos, Philippines.

  8. Bottomley, W. B. 1920. The effect of organic matter on the growth of various water plants in culture solution. Ann. Bot.34: 353–365.

  9. Carrapico, F. 1991. Are bacteria the third partner of theAzolla-Anabaena symbiosis? Pl. & Soil137: 157–160.

  10. Cary, P. R. &P. G. J. Weerts. 1992. Growth and nutrient composition ofAzolla pinnata R. Brown andAzolla filiculoides Lamarck as affected by water temperature, nitrogen and phosphorus supply, light intensity and pH. Aquatic Bot.43: 163–180.

  11. Caudales, R., J. M. Wells, A. D. Antoine &J. E. Butterfield. 1995. Fatty acid composition of symbiotic cyanobacteria from different host plant (Azolla) species: Evidence for coevolution of host and symbiont. Intl. J. Syst. Bacteriol.45: 364–370.

  12. Chung-Chu, L. 1984. Recent advances onAzolla research. Pages 45–54in W. S. Silver & E. C. Schroder (eds.), Practical application ofAzolla for rice production. Martinus Nijhoff/W. Junk, Dordrecht.

  13. Cunningham, W. P. &B. W. Saigo. 1990. Environmental science: A global concern. Wm. C. Brown, Dubuque, Iowa.

  14. Das, D., K. Sikdar &A. K. Chetterjee. 1994. Potential ofAzolla pinnata as biogas generator and as a fish-feed. Indian J. Environna. Health36: 186–191.

  15. De Waha Baillonville, T., H. F. Diara, I. Watanabe, P. Berthet &C. Van Hove. 1991. Assessment and attempt to explain the high performance ofAzolla in subdesertic tropics versus humid tropics. Pl. & Soil137: 145–150.

  16. El-Sayed, A. F. M. 1992. Effects of substituting fish meal withAzolla pinnata in practical diets for fingerling and adult Nile tilapia,Oreochromis niloticus (L.). Aquac. & Fish. Managern.23: 167–173.

  17. Fogg, G. E., W. D. P. Stewart, P. Fay &A. E. Walsby. 1973. The blue-green algae. Academic Press, London.

  18. Forni, C., S. Gentili, C. Van Hove &M. Grilli-Caiola. 1990. Isolation and characterization of the bacteria living in the sporocarps ofAzolla filiculoides Lam. Ann. Microbiol. Enzimol.40: 235–244.

  19. Fremy, P. 1930. Les myxophycees de l’Afrique equatoriale francaise. Arch. Bot.3: 373–395.

  20. Hall, D. O., S. A. Markov, Y. Watanabe &K. K. Rao. 1995. The potential applications of cyanobacterial photosynthesis for clean technologies. Photosyn. Res.46: 159–167.

  21. Hamdi, Y. A. 1982. Application of nitrogen-fixing systems in soil improvement and management. FAO Soils Bull. 49. Food and Agriculture Organization, Rome.

  22. Hardy, R. W. F., R. D. Holsten, E. K. Jackson &R. C. Burns. 1968. The acetylene-ethylene assay for N2 fixation: Laboratory and field evaluation. PI. Physiol.43: 1185–1207.

  23. Hechler, W. D. &J. O. Dawson. 1995. Factors affecting nitrogen fixation inAzolla caroliniana. Trans. Illinois State Acad. Sci.88: 97–107.

  24. Hill, D. J. 1975. The pattern of development ofAnabaena in theAzolla-Anabaena symbiosis. Planta122: 179–184.

  25. —. 1977. The role ofAnabaena in theAzolla-Anabaena symbiosis. New Phytol.78: 611–616.

  26. Hur, J. S. &A. R. Wellburn. 1993. Effects of atmospheric sulfur dioxide onAzolla andAnabaena symbiosis. Physiol. Pl. (Copenhagen)88: 65–72.

  27. ——. 1994a. Effects of atmospheric O3 onAzolla-Anabaena symbiosis. Ann. Bot.73: 205–209.

  28. ——. 1994b. Effects of atmospheric NO2 onAzolla-Anabaena symbiosis. Ann. Bot.73: 137–141.

  29. Ismail, B. S., T. C. Sew &I. Mushrifah. 1995. Effect of molinate and carbofuran on nitrogen fixation byAzolla pinnata. Microbios82: 127–134.

  30. Ito, O. &I. Watanabe. 1985. Availability to rice plants of nitrogen fixed byAzolla. Soil Sci. Pl. Nutr.31: 91–104.

  31. Jain, S. K., P. Vasudevan &N. K. Jha. 1989. Removal of some heavy metals from polluted water by aquatic plants: Studies on duckweed and water velvet. Biol. Wastes28: 115–126.

  32. Johnson, G. V., P. A. Mayeux &H. J. Evans. 1966. A cobalt requirement for symbiotic growth ofAzolla filiculoides in the absence of combined nitrogen. PL Physiol.41: 852–855.

  33. Joy, P. P. &G. V. Havanagi. 1990. Studies on the integrated use of fertilizer nitrogen, phosphorus and azolla biofertilizer for rice. Mysore J. Agric. Sci.22: 436–443.

  34. Kannaiyan, S. 1993. Nitrogen contribution byAzolla to rice crop. Proc. Indian Natl. Sci. Acad., B59: 309–314.

  35. Kolhe, S. S. &B. N. Mittra. 1990.Azolla as an organic source of nitrogen in a rice-wheat cropping system. Trop. Agric. (Trinidad)67: 267–269.

  36. Kondo, M., M. Kobayashi &E. Takahashi. 1989. Effect of phosphorus onAzolla and its utilization in rice culture in Niger. PL & Soil120: 165–170.

  37. Krock, T., J. Alkamper &I. Watanabe. 1991. Azolla’s contribution to weed control in rice cultivation. PL Res. Developm.34: 117–125.

  38. Kushari, D. P. 1991. Multiplication of azolla associated with rice. Intl. Rice Res. Newslett.16: 18–19.

  39. — &I. Watanabe. 1992. Differential responses ofAzolla to phosphorus deficiency. II. Screening method under concentration controlled conditions. Soil Sci. Pl. Nutr.38: 65–73.

  40. Laurinavichene, T. V., A. F. Yakunin &I. N. Gogotov. 1990. Effect of temperature and photoperiod duration on growth and nitrogen fixation inAzolla. Fiziol. Rast. (Moscow)37: 457–461.

  41. Lay, W. L., S. N. Huang & C. T. Wang. 1989. Effects ofAzolla application on growth and yield of rice. Bull. Taichung Distr. Agric. Improvem. Sta., No.24: 3–12.

  42. Liu, C. C., W. D. Wei &D. Y. Zheng. 1984. Some advances inAzolla research. Page 57in C. Veeder & W. E. Newton (eds.), Advances in nitrogen fixation research. Martinus Nijhoff, The Hague.

  43. Lu, S. Y. 1987. Methods for usingAzolla filiculoides sporocarps to culture sporophytes in the field. Pages 27–32in International Rice Research Institute,Azolla utilization: Proceedings of the Workshop onAzolla Use. International Rice Research Institute, Los Banos, Philippines.

  44. Lumpkin, T. A. 1987a. Collection, maintenance, and cultivation ofAzolla. Pages 55–94in G. H. Elan (ed.), Symbiotic nitrogen fixation technology. Marcel Dekker, New York.

  45. —. 1987b. Environmental requirements for successfulAzolla growth. Pages 89–97in International Rice Research Institute,Azolla utilization: Proceedings of the Workshop onAzolla Use. International Rice Research Institute, Los Banos, Philippines.

  46. — &D. L. Plucknett. 1980.Azolla; Botany, physiology and use as a green manure. Econ. Bot.34: 111–153.

  47. ——. 1982.Azolla as a green manure: Use and management in crop production. Westview Press, Boulder, Colorado.

  48. Madhusoodanan, P. V. &P. J. Sevichan. 1992.Azolla microphylla Kaulfuss: An economically important biofertilizer for paddy fields of Kerala. J. Econ. Taxon. Bot.16: 73–76.

  49. Mahapatra, B. S. &G. L. Sharma. 1989. Integrated management ofSesbania, Azolla and urea nitrogen in lowland rice under a rice-wheat cropping system. J. Agric. Sci. (Cambridge)113: 203–206.

  50. Malavolta, E., W. R. Acorsi, A. P. Ruschel, F. J. Krug, L. I. Nakayama &I. Eimori. 1981. Mineral nutrition and N2-fixation inAzolla. Pages 205–211in P. B. Vose & A. P. Ruschel (eds.), Associative N2-fixation. Vol. 2. CRC Press, Boca Raton, Florida.

  51. Marwaha, T. S., B. V. Singh &S. K. Goyal. 1992. Effect of incorporation ofAzolla on wheat (Triticum aestivum var HD-2329). Acta Bot. Indica20: 218–220.

  52. Mian, M. H. &A. K. M. Azmal. 1989. The response ofAzolla pinnata R. Brown to the split application of phosphorus and the transfer of assimilated phosphorus to flooded rice plants. PI. & Soil119: 211–216.

  53. Misra, S. &B. D. Kaushik. 1989a. Growth promoting substances of cyanobacteria: I. Vitamins and their influence on rice plants. Proc. Indian Natl. Sci. Acad.,B 55: 295–300.

  54. —. 1989b. Growth promoting substances of cyanobacteria: II. Detections of amino acids, sugars and auxins. Proc. Indian Natl. Sci. Acad.,B 55: 499–504.

  55. Mochida, O. 1991. Spread of freshwaterPomacea snails (Pilidae, Mollusca) from Argentina to Asia. Micronesica3: 51–62.

  56. Moore, A. W. 1969.Azolla: Biology and agronomic significance. Bot. Rev. (Lancaster)37: 17–34.

  57. Mshigeni, K. E. 1982. Freshwater algal resources of Tanzania: A review and a discussion on their potential for agriculture, food production and other uses. Pages 175–201in H. A. Hoppe & T. Levring (eds.), Algae in pharmaceutical science. De Gruyter, Berlin.

  58. Murayama, N. 1979. The importance of nitrogen for rice production. Pages 5–23in International Rice Research Institute, Nitrogen and rice. International Rice Research Institute, Los Banos, Philippines.

  59. National Academy of Sciences. 1979. Microbial processes: Promising technologies for developing countries. Report of anad hoc panel of the Advisory Committee on Technology Innovation, Board on Science and Technology for International Development, Commission on International Relations. National Academy of Sciences, Washington, DC.

  60. Newton, J. W. 1976. Photoproduction of molecular hydrogen by a plant-algal symbiotic system. Science191: 559–561.

  61. Nickell, L. G. 1958. Physiological studies withAzolla under aseptic conditions. I. Isolation and preliminary growth studies. Amer. Fern J.48: 103–108.

  62. Nik-Khan, A. &M. Motaghi-Talab. 1992. The use ofAzolla in lactating cows. Iranian J. Agric. Sci.23: 47–56.

  63. Pablico, P. P. &K. Moody. 1991. Effect of fentin acetate on wet-seeded rice,Pistia stratiotes andAzolla pinnata. Crop Protect.10: 45–47.

  64. Park, I. H., K. K. Rao &D. O. Hall. 1991. Photoproduction of hydrogen, hydrogen peroxide and ammonia using immobilized cyanobacteria. Intl. J. Hydrogen Energy16: 313–318.

  65. Pasternak, P. S., V. G. Mazepa &G. K. Pristupa. 1988. The resistance of tree and shrub species to industrial emissions in the Poles’e region of the Ukraine. Lesnoe-Khozyaistvo7: 54–57.

  66. Peoples, M. B., D. F. Herridge &J. K. Ladha. 1995. Biological nitrogen fixation: An efficient source of nitrogen for sustainable agricultural production? Pl. & Soil174: 3–28.

  67. Peters, G. A. 1975. TheAzolla-Anabaena azollae relationship III. Studies on metabolic capacities and a further characterization of the symbiont. Arch. Microbiol.103: 113–122.

  68. —. 1976. Studies on theAzolla-Anabaena azollae symbiosis. Pages 592–610in W. E. Newton & C. J. Nyman (ed.), Proceedings of the First International Symposium on Nitrogen Fixation. Vol. 2. Washington State University Press, Pullman.

  69. —. 1977. TheAzolla-Anabaena azollae symbiosis. Pages 231–258in A. Hollaender (ed.), Genetic engineering for nitrogen fixation. Plenum Press, New York.

  70. —. 1978. Blue-green algae and algal associations. BioScience28: 580–585.

  71. — &B. C. Mayne. 1974a. TheAzolla-Anabaena azollae relationship. I. Initial characterization of the association. PL Physiol.53: 813–819.

  72. ——. 1974b. TheAzolla-Anabaena azollae relationship. II. Localization of nitrogen fixing activity as assayed by acetylene reduction. PL Physiol.53: 820–824.

  73. — &S. K. Perkins. 1993. TheAtolla andAnabaena symbiosis: Endophyte continuity in theAzolla life cycle is facilitated by epidermal trichomes: II. Re-establishment of the symbiosis following gametogenesis and embryogenesis. New Phytol.123: 65–75.

  74. Rains, D. W. &S. N. Talley. 1979. Use ofAtolla in North America. Pages 419–431in International Rice Research Institute: Nitrogen and rice. International Rice Research Institute, Los Banos, Philippines.

  75. Rajendran, R. &R. Reuben. 1988. Laboratory evaluation of the water fern,Azolla pinnata for mosquito control. J. Biol. Control2: 114–116.

  76. ——. 1991. Evaluation of the water fernAzolla microphylla for mosquito population management in the rice-land agro-ecosystem of south India. Med. Vet. Entomol.5: 299–310.

  77. Ram, H., P. Krishna Raja &M. V. S. Naidu. 1994. Effect ofAzolla on soil properties and yield of mungbean (Vigna radiata L.). J. Indian Soc. Soil Sci.42: 385–387.

  78. Robins, R. J., D. O. Hall, D. J. Shi, R. J. Turner &M. J. C. Rhodes. 1986. Mucilage acts to adhere cyanobacteria and cultured plant cells to biological and inert surfaces. FEMS Microbiol. Lett.34: 155–160.

  79. Rosenani, A. B. &H. A. Chilian. 1992. Availability of nitrogen from nitrogen-15 labeledAzolla pinnata and urea to flooded rice. Pl. & Soil143: 153–161.

  80. Satapathy, K. B. 1993. Effect of different plant spacing pattern on the growth ofAzolla and rice. Indian J. PL Physiol.36: 98–102.

  81. Saunders, R. M. K. &K. Fowler. 1992. A morphological taxonomic revision ofAzolla Lam. sectionRhizosperma (Mey.) Mett. (Azollaceae). Bot. J. Linn. Soc.109: 329–357.

  82. ——. 1993. The supraspecific taxonomy and evolution of the fern genusAzolla (Azollaceae). PL Syst. Evol.184: 175–193.

  83. Saxena, D. K. 1995. Purification efficiency ofLemna andAzolla for WIMCO effluent. Proc. Natl. Acad. Sci. India,B 65: 61–65.

  84. Sculthorpe, C. D. 1967. The biology of aquatic vascular plants. Edward Arnold, London.

  85. Shi, D. J. &D. O. Hall. 1988. TheAzolla-Anabaena association: Historical perspective, symbiosis and energy metabolism. Bot. Rev. (Lancaster)54: 353–386.

  86. Silvester, W. B. 1977. Dinitrogen fixation by plant associations excluding legumes. Page 141in R.W. F. Hardy & A. H. Gibson (eds.), A treatise on dinitrogen fixation: Section IV, agronomy and ecology. Wiley-Inter Science, New York.

  87. Singh, A. L. &P. K. Singh. 1990a. Intercropping ofAzolla biofertilizer with rice at different crop geometry. Trop. Agric. (Trinidad)67: 350–354.

  88. ——. 1990b. Phosphorus fertilization and the growth and nitrogen fixation ofAzolla and blue-green algae in rice field. Indian J. Pl. Physiol.33: 21–26.

  89. Singh, D. P. &P. K. Singh. 1995. Response ofAzolla caroliniana and rice to phosphorus enrichment of theAzolla inoculum and phosphorus fertilization during intercropping. Exp. Agric.31: 21–26.

  90. Singh, P. K., D. P. Singh &R. P. Singh. 1992. Growth, acetylene reduction activity, nitrate uptake and nitrate reductase activity ofAzolla caroliniana andAzolla pinnata at varying nitrate levels. Biochem. Physiol. Pflanzen.188: 121–127.

  91. Singh, R. P. &P. K. Singh. 1988. Symbiotic algal nitrogenase activity and heterocyst frequency in sevenAzolla species after phosphorus fertilization. Hydrobiologia169: 131–318.

  92. ——. 1989. Effect of nitrogen fertilizers on nitrogen fixation and heterocyst frequency of cyanobacteriumAnabaena azollae in 7 species ofAzolla. Biochem. Physiol. Pflanzen.185: 429–433.

  93. Singh, S., R. Prasad, S. K. Goyal, B. V. Singh, T. S. Marwaha &S. N. Shanna. 1992. Effect ofAzolla, blue-green algae and fertilizer nitrogen on wetland rice (Oryza sativa). Indian J. Agron.37: 569–571.

  94. Sisworo, E. L., D. L. Eskew, W. H. Sisworo, H. Rasjid, H. Kadarusman, S. Solahuddin &G. Soepardi. 1990. Studies on the availability ofAzolla nitrogen and urea nitrogen for rice growth using nitrogen-15. Pl. & Soil128: 209–220.

  95. Stumpe, J. M. &P. L. G. Vlek. 1991. Acidification induced by different nitrogen sources in columns of selected tropical soils. Soil Sci. Soc. Amer. J.55: 145–151.

  96. Sutton, S. D., G. W. Barrett &D. H. Taylor. 1991. Microbial metabolic activities in soils of old-field communities following eleven years of nutrient enrichment. Environna. Pollut.73: 1–10.

  97. Tan, B. C., P. Payawal, I. Watanabe, N. Lacdan &C. Ramirez. 1986. Modern taxonomy ofAzolla: A review. Philipp. Agric.69: 491–512.

  98. Teckle-Haimanot, E. V. D. 1995. Comparison ofAzolla mexicana and N and P fertilization on paddy taro (Colocasia esculenta) yield. Trop. Agric. (Trinidad)72: 70–72.

  99. Thangaraju, M. &S. Kannaiyan. 1993. Effect of nitrogen fixing water fernAzolla and different forms of urea application on the growth, nitrogen uptake and grain yield of rice crop. Acta Agron. Hung.42: 69–76.

  100. Tuan, D. T. &R. Q. Thuyet. 1979. Use ofAzolla in rice production in Vietnam. Pages 395–405in International Rice Research Institute, Nitrogen and rice. International Rice Research Institute, Los Banos, Philippines.

  101. Tung, H. F. &R. C. Shen. 1985. Studies of theAzolla pinnata-Anabaena azollae symbiosis: Concurrent growth ofAzolla with rice. Aquatic Bot.22: 145–152.

  102. Vaishampayan, A., Y. R. Reddy, B. D. Singh &R. M. Singh. 1992. Reduced phosphorus requirement of a mutantAzolla-Anabaena symbiotic N2-fixing complex. J. Exp. Bot.43: 851–856.

  103. Van Cat, D., I. Watanabe, W. J. Zimmerman, T. A. Lumpkin &T. De Waha Baillonville. 1989. Sexual hybridization amongAzolla species. Canad. J. Bot.67: 3482–3485.

  104. Van Hove, C. 1989.Azolla and its multiple uses with emphasis on Africa. Food and Agriculture Organization, Rome.

  105. Venkataraman, G. S. &B. D. Kaushik. 1980. Save on N fertilizers by the use of algae on rice fields. Indian Farm.30: 27–30.

  106. Ventura, W. &I. Watanabe. 1993. Green manure production ofAzolla microphylla andSesbania rostrata and their long-term effects on rice yields and soil fertility. Biol. Fertil. Soils15: 241–248.

  107. —— &G. B. Mascarina. 1992. Mineralization ofAzolla nitrogen and its availability to wetland rice: II. Fertilizer effect and nitrogen-15 uptake by rice from different species ofAzolla with varying nitrogen contents. Soil Sci. Pl. Nutr.38: 505–516.

  108. Wagner, G. M. 1983. The ecology and nitrogen-fixing capacity of freshwater blue-green algae in selected localities in Tanzania. M. Sc. thesis, University of Dar es Salaam.

  109. —. 1988. The role of freshwater blue-green algae in biological nitrogen fixation in selected localities in Tanzania. Pages 29–33in J. R. Mainoya (ed.), Proceedings of the Symposium on Two Decades of Science Development in Tanzania, 1965–1985, Dar es Salaam, Tanzania, 2–6 September 1985. University of Dar es Salaam and Tanzania National Scientific Research Council, Dar es Salaam.

  110. -. 1992. Algae in agriculture with special emphasis on their application in rice production. Pages 359–373in K. E. Mshigeni, J. Bolton, A. Critchley & G. Kiangi (eds.), Proceedings of the First International Workshop on Sustainable Seaweed Resource Development in Sub-Saharan Africa, Windhoek, Namibia, 22–29 March 1992.

  111. -. 1996. TheUtricularia-Cyanophyta andAzolla-Anabaena associations: Their ecology, nitrogen fixation rates, and effects as biofertilizers on rice. Ph.D. thesis, University of Dar es Salaam.

  112. Wang, S. M., Q. L. Wang, S. H. Li &J. R. Zhang. 1991. A study of treatment of spring wheat with growth promoting substances from nitrogen-fixing blue-green algae. Acta Hydrobiol. Sinica15: 45–52.

  113. Watanabe, I. 1982.Azolla-Anabaena symbiosis—Its physiology and use in tropical agriculture. Pages 169–185in Y. R. Dommergues & H. G. Diem (eds.), Microbiology of tropical soils and plant productivity. Martinus Nijhoff/W. Junk, The Hague.

  114. —. 1984. Use of symbiotic and free-living blue-green algae in rice culture. Outlook Agric.13: 166–172.

  115. —. 1985. Limiting factors in increasing N2-fixation in rice fields. Pages 436–453in H. Ssali & S. O. Keya (eds.), Biological nitrogen fixation in Africa: Proceedings of the First Conference of the African Association for Nitrogen Fixation. The Nairobi Rhizobium Microbiological Resources Centre, Nairobi.

  116. — &C. C. Liu. 1992. Improving nitrogen-fixing systems and integrating them into sustainable rice farming. PL & Soil141: 57–67.

  117. — &C. M. Ramirez. 1984. Relationship between soil phosphorus availability andAzolla growth. Soil Sc. Pl. Nutr.30: 595–598.

  118. — &W. Ventura. 1992. Long-term effects of azolla and sesbania on rice yield and fertility of tropical wetland rice soil. Pages 331–342in Proceedings of the International Symposium on Paddy Soils, Nanjing, China, 15–19 September 1992. Academia Sinica, Beijing, China.

  119. —,N. S. Berja &D. C. Del Rosario. 1980. Growth ofAzolla in paddy field as affected by phosphorus fertilizer. Soil Sci. Pl. Nutr.26: 301–307.

  120. —,C. R. Espinas, N. S. Berja &B. V. Alimagno. 1977. Utilization of theAzolla-Anabaena complex as a nitrogen fertilizer for rice. Intl. Rice Res. Inst. Res. Pap. Ser.11: 1–15.

  121. —,T. Lapis, R. Oliveros &W. Ventura. 1988. Improvement of phosphate fertilizer application toAzolla. Soil Sci. Pl. Nutr.34: 557–569.

  122. Yatazawa, M., N. Tomomatsu, N. Hosoda &K. Nunome. 1980. Nitrogen fixation inAzolla-Anabaena symbiosis as affected by mineral nutrient status. Soil Sci. Pl. Nutr.26: 415–426.

Download references

Author information

Correspondence to Gregory M. Wagner.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Wagner, G.M. Azolla: A review of its biology and utilization. Bot. Rev 63, 1–26 (1997) doi:10.1007/BF02857915

Download citation

Keywords

  • Nitrogen Fixation
  • Botanical Review
  • Rice Field
  • Biological Nitrogen Fixation
  • International Rice Research Institute