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Azolla: A review of its biology and utilization

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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.

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  1. Department of Zoology and Marine Biology, University of Dar es Salaam, P.O. Box 35064, Dar es Salaam, Tanzania

    Gregory M. Wagner

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

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