Biotechnology and Bioinformatics (1+1)

6.3.2. Potentials of Azolla

Though Azolla is capable of absorbing nitrogen from its environment, Anabaena meets the entire nitrogen requirements of Azolla–Anabaena association.

• The mean daily nitrogen fixing rates of a developed Azolla mat are in the range of 1.0–2.6 kg/ha and a comparison with the process of industrial production of nitrogenous fertilizers would indicate the efficacy of biological nitrogen fixation.
• While the latter carried out by the enzyme nitrogenase, operates with maximum efficacy at 30^ºC and 0.1 atm, Haber-Bosch process employed by the fertilizer industry requires reaction of nitrogen and hydrogen to form ammonia at a temperature and pressure as high as 300ºC and 200 – 1000 atm respectively.

The normal doubling time of Azolla plants is three days and one kg of phosphorus applied results in 4-5 kg of nitrogen, through Azolla, i.e. about 1.5 – 2.0 t of fresh biomass.

• Azolla can survive in a wide pH range of 3.5 to 10.0 with an optimum of 4.5–7.0
• withstand salinities of up to 10 ppt.
• With a dry weight range of 4.8–7.1% among different species, the nitrogen and carbon contents are in the ranges of 1.96–5.30% and 41.5–45.3% respectively.

Added to these are its high rates of decomposition with mean daily loss rates of 1.36–4.57% of the initial weight and nitrogen release rates of 1.25% which make Azolla a potential biofertilizer in aquaculture systems.

Azolla is considered as a multifaceted and multipurpose bio-resource. It can be used as:

• green manure specially for rice;
• mosquito-controlling agent;
• Water purifier-capable of absorbing the nutrients from the eutrophic waters;
• poultry and duck feed; fish feed
• source of nitrogen;
• Antifungal agent
• natural biofertiliser; and
• source of hydrogen gas