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Home >>Use Of Microbes in Industry and Agriculture >> Algal Fertilizers (BAG + Azolla)
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Algal Fertilizers (BAG + Azolla) - Bluge green algae (BGA) and Azolla constitute a system, which is the main source of algal biofertilizer in south and Southeast Asia, particularly for lowland paddy. BGA inoculation (without Awl/a) with composite cultures of algal genera Anabaena, Nostoc, Plectonema, Aulosira, Oscillatoria, Tolypothrix, etc. have been found to be more effective than single cultures.

Production and multiplication of BGA cultures is done at centres. Application of dried blue green algae flakes at the rate of 10 kg. /ha is recommended ten days after transplantation of rice.

Besides being a source of N2, BGA provides for the following other advantages:
(i) algal biomass accumulates as organic matter;
(ii) growth. promoting substances arc produced, which stimulate growth of rice seedling;
(iii) it provides partial tolerance to pesticides and fungicides;
(iv) it also helps in reclamation of saline and alkaline soils.
BGA is also supplied with Azolla (an aquatic fern), which harbours Anabaena azolle (a BGA) in leaf cavities, providing symbiotic association.

Azolla with Anabaena has been used with some success, but there are following limitations:
(i) Azolla, as a green manuring crop is labour intensive;
(ii) raising of Azolla needs assured and adequate supply of water;
(iii) damage of Azolla (in the nursery) is caused by pest diseases, heat, etc.
(iv) optimum temperature is required for Azolla multiplication.
Phosphate solubilising bacteria (PSB, e.g. Thiobacillus, Bacillus spp., etc.) and plant growth promoting rhizobacteria (PGPR), including Pseudomonas fluorescens and P. putida are important new biofertilizers. PSBs convert non-available inorganic phosphates into soluble organic phosphates, which can be utilized by crop plants.
PGPRs produce siderophores (iron chelating substances, e.g. pseudobactin), which chelate with iron and' make it unavailable to harmful fungi (e.g. Eriwinia) in rhizosphere, leading to their death; PGPRs have resulted in an increase in yields of potato (30%), radish (60-144%) and sugarbeet (4-8t/ha). These biofertilizers are yet to be commercially utilized in our country.

 
 

 
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