~ Azolla, Anabaa and Organic Farming 

Azolla - Azolla is a small group of freshwater floating ferns that belongs to the genus Salviniales, a popular indoor aquatic plant.  There are about seven species of Azolla ferns worldwide, including A. microphylla, A. imbricate and A. caroliniana.  Each of these fern species has the following common features.  That is;  Short, branched floating stalk and curved leaves divided into two segments, upper and lower.  The lower part is thin and is always slightly submerged, giving the plant buoyancy.  The upper part is green or purple and has a hollow inside.  These holes are the places that make for a very special symbiotic relationship. 

Anabaena azollae Cyanobacteria live in these cavities.  Cyanobacteria are commonly referred to as blue-green algae due to their external morphological similarity.  However, Algae - algae is a separate genus of bacterial organisms that includes a wide variety of species, including green algae, red algae, and diatoms, and is a bacterial genus.  It can be said that virtually all true algae evolved from these cyanobacteria, or blue-green algae.  Cyanobacteria, true algae, and plant cells all have the same pigments that contribute to photosynthesis.  No single bacterial species has developed single-celled cells.  However, other species of cyanobacteria, including Anabaena cyanobacteria, carry the precursors of tissue evolution, forming a collection of cells that line up in a single line, forming a triad of three functional cell types in one such collective unit.  They are;

1. Vegetative cells - contain photosynthetic pigments and new cells are formed by cell division.

2. Heterocysts - cells involved in nitrogen (N2) fixation.

3. Akinetes - These are strong, closed, spore cells made by the cyanobacteria to protect the cyanobacteria in an environment that is detrimental to the cyanobacteria.

Of these, heterozygous cells are the major factor in the symbiotic association between Azolla fern and Anabina cyanobacteria.  Although nitrogen is an essential element from the enzymes of every living thing to the formation of DNA molecules, it is a very stable and relatively small molecule that makes it possible for nitrogen biofluorescence to take up 78% of the atmospheric gaseous molecules in n2 molecules.  Plant species meet their nitrogen requirements through nitrogen-containing ions such as NO3- and NO2- dissolved in soil water or water, and all animals depend directly or indirectly on those plants.  Therefore, fluctuations in the amount of nitrogen ions dissolved in soil water or water in an environment affect the plants and animals that inhabit it.  Although mammals are of this type, some microbial species use a more efficient series of chemical reactions to directly convert atmospheric N2 molecules into NH4 +, or ammonia molecules, for their nitrogen needs.  This is called biological nitrogen fixation.  As mentioned above, this is a stable nitrogen supply mechanism due to its high atmospheric N2 percentage.

Many species of bacteria undergo similar or similar nitrogen fixation, and this is also the case with heterosis of anabina cyanobacteria.  Anabina species, when deficient in the aforementioned nitrogen ions in the surrounding environment, make up between 7% -20% of their cell group to the extent of heterosis.  These heterozygous cells, which are large and have minimal amounts of photosynthetic pigments, are some of the adaptations designed for nitrogen fixation in cells.

Heterosis is the conversion of atmospheric N2 (g) -> NH4 + (aq) or ammonium ions.  An enzyme called nitrogenase produces the activation energy needed to carry out this reaction inside the cell.  The enzyme nitrogenase is activated in an anaerobic environment without oxygen (O2).  Therefore, in heterosis, there are four cell walls that prevent oxygen gas from entering.  There are residual oxygen-consuming proteins inside the cell, and photosystem II, a chlorophyll structure that decomposes to photosynthesis, is decomposed.  But heterosis has the structure of photosystem I, which produces the energy needed to screen nitrogen.  There are channels between the cells that receive heterocyst-related nutrients through the growth cells as carbohydrates (sucrose sugars) and only to deliver the NH4 + growth cells that are screened by the heterocysts, and there are cyanophycin (cyanophycin) cells that reduce molecular diffusion between cells to prevent the entry of oxygen.  So this is a factory with amazing natural environmental control.

Excess cyanobacteria excrete 30% -50% of the ammonium ions produced by the cell in heterosis.  This is a huge excess in terms of the size of the heterosis in a complete anabina.  Millions of years of natural selection and evolution have produced several plant species that have adapted to absorb this excess ammonium.  Seven species of Azolla ferns are the chief among them.  Excess ammonium released by anabina cyanobacteria, which adapt to live collectively in the cavity of the upper lobe of the azolla leaves, is a stable source of nitrogen for the azolla plant.  In cyanobacteria, heterosis is usually caused by nitrogen ion fluctuations, but heterosis occurs in response to symbiotic plant emissions.  Therefore, the nitrogen source of Azolla is another stand.  Although photosynthesis also occurs in cyanobacteria, the carbohydrates required for the anabolic cyanobacteria that coexist in the azolla leaves are obtained from the carbohydrates produced by the photosynthesis of the azolla plant.  Therefore, there is a very well-divided labor between Azolla fern and Anabina cyanobacteria.

This link between Azolla and Anabina is not limited to these two species.  About 5% of the excess ammonium released by anabina is released into the surrounding environment, which is beneficial to any other plant living in that aquatic environment.  Utilizing this process for paddy cultivation, which grows under the same environmental conditions as azolla, is therefore very effective.  Even the 25 * C temperature at which azolla grows successfully is quite comparable to the aquatic temperature of paddy fields in Sri Lanka.  In addition, research has shown that azolla does not restrict crop growth, but inhibits the growth of common weeds in the field.  The rapid growth rate of Azolla fern, high nitrogen fixation capacity and rapid decomposition are all three factors that are very beneficial for paddy cultivation.  Mineralization provides 5% of the screened ammonium that is immediately added to the paddy field, as well as the remaining 95% of the nitrogen from the azolla plants that decompose quickly into the liquid soil.  There are many farms across Asia that have used this method for paddy cultivation and have achieved higher yields than non-cyanobacterial farms.  Therefore, it can be said that the use of azolla bio-fertilizer in paddy cultivation according to proper control methods will be a successful step towards the present fertilizer crisis to some extent.