The effectiveness of nostoc as a biofertilizerfor rice crops in a rice fields?

Question

The effectiveness of nostoc as a biofertilizerfor rice crops in a rice fields?

Answer 1

Nostoc is an excellent biofertilizer for rice fields on account of its nitrogen fixing ability ( Due to its heterocysts ).

It is a natural fertilizers.

In some countries like India and other south east countries .

Nostoc is collected in dry season  in the form of mud balls and used in the rainy season to spread in the rice fields to enhance the nitrogen supply.

Besides being a natural fertilizer , It does no harm to the soil .

Chemical fertilizers are , on the other hand , damaging to the soil in the long run.

More details -

The lack of nitrogen in agriculture, and negative environmental effects of fertilizers, have stimulated interest in creating artificial associations between N2-fixing cyanobacteria  like NOSTOC  and rice (Oryza sativa). For the first time, numerous  Nostoc isolates from natural symbioses were screened for their ability to associate with rice.

Successful colonizers were tested for N2-fixation by acetylene reduction and for their ability to adsorb to roots by chlorophyll a measurements.

Paranodules were induced by 2,4-dichlorophenoxyacetic acid. And genetic fingerprints of the cyanobacteria like Nostoc were obtained for identification.

Ultrastructural investigations were made by light and scanning electron microscopy.

Twenty-one symbiotic Nostoc isolates associated with rice roots, colonizing surfaces and intercellular spaces. Adsorption was high and appeared biphasic.

The rates of N2 fixation by associated cyanobacteria( Nostoc  and its allies ) were higher compared with those in free-living cyanobacteria. Paranodules were formed and colonized, but root growth was adversely affected.

Under laboratory conditions, artificial associations were created between one-third of the screened symbiotic cyanobacteria and rice.

The agricultural potential for the association appears high since the cyanobacteria adsorb tightly and fix more N2 than when free-living.