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Cyanobacteria ( BGA) can be found in almost every conceivable environment. Blue green algae are photosynthetic Cyanobacteria and promote the growth of lowland paddy by supplying fixed nitrogen through exudation.BGA application @ 10 kg/ha one week after rice transplantation contribute 25 - 30 kg N /ha /season with a yield enhancement of 10-15 percent. Besides fixing nitrogen, these algae excrete vitamins and hormones, which may also contribute to the growth of rice plants.
Blue green algae found in almost every environment, from oceans to fresh water to bare rock to soil. They occur as plantonic cells or form phototrophic biofilm in marine environments, in damp soil, moistened rocks ,deserts
Blue green algae are photosynthetic Cyanobacteria ,promote the growth of lowland paddy by supplying nitrogen. In Indian soils-Anabaena, Nostoc, Aulosira, Cylindrospermum, Gleotrichia, Calothrix, Scytonema, Tolypothrix, Fischerella and Westiollopsis are dominant.BGA application @ 10 kg/ha one week after rice transplantation contribute 25 - 30 kg N /ha /season with a yield increase of 10-15 percent. Blue green algae excrete vitamins and hormones, which enhance rice growth. BGA also enhances soil fertility
Cyanobacteria include unicellular and colonial form.
Colonies form filaments, sheets , hollow balls.
Filaments differentiate into vegetative cells,
heterocysts and resistant spores
Heterocyst is the site of nitrogen fixation
Heterocyst fix nitrogen into ammonia and nitrate Nitrate and ammonia absorbed by plants
Grain yield (q/ha)
40 kg N/ha
80 kg N/ha
120 kg N/ha
BGA + 40 kg N/ha
BGA + 80 kg N/ha
BGA + 120 kg N/ha
ALGALIZATION EFFECT ON PADDY
BGA SUPPLEMENT NITROGEN IN ACHIEVING YIELD EQUIVALENT TO MINERAL NITROGEN ALONE
Fix atmospheric nitrogen
Contribute 25- 30 kg N /ha /season
BLUE GREEN ALGAE
Increase rice yield by
Vitamins & hormones
Shallow trays (2m x 1m) of galvanized sheet
Spread 8-10 kg soil plus 200 g SSP
Add water (5-15cm)
Sprinkle algal culture
Expose to sunlight
Thick algal mat forms at 15 days
Allow water to evaporate
Collect dry algal flakes
Make into powder and pack in polybags
Blue green algae are photosynthetic Cyanobacteria which form phototrophic biofilm in fresh water and marine environments, in damp soil, or even on temporarily moistened rocks in deserts.
Promote the growth of lowland paddy by supplying fixed nitrogen through exudation.
Blue green algae also excrete vitamins and hormones, which may also contribute to the growth of rice plants.
BGA application @ 10 kg/ha one week after rice transplantation contribute 25 - 30 kg N /ha /season with a yield enhancement of 10-15 percent.
Indian rice fields also harvours different BGA species – Anabaena, Nosto, Cylindrospermum, Westolliopsis, etc.
Q. Choose the correct answer :
i) The most commonly found Cyanobacterial species in Indian rice soil.
a) Anabaena c) Azotobacter
b)Rhizobium d) Azospirillum
ii) How much rice yield can be increased by application of BGA?
a) 10-15 % c) 15-20 %
b) 1-5 % d) 50 %
iii) What is the function of Heterocysts?
a) fix nitrogen gas into c) produce vitamins
ammonia and nitrate
b) produce hormones d) phosphate solubilization
iv) Which form of nitrogen is taken up by rice plant?
a) Ammonia c) Nitrate
b) Nitrite d) Nitrogen
Model Answers :
ii) 10-15 percent
iii) 10-15 %
iv) Fix nitrogen gas into ammonia and nitrate
i) Soil Microbiology – N. S.SubbaRao
ii) Advances in Microbiology – N. S.SubbaRao
iii) Bio-fertilizer and Organic Farming – NIIR Board
iv) Nitrogen fixing organisms
(Pure and applied aspects) – J. I. Sprent and P. Sprent