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INTRODUCTION 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 AS COMPONENT OF INM 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
CHARACTERISTICS OF BLUE GREEN ALGAE 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
Treatment Grain yield (q/ha) 2000 2001 2002 Control 34.27 39.64 45.61 40 kg N/ha 46.50 42.58 50.73 80 kg N/ha 50.67 45.84 53.80 120 kg N/ha 53.10 47.84 55.30 BGA 43.70 40.17 48.60 BGA + 40 kg N/ha 51.57 48.04 52.70 BGA + 80 kg N/ha 54.70 51.06 55.80 BGA + 120 kg N/ha - 51.42 56.70 ALGALIZATION EFFECT ON PADDY BGA SUPPLEMENT NITROGEN IN ACHIEVING YIELD EQUIVALENT TO MINERAL NITROGEN ALONE
BLUE GREEN ALGAE Fix atmospheric nitrogen Contribute 25- 30 kg N /ha /season BLUE GREEN ALGAE Increase rice yield by 10-15 % Secrete Vitamins & hormones
MASS PRODUCTION OF BGA CULTURE 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
MASS PRODUCTION OF BGA CULTURE Thick algal mat forms at 15 days Allow water to evaporate Collect dry algal flakes Make into powder and pack in polybags
LET US SUM UP 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. contd…
contd… 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.
ASSESSMENT 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 % contd…
contd… 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
ASSESSMENT Model Answers : i) Anabaena ii) 10-15 percent iii) 10-15 % iv) Fix nitrogen gas into ammonia and nitrate v) Ammonia
REFERENCES 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