1. 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 10 kg/ha one week after rice transplantation contribute kg N /ha /season with a yield enhancement of percent. Besides fixing nitrogen, these algae excrete vitamins and hormones, which may also contribute to the growth of rice plants.

2. 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

3. 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 10 kg/ha one week after rice transplantation contribute kg N /ha /season with a yield increase of percent. Blue green algae excrete vitamins and hormones, which  enhance rice growth. BGA also enhances soil fertility

4. 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

5. Some blue Green Algal Species

6. ALGALIZATION EFFECT ON PADDY
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 kg N/ha -
51.42
56.70
BGA SUPPLEMENT NITROGEN IN ACHIEVING YIELD EQUIVALENT TO MINERAL NITROGEN ALONE

7. Fix atmospheric nitrogen Contribute 25- 30 kg N /ha /season
BLUE GREEN ALGAE
Fix atmospheric nitrogen
BLUE GREEN ALGAE
Contribute kg N /ha /season
Increase rice yield by
10-15 %
Secrete
Vitamins & hormones

8. 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

9. 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

10. 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…

11. contd…
BGA 10 kg/ha one week after rice transplantation contribute kg N /ha /season with a yield enhancement of percent.
Indian rice fields also harvours different BGA species – Anabaena, Nosto, Cylindrospermum, Westolliopsis, etc.

12. 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) % c) %
b) 1-5 % d) 50 %
contd…

13. 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

14. ASSESSMENT Model Answers : i) Anabaena ii) 10-15 percent iii) 10-15 %
iv) Fix nitrogen gas into ammonia and nitrate 
v) Ammonia

15. REFERENCES i) Soil Microbiology – N. S.Subba Rao
ii) Advances in Microbiology – N. S.Subba Rao
iii) Bio-fertilizer and Organic Farming – NIIR Board
iv) Nitrogen fixing organisms
(Pure and applied aspects) – J. I. Sprent and P. Sprent