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

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

CHARACTERISTICS OF BLUE GREEN ALGAE

Some blue Green Algal Species

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 + 120 kg N/ha - 51.42 56.70

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 10-15 %

SecreteVitamins & hormones

BLUE GREEN ALGAE

MASS PRODUCTION OF BGA CULTUREMASS PRODUCTION OF BGA CULTURE

Shallow trays (2m x Shallow trays (2m x 1m) of galvanized 1m) of galvanized sheetsheet

Spread 8-10 kg soil Spread 8-10 kg soil plus 200 g SSPplus 200 g SSP

Shallow trays (2m x Shallow trays (2m x 1m) of galvanized 1m) of galvanized sheetsheet

Spread 8-10 kg soil Spread 8-10 kg soil plus 200 g SSPplus 200 g SSP

Add water (5-15cm)Add water (5-15cm)

Sprinkle algal culture Sprinkle algal culture

Expose to sunlightExpose to sunlight

Add water (5-15cm)Add water (5-15cm)

Sprinkle algal culture Sprinkle algal culture

Expose to sunlightExpose to sunlight

MASS PRODUCTION OF BGA CULTUREMASS PRODUCTION OF BGA CULTURE

Thick algal mat forms Thick algal mat forms at 15 daysat 15 days  Allow water to Allow water to evaporateevaporate

Thick algal mat forms Thick algal mat forms at 15 daysat 15 days  Allow water to Allow water to evaporateevaporate

Collect dry algal Collect dry algal flakes flakes   Make into powder and Make into powder and pack in polybags pack in polybags

Collect dry algal Collect dry algal flakes flakes   Make into powder and Make into powder and pack in polybags 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.

ASSESSMENTQ. 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.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