False-colour scanning electron micrograph of the cyanobacteria (blue-green algae),Anabaena azollae grown here under experimental conditions. This Anabaena forms a symbiotic relationship with the water fern Azolla,whereby the rate of photosynthesis is doubled and the nitrogen requirements of the plant are fulfilled internally by the cyanobacteria. Both these factors give the water fern a competitive advantage over other water plants,a factor spotted by the Chinese 2000 years ago. The Anabaena-Azolla association is used as a green manure for rice crops. Anabaena is a filamentous organism,which,apart from vegetative cells,forms heterocysts and akinetes | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / PROFESSOR DAVID HALL |
Taille de l’image : | 4410 px × 4015 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |