COMPARISON OF SOIL- AND NUTRIENT-BASED MEDIUM FOR MAINTENANCE OF AZOLLA CULTURES

Soil- and nutrient medium-based cultures of Azolla were compared in terms of growth, nitrogen (N) fixation and chlorophyll content. Soil-based cultures show similar growth in terms of fresh weight, as media-based cultures. Acetylene reduction activity and chlorophyll content were found to be very high in soil-based cultures. Studies on soil N, phosphorus (P), potassium (K), and carbon (C) contents reveal that N and K contents in soil increase after inoculation of Azolla plants in soil-based cultures, while P content of soil decreases. In Azolla plants available N, P, and K contents were high in nutrient media-based cultures, initially, but N and P content of soil-based cultures kept for long period (>2 months) were significantly higher than media-based cultures. Nutrient media-based cultures require an early transferring in to fresh media as compared to soil-based cultures. The results indicate that soil-based cultures of Azolla are as good as nutrient media-based cultures of Azolla.