Abstract:
Azolla pinnata R.Br. is an aquatic fern that grows on the surface of water bodies. The unique
quality of A. pinnata is its symbiotic relationship with a prokaryotic cyanobacterium (Anabaena
azollae), which confers a high rate of nitrogen fixation. It is important to find the growing
conditions of Azolla in different water sources for its optimum biomass production for different
usages such as biofertilizers, animal feeds, water purification and biofuel production. This
preliminary study was conducted to investigate the effect of water sources on the growth
performance (shoot biomass, root biomass, root length), and the chlorophyll content of Azolla.
Presence of Anabaena in Azolla fronds was monitored by light microscope and number of filaments
were counted per leaflet. The experiment utilized three types of water sources (tap water as control
(T1), lake water (T2) and cattle manure mixed tap water (T3), in plastic buckets with 40 cm in
diameter and 25 cm in height. Each treatment was triplicated in a completely randomized design
and total biomass was collected weekly. Data were statistically analyzed using Minitab 17. The
highest biomass of Azolla was obtained in T3 from the first week until 8th week and it was higher
from T1 and T2. The highest chlorophyll content was obtained in T3 (6.4 SPAD value) showed a
significant difference from T1 and T2 (p<0.05). The dry weight of roots and root length in T1
showed a significant difference from T2 and T3 (p<0.05). The highest root length was observed as
5 cm in T1 indicating that roots may be in search of nutrients and the lowest root length was
observed as 0.8 cm in T3 with high nutrient concentrations in water. The highest number of
Anabaena was observed in the leaflet of Azolla fronds in T3 which in turn increase N content in
Azolla plants. It reveals that application of cattle manure in tap water significantly affects the plant
biomass and the chlorophyll content of Azolla. Further studies are needed to conduct in large scale
growing facilities with different nutrient concentrations of water sources to find sustainable and
optimum growing conditions for Azolla and the nutrient concentrations of the plants.
