Comparative efficacy of Azolla in combination with certain organic manures for production of zooplankton

Abstract

The study has been carried out to investigate the effect of Azolla in combination of certain organic manures (OM) for production of live fish food organisms. Experiment was carried out with nine treatments by mixing single super phosphate (0.7 g) with different doses of OM/Azolla/OM+Azolla viz. T1(control) – only single super phosphate (SSP), T2 – Cow dung, T3 – cow dung + Azolla, T4 – Azolla (100%), T5 – Azolla (50%), T6 – poultry manure, T7- poultry manure + Azolla, T8 – vermicompost, T9 – vermicompost + Azolla. The effect of manuring on water quality parameters has also been studied. The maximum average zooplankton population (805 Nos/l); and maximum zooplankton biomass (36.86 g/250L) were observed in T7 i.e. Azolla and poultry manure. The trend of best organic manure based on the zooplankton productivity (population and biomass) in descending order as observed in the present study is – Poultry manure + Azolla (T7) > poultry manure (T6) > cow dung + Azolla (T3) > vermicompost + Azolla (T9) > vermicompost (T8) > cowdung (T2) > Azolla (100%) (T4) > Azolla (50%) (T5) > Single super phosphate SSP control (T1). The trend of dominance of zooplankton categories observed by per cent contribution in all treatment was- Nauplii (35.63%) > Cladocerans (24.98%) > Copepods (21.01%) > Rotifers (18.47 %). The study concludes that Azolla in combination of organic manures particularly with poultry manure proposition is most suitable for mass production of live fish food organisms. It is followed by cowdung and vermicompost in combination of Azolla.