Adaptation of Azolla Mycrophyla to Brackish Water Ecosystem

Abstract

Abstract Azolla microphylla is a tropical and subtropical fern with a length of 1.5-2.5 cm. Some genera can grow in brackish waters, but these biota are more commonly referred to as freshwater plants. Utilization of this macrophyte as fish and livestock feed (cattle, goats, ducks, ducks and chickens) have been introduced in some part of the world. Therefore, it is necessary to know the best way to adapt the fern into brackish water ecosystem and examine the potential for growth in such environment. In this study, two adaptation methods were performed, namely instant adaptation (IA) method and the step by step adaptation (SSA) method. A number of 25-liter plastic basin were filled with 20 l of freshwater or sea water, salt marsh sediment (500 g) and fermented chicken manure (500 g) and used as experimental unit. In the IA approach, the water salinity was adjusted from the beginning at 0, 5, 10, 15 and 20 ppt, planted with fern and observed for 21 days. While in the SSA method, the fern was firstly grown on an experimental unit of 0 ppt for 7 days. Then the water salinity was increased of 1 ppt every 7 days, until day 49. All experimental units were observed daily, including; survival rate, absolute growth, total growth, doubling time, and histological observations of leaves, rhizomes and macrophyte roots. The study showed that in IA aproach, A. microphyla grew normally only in salinity 0 ppt (freshwater). In 5 ppt experimental unit, the organisms survived until day 14. Similarly, at 10 ppt, the macrophytes grew and branched up to day 7. While the treatment of salinity 15 and 20 ppt A. microphylla survived up to 5 and 3 days only, respectively. In SSA method, the fern grew well and the population increased until day 49 at salinity 6 ppt. From the study can be suggested that in case of growing A. mycrphylla in brackish water ecosystem, the organism can be cultivated at salinity below 6 ppt by using step by step method of adaptation.