Physiological Behavior of the Aquatic Plant Azolla sp. in Response to Organic and Inorganic Fertilizers

Abstract

The present investigation aims to evaluate the impacts of organic and inorganic fertilizers on the water parameters and physiological behaviors of an aquatic plant (Azolla sp.). The experiment used three groups: treatment with organic or inorganic fertilizer and a group with no fertilization as a control. Azolla sp. were grown in cement ponds that received different treatments. For water analysis, the obtained results clarified that fertilization resulted in no variation in the temperature or total hardness among different treatments. Organic fertilizer increased the dissolved phosphorus content, total hardness, and bicarbonate alkalinity, as well as the total phosphorus content, whereas inorganic treatment increased the pH, total ammonia content, and total nitrogen content. Regarding the biochemical composition of Azolla sp., the chlorophyll content showed no variation among different treatment groups, while organic matter showed high variation among different treatment groups. The highest values for ash and fat content were recorded in control ponds. The highest protein content was found in organic treatment ponds. The addition of fertilizers led to an increase in the tissue contents of N and P compared to the control. This increase was highest when Azolla sp. was fertilized with organic fertilizer. The atomic N:P ratio was low in tissues subjected to either treatment compared with the control. The doubling time of Azolla sp. was decreased by fertilization. It is concluded that different fertilizer systems have significant effect on physico-chemical and biological parameters of water. Fertilization positively affects Azolla sp. growth. Organic fertilizer was more efficient for the growth of Azolla sp., so it can be considered as a source of biofertilizer and green manure in areas where it spreads.