The effect of sodium hydrogen carbonate treatment on the growth and organic nutrient composition of Azolla

Abstract

Azolla experiments were conducted in May 2019 at Makerere University Botanical Garden, Kampala Uganda. The effect of varying concentrations of sodium hydrogen carbonate on the growth and organic nutrient composition was analyzed. The Azolla was grown under homogeneous conditions with the only variation being in the concentration of sodium hydrogen carbonate. The experiments were terminated after 5 days and the Azolla analyzed. There was an increase in phytomass across the four setups however the more increase was observed in the negative control which went on decreasing as the concentration was increased. The same effect was observed for the organic nutrient composition as total carbohydrate, total crude protein and ether extract reduced with increase in sodium hydrogen carbonate concentration. This was accrued to the effect of high pH that was outside the optimum range on the biochemical processes of the Azolla which had a negative effect on growth and photosynthesis. Therefore I concluded that increase in concentrations of sodium hydrogen carbonate led to a decrease in the phytomass accumulation and organic nutrient composition of the Azolla. It was recommended that a buffer should be added to the growth media if sodium hydrogen carbonate is to be used as an inorganic carbon source for Azolla to neutralise the effect on pH. It was further recommended that alternative sources of inorganic carbon with less impact on pH should be used. And lastly the light intensity at which the Azolla is grown should be increased to increase its tolerance to high pH.