Optimal growth conditions of Azolla pinnata R. Brown: impacts of light intensity, nitrogen addition, pH control, and humidity

Dataset for a journal article published on Plants 2022, vol. 11, no. 1048.

Nitrogen pollution from agriculture, a major challenge facing our society  today. Biological nitrogen fixation is key to combat damages caused by synthetic nitrogen. The Azolla spp. species are  ideal  candidates  for  fast  nitrogen fixation.  This  study  aims  to  investigate  the  optimal growth conditions  of  Azolla  pinnata  R.  Brown.  The growth  conditions  investigated  were  the  growth  medium type and strength, light intensity, nitrogen presence/absence in the medium, pH control, and humidity.  Higher  light intensities  increased  plants  growth  by,  on  average,  32 %. The highest  humidity (90 %) yielded higher growth rate values  than the lower humidity values (60 % and 75 %). The presence of nitrogen in the medium had no significant effect on the growth rate  of the plants. pH control was critical under fast growth conditions of high light intensity and high humidity, and this  reduced  algal  growth  (from visual  observation).  The  optimal  growth  rate  achieved was 0.321 day-1, a doubling time of 2.16 days. This was achieved by using a 15 % strength of Hoagland’s medium, high light intensity (20 000 lx), nitrogen present, and pH control at 90 % humidity. These optimised  conditions  offer an  improvement  to  existing  Azolla  pinnata-phytoremediation  systems and aids in the fight against synthetic nitrogen pollution.