highly significantp < 0.01
The effects of pH (X 1 ), iron concentration (X 2 ), and ammonium nitrate concentration (X 3 ) on growth were highly significant ( p < 0.01).
The effects of pH (X 1 ), iron concentration (X 2 ), and ammonium nitrate concentration (X 3 ) on growth were highly significant ( p < 0.01).