Figure 2.

The ability of 21 day old maize genotypes to retain biomass when grown at 0.5 mM nitrate with respect to growth at 2.5 mM nitrate. Values are the predicted values of shoot biomass of plants grown at 0.5 mM ${\text{NO}}_3^{-}$ as a percentage of the predicted shoot biomass at 2.5 mM ${\text{NO}}_3^{-}$. Filled bars represent lines that are significantly smaller in the low N treatment at 0.05 significance level.