Fig. 4.

(A) Example exponential fits of root dry mass allocation with depth for two mature Kenia plants under standard nutrient supply (filled circles; y=0.0271e^–0.0338x, R²=0.949) and reduced nutrient supply (open circles; y=0.0043e^–0.0406x, R²=0.835). (B) Genotypic variation in coefficient ‘b’ of the fitted exponential curve. Values are the mean (±SE) of ln-transformed data, and least significant difference (LSD) bars and letter annotations indicate where differences are significant at the 5% level. (C) Regression of mean nitrogen uptake efficiency on mean root size coefficient ‘a’ of the fitted exponential curve for genotypes grown under standard (filled symbols) and reduced (50% standard; open symbols) nutrient supply, assessed at stem extension (circles), anthesis (triangles), and maturity (squares).