There was a highly significant genotype by rock phosphate by AM fungus interaction for % root mass (root fresh weight/total fresh weight × 100) ( P = 0.004) which was high in both cultivars in the absence of rock P (65–67%) but was lowest for Azucena with rock phosphate and AM fungus (61%) and lowest in Bala with rock phosphate but without AM fungus (58%).
Once variation due to position and neighbors was removed from the data by subtracting their estimated effect from the observations, a two way analysis of variance (factors; treatment and genotype) on the SDW of the controls and rock phosphate treatment demonstrated a weakly significant effect of the rock phosphate treatment ( P = 0.045) explaining less than 1% of the variation with rock phosphate stimulating growth (84.6 vs. 83.6 mg) and no cultivar by treatment interaction, while cultivar explained 68% of the non-spatial variation.