Root architectural responses of wheat cultivars to localised phosphorus application are phenotypically similar

Differences in nutrient recovery from fertiliser bands may improve cereal variety selection. The objective of this study was to identify the variation in root plasticity across commonly grown Australian wheat (Triticum aestivum L.) cultivars in response to a phosphorus (P)-enriched band. Ten wheat cultivars were screened for root proliferation within a 150 mg P kg-1 band in P-responsive soil. Plants were destructively harvested at the four-leaf phenological stage and various growth parameters, including root length density (RLD), were measured on banded and uniformly adequate P treatments. All wheat cultivars increased RLD between three and nine times in the P band. However, there was no significant difference in root plasticity among the cultivars tested. Although all cultivars produced longer, though ~ 9% thinner roots when responding to the P band, the phenotypic response was unable to compensate fully for the lower P status encountered in the soil. Despite 23% longer root lengths in the P-band treatments, P uptake per unit root length was 78% lower than in uniformly adequate P treatments. Our results indicate that root plasticity of wheat cultivars in a P-enriched band was phenotypically similar. Further research is necessary before selecting for wheat cultivars that respond to localised nutrient patches with increased RLD.