Genotype x environment interactions for root depth of wheat

Improved wheat cultivars that incorporate traits for root penetration through compacted soil layers would enhance root acquisition of water and nutrients at depth. We report on findings from field trials aiming at understanding genotype x environment (G x E) interaction associated with differences in root penetration ability in wheat. G x E interactions for root depth were assessed for 24 wheat genotypes over six field environments in Western Australia. Environments were in the low rainfall zone with an average annual rainfall of around 320 mm. Soils either contained a hardpan of ~4 MPa at 0.2 m or gradually increased in soil strength with depth; all soils increased in hardness significantly with drying. For root depth, genotype accounted for only 12% of total variance compared with 40% for G × E interaction. Three environment and six genotype groups were identified. Genotypic differences in root growth between environments were related to a differential capacity to respond in penetration to changes in soil hardness and/or soil water content. Genotype groups were identified that were differentially adapted to alternative soil conditions and these were consistent with previous physiological analyses on representatives from those groups. In conclusion, genotypic variation in root traits was beneficial for growth under soil physical impedance and soil drying and supported the hypothesis of improved ability for penetration in hard soils or adaptation to drought. Associations with physiological and genetic evidence will be discussed. Sample Content Snapshot For root depth, genotype accounted for only 12% of total variance compared with 40% for G × E interaction. Differences in root growth between environments were related to a differential capacity to respond in penetration to changes in soil hardness and/or soil water content.