Differences in Root and Shoot Response to Limited N-supply in Oat and Spring Barley

Oat and spring barley cultivars, varying in origin and date of release, were examined in soil boxes with sloped glass-face. Considerable genotypic differences were found in shoot and root response to high and low nitrogen supply. Oat cultivars, representing a wider germplasm collection, exhibited a stronger and partially different shoot and root response to applied N-levels than barley cultivars. Cultivar-fertilization interaction effects were significant for seminal and adventitious root variation. Genotypic specificity (plasticity) in root response, as revealed in some oat and barley cultivars with a deeper penetration and more vigorous root growth under the low N-supply, was recognized to be a valuable adaptive characteristic for breeding plants on light-textured soils.