Using a rhizosheath selection tool to screen perennial ryegrass for root hair traits that reduce root competition against white clover

This study tested whether selection of perennial ryegrass for reduced root hair length and density would reduce root competition on white clover for phosphate (P) with no detrimental effect on ryegrass growth. A Rhizosheath Selection Tool was used to select two ryegrass populations with contrasting root hair traits. The two ryegrass populations were grown at five soil P levels in a glasshouse experiment and rhizosheath trait selection had no detrimental effect on growth or shoot P concentrations. The two ryegrass populations were also grown with companion white clover in soils with Olsen P 12 or 19 mg L-1 with partitions separating the shoot systems to prevent shoot competition. In the Olsen P 12 soil, clover grown with the low rhizosheath sized ryegrass had significantly heavier shoots and contained more P than clover grown with the high rhizosheath ryegrass. In the Olsen P 19 soil differences in ryegrass rhizosheath had no effect on clover growth. The results showed that under the experimental conditions, grass-clover competition for soil P could be modified by the rhizosheath traits of ryegrass.