Defoliation and moisture stress influence competition between endophyte-free tall fescue and white clover, birdsfoot trefoil and Caucasian clover

Abstract

TOsceola white clover, AU Dewey birdsfoot trefoil, Rhizo Caucasian clover and Triumph tall fescue were grown in 2:1 and 1:2 grass legume mixtures, and in monocultures of each species, and defoliated at intervals of 3 and 6 weeks, with unrestricted watering, and two cycles of water stress in a glasshouse pot trial. Competition from tall fescue had a greater effect on legume performance than the cutting or moisture stress treatments. Caucasian clover was more severely affected by competition from tall fescue than either ladino clover or birdsfoot trefoil. Roots of Caucasian clover did not branch and spread amongst the root mass of tall fescue in the same manner as ladino clover. The legumes always exhibited lower leaf water potentials under moisture stress than did tall fescue, and ladino clover made up a greater proportion of the mixtures under 3-week cutting and adequate moisture. We concluded that while ladino clover and birdsfoot trefoil ombined well with tall fescue, the establishment and vigour of Caucasian clover could be very sensitive to the sowing density of companion grass species, particularly on shallow soils with restricted rooting depth.