DEFOLIATION AND MOISTURE STRESS INFLUENCE COMPETITION BETWEEN ENDOPHYTE-FREE TALL FESCUE AND WHITE CLOVER, BIRDSFOOT-TREFOIL AND CAUCASIAN CLOVER

Osceola white clover, AU Dewey birdsfoot trefoil, Rhizo Caucasian clov er and Triumph tall fescue were grown in 2: 1 and 1:2 grass legume mix tures, and in monocultures of each species, and defoliated at interval s of 3 and 6 weeks, with unrestricted watering, and two cycles of wate r stress in a glasshouse pot trial. Competition from tall fescue had a greater effect on legume performance than the cutting or moisture str ess treatments. Caucasian clover was more severely affected by competi tion from tall fescue than either ladino clover or birdsfoot trefoil. Roots of Caucasian clover did not branch and spread amongst the root m ass of tall fescue in the same manner as ladino clover. The legumes al ways 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 tha t while ladino clover and birdsfoot trefoil ombined well with tall fes cue, the establishment and vigour of Caucasian clover could be very se nsitive to the sowing density of companion grass species, particularly on shallow soils with restricted rooting depth.