Growth of Temperate Perennial Legumes over Three Cycles of Defoliation at Different Temperatures

Summer-active legumes such as big trefoil (Lollis ped11nc11lat11s), birdsfool trefoil (Lot11s comic11la111s), crownvelch (Coronilla varia) and cicer milkvetch (Astraga/11s cicer) are needed for summer rainfall areas of the perennial pasture zone in eastern Australia where soil conditions and grazing management do not suit lucerne (Medicago sativa). The growth of these species was compared at 4 temperatures regimens (14/10, 18/14, 22/18, 26/22°C, 12:12 h) for 3 cycles of regrowth where soil moisture was serially changed from field capacity (FC) to 50% PC and back to PC in a growth cabinet pot experiment. Growth rates in lucerne always exceeded those of the other legumes, but the differe��ce was very marked at the two lowest temperature regimens. The rhizome-forming crownvetch and cicer milkvetch had fewer and much shorter above-ground stems than the other species, and leaf appearance rates were reduced at successive regrowth cycles in cicer milkvetch. Soil moisture stress was not severe enough to significantly reduce legume growth except at 26/22°C. Selection for better growth at mo· derate temperatures between 15 and 20°C could improve the potential usefulness of crownvetch. and cicer milkvetch.