Mj. Blumenthal et Rl. Ison, PLANT-POPULATION DYNAMICS IN SUBTERRANEAN CLOVER AND MUREX MEDIC SWARDS .2. PLANT-POPULATION DENSITY, Australian Journal of Agricultural Research, 45(4), 1994, pp. 929-944
It is possible that the use of harder-seeded varieties of sub. clover
(Trifolium subterraneum) and the recently domesticated murex medic (Me
dicago murex) may improve annual legume persistence in pasture leys. T
o determine the mechanisms of production and persistence in these two
species, plant population density changes in single seed (sprayed) and
naturally regenerating (unsprayed) swards were monitored in four vari
eties of sub. clover and two lines of murex medic over a three year pe
riod at Forbes in central-west N.S.W. Seedling recruitment was very se
nsitive to soil water and temperature at the time of germination and e
mergence, particularly in murex medic. Murex recruitment under irrigat
ion was at least four times greater than without irrigation on a germi
nable seed basis. Irrigation of sub. clover swards did not improve rec
ruitment to the same extent as it did in murex medic. Even the soft se
eded cultivars (Junee, Seaton Park and Woogenellup) can regenerate fro
m residual seed in the year following a year in which no seed was set,
although there are qualifications for Woogenellup. Plant population d
ensity (D) declined over the growing season, despite the specific effe
cts of environment and management; initial plant population density (D
(i)) appears to have the greatest influence on dry matter production o
ver the growing season.