Effect of defoliation frequency on growth and survival of four accessions of Psoralea eriantha

Abstract

Four accessions of the semi-arid shrub legume Psoralea eriantha were evaluated under three six and nine week cutting regimes for 72 weeks in pots in the glasshouse. Total yield increased in all accessions with increasing intervals between cutting. Yield in the three week cutting interval was only 36 per cent of the yield in the nine week cutting interval. The one erect accession, though giving the highest average yield, also suffered the highest mortality under the frequent defoliation. The other accessions suffered little mortality. Defoliation frequency affected root and stubble weights and these were closely correlated with total dry matter yields. Frequent defoliation also markedly reduced the number of primary and secondary shoots. It is suggested that survival under grazing may be more important than a higher yielding ability.