Developing birdsfoot trefoil (Lotus corniculatus L.) varieties for permanent pasture applications in low latitude regions of eastern Australia

Abstract

Birdsfoot trefoil (Lotus corniculatus L.) is a potentially important alternative legume for recharge landscapes in the high rainfall zone in eastern Australia. However, in the summer rainfall region in northern New South Wales (NSW) where birdsfoot trefoil has the greatest potential application, flowering and seed set are limited by short daylength. Consequently, existing birdsfoot trefoil cultivars do not set enough seed to develop a seedbank that sustains a productive persistent stand. A breeding program was undertaken to develop birdsfoot trefoil cultivars adapted to short photoperiod to increase the area sown to deep-rooted perennials in the grazing lands in eastern Australia. Three new birdsfoot trefoil experimental varieties, Phoenix, Venture and Matador, were developed through: (1) phenotypic selection within cv. Grasslands Goldie for flowering intensity and pod set, (2) phenotypic selection for these same traits in a broader sample of 49 world-sourced lines, and (3) selection for prostrate growth habit among progeny of pair-crosses between erect and prostrate accessions identified as productive in southern NSW. Following two cycles of selection for flowering prolificacy and pod set, the average number of umbels per stem in the Goldie-derived populations was five times greater than in the commercial Goldie population; this response to selection closely approximated the predicted response based on previous estimates of heritability and phenotypic variance for this trait. In comparison with Goldie, the Syn1 and Syn2 populations of the three experimental varieties consistently expressed earlier flowering maturity and higher seed yield potential in glasshouse and field trials in northern NSW. While germination rate and seedling vigour of the three experimental varieties was slightly less than Goldie, intensive selection pressure on reproductive traits did not compromise seasonal herbage production.