Elite selection of tagasaste (Chamaecytisus palmensis) for droughtprone sites

Abstract

Tagasaste (tree lucerne) is a drought-tolerant, shrub/ tree legume which is naturalised in many parts of New Zealand. It is a potentially useful supplementary forage for sheep and cattle, particularly in summer and early autumn. Tagasaste is highly variable for a range of attributes and in the 1980s, 16 lines were identified which had improved production, habit, and frost and disease tolerance. From 1993 to 1996, this germplasm was evaluated for morphological and chemical attributes at two sites in the lower North Island - Onga Onga, central Hawke's Bay (Trial 1) and Bulls, Rangitikei (Trial 2) - to select material for release. Differences in survival and growth of the lines between sites were the major finding. Average plant survival of lines in Trial 1 was higher than in Trial 2 (89 vs 58%), whereas growth of lines in Trial 2 exceeded that in Trial 1, for example for plant height (274 vs 168 cm), plant width (325 vs 168 cm), root collar diameter (91 vs 58 mm) and total plant dry matter (15.6 vs 6.7 kg/plant). The total N content of lines in Trial 2 was 25% higher than in Trial 1 (33 vs 26 g N/kg DM) whilst in vitro digestibility of herbage from all lines at each site was 75%. Two lines, AL2244 and AL2432, which had high survival at both sites, and means for other attributes which were similar to or exceeded the site mean for all lines, were selected to comprise the final release. Seed of these lines is being increased. Keywords: browse shrubs, Chamaecytisus palmensis, drought fodder, dryland legumes, revegetation, selection