This paper reviews the major issues that impact upon the development of improved fodder species for saline environments across temperate Australia. It describes past and present research that has been, or is being, undertaken towards improvements in salt tolerance in forage species within Australia in relation to the principal regions where salinity occurs. It includes a discussion on the mechanisms of salt tolerance in plants. An extensive list of known or potential salt-tolerant fodder species is provided and the key opportunities for advancement within each of the 4 major forage groups: grasses, legumes, herbs and shrubs are discussed. Constraints to developing new salt and waterlogging tolerant fodder species are identified. A number of recommendations are made for research that should ensure that Australian producers have access to a new array of productive fodder species suited to saline environments.
Thirty perennial grass accessions were evaluated for emergence, growth and persistence at 6 severely salinised seepage scalds on the western slopes of New South Wales. Warm-season accessions were sown or planted in spring 1996 and 1997, and cool-season types in autumn 1996 and 1997. Control species, tall wheat grass (Thinopyrum ponticum) and puccinellia (Puccinellia ciliata) were sown in spring and autumn. Plants were monitored over 2 growing seasons. None of the accessions, including the controls, performed well at all sites. Of the accessions established from seed, tall wheat grass was the most reliable in terms of the number of successful establishments but its growth potential was only achieved at a few sites. Some warm-season species (Panicum coloratum, Chloris gayana and Cynodon dactylon) approached their growth potential at some sites but overall rates of establishment were very low. The performance of puccinellia appeared to be adversely affected by low pH. It was concluded that on severely scalded sites, vegetative propagation of stoloniferous–rhizomatous plants, e.g. Pennisetum clandestinum, Paspalum vaginatum and C. gayana, may be the best option.
Emergence and survival of Thinopyrum ponticum cv. Dundas, Puccinellia ciliata cv. Meneman, and Trifolium fragiferum cv. Palestine were observed over three seasons (2004–06) on part of a salinised area in Central Western New South Wales. Grid sampling of topsoils in August 2003 indicated that the site was acidic (mean pHwater 6.05), sodic (exchangeable sodium percentage 29), and saline (estimated ECe 18 dS/m). The site comprised a mosaic of low-salinity (ECe ~6 dS/m) vegetated patches and high-salinity (ECe ~30 dS/m) bare patches where EC was highly variable seasonally (exceeding 100 dS/m) and spatially. Despite suboptimal rainfall, emergence of the grasses was satisfactory on bare patches in all seasons but T. fragiferum failed to emerge in 2004 and was omitted from subsequent sowings. Various methods of ‘engineering’ the bare patches, viz. ditching, mounding, straw mulching, liming, or hand weeding, failed to promote optimum growth of the grasses, although survival was generally enhanced in treatments that included a shallow ditch. Results of the experiments, and observations elsewhere on the salinised area (where some patches supported optimal performance of the three species), suggested that high salinity was the main reason for poor performance on the bare patches. It was concluded that comprehensive site definition, both spatial and temporal, is important before attempting revegetation. Nevertheless the response of T. ponticum and P. ciliata in ditches will be limited on high-salinity sites. In addition, it was observed that surface disturbance and reduced grazing promoted establishment and growth of pre-existing species, particularly Cynodon dactylon and Lolium rigidum. There are many salinised sites in the Central West of NSW where neither P. ciliata nor T. ponticum has performed well, nor would be expected to do so, and where management of native and naturalised species already present may provide the best option for enhancing ground cover and herbage production.
Perennial ‘couch’ grasses that reproduce from rhizomes and or stolons have some advantages on scalded saline sites where they can reproduce in situations that are often hostile to germination and establishment of obligate seeders. Promising couch grass species from an earlier evaluation at Wagga Wagga and Manildra were Cynodon dactylon, Paspalum vaginatum, Sporobolus virginicus and, to a lesser extent, Sporobolus mitchellii. This paper reports results of a subsequent evaluation of these species as well as Eragrostis dielsii and Distichlis distichophylla at 3 other saline sites (Burrumbuttock, Cudal and Cundumbul). All accessions were established vegetatively and assessed for vigour and survival (all sites), groundcover production and its relationship with EC and pH (2 sites), biomass production, forage value and the effect of regular cutting on groundcover (1 site). S. virginicus appeared the most tolerant to saline conditions and produced high levels of groundcover and biomass but was sensitive to regular defoliation. At the 2 alkaline sites, C. dactylon and D. distichophylla generally outperformed the other accessions in terms of persistence and groundcover but appeared to be relatively low in forage value, and D. distichophylla appeared to have significant weed potential. Paspalum vaginatum produced high groundcover and relatively high biomass of moderate forage value at Burrumbuttock but performed poorly at the other sites. S. mitchellii and E. dielsii persisted on the more benign sites producing only low amounts of dry matter and groundcover and may be useful for environmental plantings where low weed potential is paramount. Despite spatially intensive testing of the topsoil chemistry, there were no obvious relationships between EC or pH and plant performance at the 2 main trial sites – a possible consequence of vegetative propagation.
Two scalded saline sites on the inland slopes of NSW were selected for an evaluation of ten accessions of warm-season stoloniferous/rhizomatous grass species: common couch (Cynodon dactylon), marine couch (Sporobolus virginicus), rats-tail couch (S. mitchellii), salt-water couch (Paspalum vaginatum), water couch (P. distichum) and one exotic, kikuyu (Pennisetum clandestinum). Most species performed well at Wagga Wagga but only common couch, marine couch and salt-water couch did at Manildra, where they consistently outperformed the other native species in terms of survival, groundcover and vigour. Salt-water couch had the highest mean vegetative cover at both sites. Differences in salinity, pH (acid cf. alkaline) and particularly topsoil moisture probably accounted for differing plant performances at the two sites. In a follow-up production study of the most successful accessions under relatively dry conditions at Manildra, the 'Yamba' accession of marine couch consistently produced more leaf/seedhead dry matter (1057 ± 172 kg/ha) during the growing season than the others. However, salt-water couch consistently produced more ex-plot stolon/rhizome dry matter (974 ± 127 kg/ha) than the other two species. This probably explained its ability, unlike marine couch, to maintain groundcover during a regime of regular cutting. Further evaluation under grazing and recreational uses is recommended. The genetic material evaluated was only a small sample of salt-tolerant native grasses. The variable performance of the four accessions of rats-tail couch, for example, suggested that more salt-tolerant types are likely to be found.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.