Australian farmers and scientists have embraced the use of new pasture legume species more than those in any other country, with 36 annual and 11 perennial legumes having cultivars registered for use. Lucerne (Medicago sativa), white clover (Trifolium repens), and red clover (T. pratense) were introduced by the early European settlers and are still important species in Australia, but several other species, notably annual legumes, have been developed specifically for Australian environments, leading to the evolution of unique farming systems. Subterranean clover (T. subterraneum) and annual medics (Medicago spp.) have been the most successful species, while a suite of new annual legumes, including serradellas (Ornithopus compressus and O. sativus), biserrula (Biserrula pelecinus) and other Trifolium and Medicago species, has expanded the range of legume options. Strawberry clover (T. fragiferum) was the first non-traditional, perennial legume commercialised in Australia. Other new perennial legumes have recently been developed to overcome the soil acidity and waterlogging productivity constraints of lucerne and white clover and to reduce groundwater recharge and the spread of dryland salinity. These include birdsfoot trefoil (Lotus corniculatus), Talish clover (T. tumens), and hairy canary clover (Dorycnium hirsutum). Stoloniferous red clover cultivars and sulla (Hedysarum coronarium) cultivars adapted to southern Australia have also been released, along with a new cultivar of Caucasian clover (T. ambiguum) aimed at overcoming seed production issues of cultivars released in the 1970s. New species under development include the annual legume messina (Melilotus siculus) and the perennial legume narrowleaf lotus (L. tenuis) for saline, waterlogged soils, and the drought-tolerant perennial legume tedera (Bituminaria bituminosa var. albomarginata). Traits required in future pasture legumes include greater resilience to declining rainfall and more variable seasons, higher tolerance of soil acidity, higher phosphorous utilisation efficiency, lower potential to produce methane emissions in grazing ruminants, better integration into weed management strategies on mixed farms, and resistance to new pest and disease threats. Future opportunities include supplying new fodder markets and potential pharmaceutical and health uses for humans and livestock. New species could be considered in the future to overcome constraints of existing species, but their commercial success will depend upon perceived need, size of the seed market, ease of establishment, and management and safety of grazing animals and the environment. Molecular biology has a range of potential applications in pasture legume breeding, including marker-assisted and genomics-assisted selection and the identification of quantitative trait loci and candidate genes for important traits. Genetically modified pasture plants are unlikely to be commercialised until public concerns are allayed. Private seed companies are likely to play an increasingly important role in pasture legume development, particularly of mainstream species, but the higher risk and more innovative breakthroughs are likely to come from the public sector, provided the skills base for plant breeding and associated disciplines is maintained.

https://bioone.org/journals/Crop-and-Pasture-Science/volume-63/issue-9/CP12194/Temperate-pasture-legumes-in-Australiatheir-history-current-use-and-future/10.1071/CP12194.pdf

Temperate pasture legumes in Australia—their history, current use, and future prospects

Salinity and waterlogging as constraints to saltland pasture production: A review

The relationship of root porosity and radial oxygen loss on arsenic tolerance and uptake in rice grains and straw.

Halophytes as forages in saline landscapes: Interactions between plant genotype and environment change their feeding value to ruminants

The effects of radial oxygen loss on arsenic tolerance and uptake in rice and on its rhizosphere

Identifying forage species that are productive in saline environments is an important research priority in many areas of the world affected by salinity. The salt and waterlogging tolerances of 19 species of Melilotus were evaluated in a series of glasshouse experiments. Measurements taken on each species included: dry matter (DM) production, root growth and development, shoot ion (Na+, K+ and Cl−) concentrations, root porosity, and in vitro estimates of nutritive value. Research on several species was restricted because of their potential as weed risks. Of the remaining species, M. siculus (syn. M. messanensis), an annual species, showed high relative salt and waterlogging tolerances, good DM production under non-stressed and stressed (saline and hypoxic) conditions, a high level of root porosity under stagnant conditions, low tissue ion (Na+, Cl−) concentrations, and a reasonable dry matter digestibility content (range 66–69%) under highly saline conditions. M. sulcatus ssp. segetalis and M. indicus were also identified as species with good DM production and tolerance to salinity and waterlogging stresses. Further weed risk assessments and field trials on these species are required before they can be promoted for use as pasture forages on saline areas.

/pdf/diversity-in-the-genus-melilotus-for-tolerance-to-salinity-3cs43r7gwn.pdf

A.D. Craig

Papers

Diversity in the genus Melilotus for tolerance to salinity and waterlogging