Abstract
Messina (Melilotus siculus) cv. Neptune, an annual pasture legume native to the Mediterranean Basin, has recently been released for saltland pastures in southern Australia following demonstration of biomass production and persistence superior to other commercial pasture legumes in saline environments prone to winter waterlogging. Self-regenerating annual pasture legumes also require seed adaptations for both tolerating and avoiding salinity at germination in these environments. This study examined diversity within Neptune and 20 other messina accessions for salt tolerance at germination, recovery of germinability from temporary salt stress, and timing and extent of hardseed softening, compared with balansa clover (Trifolium michelianum) cv. Frontier, burr medic (Medicago polymorpha) cv. Scimitar and white melilot (Melilotus albus) cv. Jota. Germination rates after 14 days at 300 mM NaCl relative to 0 mM NaCl were ≥99% for Neptune and 18 other messina accessions, 66% for Scimitar, 21% for Jota and 11% for Frontier. No genotype germinated at 600 mM NaCl; however, when transferred to 0 mM NaCl after 14 days at 600 mM, all genotypes except Scimitar and Jota recovered partial germination, ranging from 13% to 93% of controls (0 mM NaCl for 28 days). The softening rate of hard (impermeable) seeds in the field varied among genotypes, with deferral of hardseed softening until late autumn–early winter, when rainfall is more likely, indicating greater persistence. The months in which the hardseed level first became significantly lower than the initial level (in freshly harvested seeds) after placement on the soil surface in December were: March for Frontier; April for Scimitar, Jota and Neptune; and March–July for all messina accessions. This study confirmed that messina has high salt tolerance and several avoidance mechanisms at germination that contribute to its adaptation to saline soils in southern Australia. Several messina accessions were superior to Neptune for individual traits which could be exploited for plant breeding. These results also have implications for saltland pastures in other regions of the world with Mediterranean-type climates.
Highlights
Dryland salinity is a major threat to the productivity of Australian agriculture (Rogers et al 2005; Bennett et al 2009)
Many saline soils are prone to winter waterlogging in southern Australia (McFarlane and Williamson 2002), with the salt tolerance of most plants severely compromised under waterlogged conditions (Barrett-Lennard and Shabala 2013)
This paper examines diversity within Neptune and 20 other messina accessions for germination and seedling traits important for adaptation to saline soils, compared with cultivars of balansa clover, burr medic and white melilot
Summary
Dryland salinity is a major threat to the productivity of Australian agriculture (Rogers et al 2005; Bennett et al 2009). Mediterranean-type climates, such as occur in much of southern Australia, are characterised by dry hot summers and cool winters during which up to 65% of the annual rainfall is received, and a growing season of 4–9 months (Porqueddu et al 2016) In these environments, the development and commercial release of salt-tolerant plant species adapted to saline environments is crucial to ensure the sustainability of Journal compilation Ó CSIRO 2021 Open Access CC BY agricultural productivity (Howieson et al 2000; Rogers et al 2005; Hughes et al 2008). Many saline soils are prone to winter waterlogging in southern Australia (McFarlane and Williamson 2002), with the salt tolerance of most plants severely compromised under waterlogged conditions (Barrett-Lennard and Shabala 2013) This represents a significant limitation to the productivity of saltland pastures
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
