The introduction of exotic pasture germplasm has formed the foundation of many Australian grazing systems. Scientists have searched the world for plants to improve the feedbase, amassing collections of diverse genetic material, creating genebanks that have made a large contribution to feedbase productivity. These genebanks contain a vast range of legumes, grasses, herbs and shrubs with growth habits ranging from small herbaceous plants to woody trees and life cycles from annuals to short- and long-term perennial plants. They have been collected from cool temperate to tropical climates and arid to high-rainfall zones. Hundreds of cultivars have been developed from material either collected by Australian plant breeders overseas or introduced from overseas genebanks. The collection of this germplasm has enabled plant breeders to extend the area of adaptation of species into climates, soils and systems previously considered marginal. The importance to Australian and world agriculture is increasing as plant breeders seek traits to meet the challenges of a changing climate and animal production systems. Furthermore, urbanisation, landscape degradation and political instability are making it increasingly difficult to collect pasture and forage germplasm from native grasslands in many countries. This emphasises the need to maintain and improve the capacity of the Australian Pastures Genebank (APG). The APG houses ∼85 000 accessions and is a modern, online source of diversity for plant scientists around the world. This paper summarises the history of the founding genebank collections, their environment and farming systems focus, and the visionary and resourceful individuals that built them.

Perennial pastures are the dominant feedbase in many regions of the world, and offer several advantages when compared with an annual pasture system. In Western Australia (WA) there has been a concerted effort over seven decades to develop new perennial pasture options and expand the adoption of suitable species. The agricultural region of WA (i.e. south-western Australia) is characterised by a Mediterranean climate where the 5–7 month summer drought has proved a considerable challenge with only a small number of the many promising species being adopted commercially. Research, development, and extension have covered a wide range of herbaceous perennial legumes, leguminous and native shrubs, herbs, and temperate and warm season grasses. This paper reviews the literature to determine whether a perennial pasture must satisfy the following criteria to be successful and widely adopted in south-western Australia: (i) sourced from a similar Mediterranean environment and adapted to the target soils; (ii) have a relative advantage over the annual-based system it replaces; (iii) a robust management package; and (iv) a viable seed supply. The findings of this review highlight that perennial pastures must indeed satisfy multiple criteria to be commercially successful. Notably, the requirement for the source of the germplasm to have a good match between climate and soils is less clear because some of the commercially successful species come from diverse environments. We conclude with some key learnings for future perennial pasture development as climate change intensifies the research challenge and the drive for producers to adapt.

Soils with toxic levels of boron (B) are widespread in the cereal-livestock zone of southern Australia. The annual pasture legume burr medic (Medicago polymorpha L.) is widely grown in rotation with grain crops in this zone, but current cultivars are susceptible to high levels of B. We tested the boron tolerance of several putative B tolerant burr medic accessions and developed four F₂ populations by crossing two tolerant accessions with two susceptible cultivars. We tested a B tolerance SSR marker developed for barrel medic (M. truncatula Gaernt) on tolerant burr medic accessions but found a new marker was required. We identified several B tolerant burr medic accessions. In our four F₂ populations tolerance was inherited in a 3 : 1 (tolerant : susceptible) ratio and we identified a molecular marker that accounts for 0.84 of the variation. The B tolerant accessions, along with the B tolerance marker, will allow for the efficient introgression of B tolerance into widely adapted genetic backgrounds and will allow breeders to efficiently develop cultivar(s) that are tolerant of a widespread subsoil constraint.

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.

Perennial legumes have potential to increase pasture productivity in the high rainfall zone (600–850 mm) of south-eastern Australia through their ability to use summer rainfall and fix nitrogen (N₂). Various perennial legumes are being evaluated for this environment; however, little information exists on legume–rhizobia cross-host compatibility and its consequences for biological N₂ fixation. This is especially important when legumes are sown into fields with a background of competitive rhizobia such as WSM1325 or sown as a pasture mix with different host–symbiont pairs. We studied the effectiveness and cross-host compatibility of five commercial rhizobial strains for a range of pasture legumes (nine species, 18 cultivars) under controlled environment conditions, and further evaluated nodule occupancy and competitiveness of a newly established pasture (13 species, 20 cultivars) in the field, by determining nodulation and production (biomass and N₂ fixation). Three of the commercial inoculant strains formed root nodules with multiple legume species; commonly however, less N₂ was fixed in cases where the inoculant was not the recommended strain for the legume species. Within a legume species, cultivars could differ in their ability to form effective root nodules with multiple rhizobial strains. White clover cvv. Trophy, Haifa and Storm, strawberry clover cv. Palestine, and Talish clover cv. Permatas formed effective nodules with both TA1 and WSM1325 rhizobial strains. White clover cultivars that could not form an effective symbiosis with the common background strain WSM1325 fixed less N_2. The white clover × Caucasian clover hybrid formed effective symbiosis with strain TA1 but not with other commercial strains. Some species such as birdsfoot trefoil, Talish clover, sulfur clover and tetraploid Caucasian clover formed ineffective symbiosis in the field. Until resolved, this will likely inhibit their further development as pasture plants for similar permanent pasture environments.

Increases in temperature, along with possible decreases in rainfall, will influence the production of forage on Australian dairy farms. A biophysical simulation study was undertaken to compare the performance of perennial pastures and annual forage cropping systems under a historical scenario and two possible future climate scenarios for three key dairy locations of south-eastern Australia. Pastures and forage-cropping systems were simulated with the biophysical models DairyMod and APSIM, respectively, for a location with a heavy reliance on irrigation (Dookie, Victoria), a location with a partial reliance on irrigation (Elliott, Tasmania), and a dryland location (Terang, Victoria). The historical climate scenario (baseline scenario) had no augmentation to climate data and an atmospheric CO₂ concentration of 380 ppm, whereas the two future climate scenarios had either a 1°C increase in temperatures (with an atmospheric CO₂ concentration of 435 ppm) and a concurrent 10% decrease in rainfall, or a 2°C increase in temperatures (with an atmospheric CO₂ concentration of 535 ppm) and a concurrent 20% decrease in rainfall. At Dookie, mean annual dry matter yields of the forage-cropping options and the pasture systems increased under both future climate scenarios but more irrigation was required. At Terang, the yield of forage-cropping systems increased whereas the yield of the pasture systems decreased under the future climate scenarios. At Elliott, yields of irrigated pastures and cropping systems increased but there was minimal or a negative impact on yields of dryland pastures and cropping systems under the future climate scenarios. At all three locations, forage production increased in the colder months of the year with a decrease in production during the warmer months. This study indicates that double-cropping and irrigated-pasture systems at all three locations appear resilient to projected changes in climate; however, for irrigated systems this assumes a reliable supply of irrigation water. The systems implications of how a shift in the seasonality of forage supply within these options impacts on the farm system as a whole warrants further investigation.

In northern Victoria, Australia, perennial pastures for the dairy industry have historically been based on perennial ryegrass. However, perennial ryegrass does not perform well under high summer temperatures and water stress. We investigated irrigation, renovation and grazing management strategies for improving the resilience and survival of perennial ryegrass over summer on two farms in northern Victoria over 2.5 years. At each farm, two irrigation bays were sown in March 2015. During summer (late December–mid-March), one bay was not irrigated and the other bay received a single mid-summer irrigation. Each bay was sown to 12 ryegrass cultures: five cultivars of perennial ryegrass either oversown or not oversown, and two oversown cultivars of short-lived ryegrass (SLRG). A mid-summer grazing treatment was applied to one-half of each of these plots. All plots at both sites received the same irrigation and grazing management at other times of the year. There were significant variations in dry matter (DM) production, nutritive characteristics and plant frequencies across sites and seasons, and across renovation, irrigation and grazing management strategies. Cumulative DM yields were higher in the perennial ryegrass than the SLRG cultivars. Summer DM removal was very low at both sites; the ungrazed plots recovered and produced more DM in the following cooler period than the grazed plots in the first year but not the second. Metabolisable energy concentration was higher for perennial ryegrass than SLRG cultivars and was also higher in plots that had been grazed over the summer. There were large differences in plant frequency between species, and there were some differences among perennial ryegrass cultivars. The effect of summer grazing on plant frequency varied at each site and was not significant within an irrigation treatment. This research confirms that perennial ryegrass is not well suited to the hot, dry summers of northern Victoria and suggests that, under conditions of limited summer irrigation, farmers should focus on plant survival rather than summer yield if they are to maximise annual DM production.

Tropical perennial grasses are an important forage option in the frost prone, summer dominant rainfall zone in eastern Australia. These pastures commonly lack a companion legume and are, at best, irregularly fertilised with nitrogen; therefore, their production potential is not realised. We conducted a study during 2012–16 to evaluate the productivity and persistence of a range of cultivars/lines of eight tropical and two temperate perennial legumes in mixes with digit grass (Digitaria eriantha cv. Premier) at two sites (Bingara and Manilla) in the northern inland region (North-West Slopes) of New South Wales. The sites were subjected to dry conditions during the assessment period, with the Bingara site receiving <25th percentile rainfall for 2 years of the study. Lucerne (Medicago sativa) was the most productive companion legume, with mixes producing 16–18 and 38–46 t dry matter (DM)/ha at the Bingara and Manilla sites respectively. Cultivars of Desmanthus spp. were less productive, with the best performing in mixes producing 13 and 21–23 t DM/ha at Bingara and Manilla respectively. These cultivars were also persistent and readily recruited new seedlings. Their persistence was similar or superior to lucerne, which appeared to be declining, especially at the Manilla site. Mixes of burgundy bean (Macroptilium bracteatum) and digit grass produced 14–17 t DM/ha at the sites but DM tended to decline during the course of the experiment, especially at the Manilla site. Stylosanthes spp. and Chamaecrista rotundifolia had poor persistence, generally failing within 1–2 years of sowing. Therefore, we recommend lucerne and Desmanthus virgatus cvv. Marc and JCU 2 as suitable perennial legumes in mixes with digit grass during drought conditions.

Spatial separation of species at sowing has been proposed as a means of managing interspecific competition in mixed swards. This study examined the effect of row configuration on persistence of lucerne (Medicago sativa L.) in pastures and pasture–cover crop mixtures at three sites in the Central West, and in pasture mixtures at three sites in the Riverina, New South Wales, Australia. Lucerne density, taproot diameter, groundcover, and spatial distribution relative to the original drill row were measured at all sites, and plant-available soil water and light interception during spring were assessed at some sites. Row configuration (alternate or mixed drill rows) did not affect lucerne persistence; however, where lucerne seed was concentrated in every third drill row, intraspecific competition led to increased lucerne mortality. This was estimated to occur at densities >28 plants/m drill row. A lucerne density of ∼55 plants/m² in every or alternate drill rows (at row spacings of 250 mm) would likely achieve maximum lucerne production in the semi-arid environments tested, subject to the chance event of favourable conditions in the period after sowing that would maintain that density (e.g. cumulative summer rainfall >100 mm and summer day degrees <2160°C in 2 years at Cowra). The presence of a cover crop in the establishment year reduced lucerne density by 39% compared with pasture only, regardless of row configuration. Changed row configuration did not reduce competition for light under a cover crop, but there was a small increase in available soil water of up to 4.9 mm in the 0–1.15 m depth, mainly during the first summer, where pasture was sown in alternate compared with mixed drill rows with a cover crop. Soil was drier in pasture-only treatments than those with a cover crop, attributable to increased lucerne density and lower levels of litter cover on the soil surface. Pasture species remained largely confined to the original drill row, especially in drier environments, highlighting the importance of narrower row spacings for pasture establishment. In addition, we determined a mathematical relationship between lucerne density and the non-destructive measure of basal frequency; this relationship could be applied in mature lucerne stands with densities ≤80 plants/m².

There is very little robust, experimentally based knowledge comparing drought tolerance of one legume species with another. Dehydration tolerance and plant survival of the perennial legumes white clover (Trifolium repens L., considered quite sensitive to drought) and lucerne (Medicago sativa L., considered drought tolerant) were compared in a drying cycle experiment conducted in pots in a glasshouse, with the deep rooting of lucerne constrained. White clover used more soil water, drying the pots to a final soil gravimetric water content (θ_g) of 4.7%, compared with 8.3% in lucerne pots. Rates of water use were also different: white clover used 0.47% of θ_g per day and lucerne 0.3%. The more conservative water use allowed lucerne to survive for longer into the drying cycle than white clover. Lucerne partitioned more of its total dry matter into root growth and had much higher root:shoot ratios than white clover. Leaf/stolon elongation is one of the first plant processes to cease as water deficit increases; however, elongation was greater in white clover than lucerne at the beginning of the drying cycle, and this trend continued until lower soil water contents were reached. Conversely, leaf senescence generally commenced at quite high levels of water stress and progressed more rapidly to complete senescence in white clover than in lucerne. Lucerne retained tissue relative water content at a higher level than white clover, with final minimum values of 25% and 13.6%, respectively. In lucerne, 50% mortality was observed at θ_g of 9%, compared with 6% in white clover, albeit with greater variability. In conclusion, lucerne maintained a higher relative water content than white clover even though it endured the drying cycle for longer and without access to water at depth, evidence of its superior dehydration avoidance and better adaptation to dry conditions. However, white clover was more able to extract water from surface soil layers. This study provides valuable insight into the adaptive traits of both species and identifies some traits that might be useful in the quest to improve white clover adaptation.

Phosphatic fertilisers have made grazing in the south-west of Western Australia (WA) viable. However, there is evidence that a large proportion of pasture paddocks exceed soil test critical values at which 95% of maximum yield is achieved as identified in the national Better Fertiliser Decisions for Pasture (BFDP) project. Of 22 000 soil samples collected between 2009 and 2020, 56% exceeded the critical value for phosphorus (P), although there were constraints to potassium (K) and sulfur (S) and from soil acidity. Soils with available P exceeding the critical value are expected to lead to excessive losses of P to waterways, resulting in eutrophication. A trial program was established to validate the critical P values from BFDP so that concerns can be addressed about the relevance of these critical P values to WA conditions and to contemporary pasture varieties. Measured relative yields for 19 trials in the first year were mostly within 10% of that predicted from BFDP for soils with a P buffering index (PBI) >10. Soils with PBI <10 had measured relative yields up to 25% greater than predicted by BFDP, suggesting response calibrations for low PBI soils may require adjustment in the BFDP dataset. Some pasture yield gaps occurred when soil pH and P were low. Application of nitrogen (N), K and S almost doubled the yield when P was limiting or sufficient. Agronomic advice and practice should seek to optimise these multiple inputs, thereby optimising P use rather than applying P to levels above the critical value.

The extensive grazing systems of northern Australia are dominated by C₄ grasses and are established in N- and P-responsive soils that receive minimal nutrient input. Under these conditions, tropical pasture legumes are expected to improve the quality of grazing forage and fix atmospheric N₂. However, legume persistence is relatively poor, which may be due to a presumed disparity in P requirements among tropical pasture species. This disparity suggests that P-efficient legumes may improve legume persistence, yet the P requirements of many tropical pasture legumes remain unquantified. Nine Desmanthus spp. genotypes were grown in pots to determine differences in shoot yield and root morphology in response to soil P supply (0–100 mg applied P kg^–1 soil; 5–63 mg Colwell P kg^–1 soil). The shoot yield of each genotype increased in response to increased P supply. When P supply was adequate for maximum plant growth, the shoot yield of the best genotype (3.5 g DM pot^–1; JCU 9) was 1.7-fold larger than that of the next most productive genotype. There were also substantial differences in the critical external P requirements of the genotypes (29.4–64.0 mg P kg^–1 soil), although these differences did not always reflect the efficiency of dry matter production per unit of applied P fertiliser. Differences in shoot yield and P acquisition were positively associated with differences in the development of root length. The results indicated that P-efficient genotypes of Desmanthus spp. can be identified for improved growth in the P-responsive pastures of northern Australia. These genotypes may compete more effectively with C₄ grasses and form resilient pasture swards as climate patterns change.

Messina (Melilotus siculus) is a new annual pasture legume with better combined waterlogging and salt tolerance than other annual legumes. Messina cv. Neptune and a new salt-tolerant rhizobial symbiont (Sinorhizobium medicae SRDI-554) were made available to Australian growers in 2017. Messina is related to the annual medics (Medicago spp.) that are nodulated by the same genus of rhizobia and regarded as sensitive to soil acidity. Because some saltland soils are acidic, it is important to understand the sensitivity of messina to soil acidity in order to avoid failures during early adoption.

Acidity tolerance of the messina–Sinorhizobium symbiosis was investigated in a hydroponic experiment (inoculation with SRDI-554, or the salt-intolerant strain WSM-1115 recommended for medics), and in three acidic soils (pH_Ca 4.3–5.5) (inoculation with SRDI-554 ± lime pelleting of seed), in the greenhouse.

In the hydroponic experiment, the percentage of messina plants (with SRDI-554) that formed nodules declined at pH levels between 5.7 (43%) and 5.5 (4%). Strain SRDI-554 was slightly more sensitive to acidity than strain WSM-1115. In the acidic soils, more plants formed nodules than in the hydroponic experiment at similar pH levels; however, without lime pelleting, nodule number was inadequate at soil pH_Ca <5.5. Addition of lime to seed was beneficial to messina nodulation. Nodule number per plant increased from 4.0 to 9.6 with the addition of lime.

The messina–Sinorhizobium symbiosis was confirmed as sensitive to low pH. At pH_Ca 5.5, which is the level recommended as the lower limit for growing messina, nodule number was constrained in both hydroponics and soil. The risk of suboptimal nodulation would be reduced if the recommended lower soil pH limit for growing messina is increased to pH_Ca 5.8, in line with most annual medics. Efforts to improve the acidity tolerance of the messina symbiosis would be best focused on the rhizobial symbiont, rather than the plant.

Ground pearls (Hemiptera: Margarodidae), so called for their shiny spherical cyst stage, are important root-feeding pests of a broad range of plants predominantly belonging to the family Poaceae. In the tropical and subtropical regions of eastern Australia, ground pearl species cause significant damage on sugarcane and turf grasses and have been identified at multiple sites of pasture dieback in Queensland. The potential impact of ground pearls on pasture production in Australia and elsewhere is largely unknown. This paper reviews Australian and international literature on the biology and management of this poorly understood group of pests. Ground pearls have several features that make control difficult, including a resilient cyst which provides resistance to drought and excessive moisture, a relative impermeability to insecticides, and ease of dispersal through movement of soil. Ground pearls can also modulate the period of encystment to survive adverse environmental conditions, with some species capable of surviving for years while disassociated from a host. No insecticide effectively controls ground pearl cysts. Biological control agents have been identified for some species; however, these pathogens are relatively ineffective on subterranean ground pearl cysts. Cultural control methods such as cultivation and fallowing have helped to reduce ground pearl populations in sugarcane. In turf, practices that maintain plant health such as adequate irrigation and nutrition can mask signs of ground pearl infestation. The paucity of research conducted on the biology and impact of ground pearls represents a constraint to improving management of this pest.