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Context: Herbicide-resistant annual ryegrass (Lolium rigidum ; ARG) is a major weed of commercial significance globally, including no-till wheat-based production systems in south-eastern Australia. Aims: To compare the cost-effectiveness of different crop sequences and intensities of weed management to control ARG in rainfed grain production. Methods: Two on-farm studies in southern New South Wales, Australia, compared the effect of combinations of 3-year crop-sequence options (continuous wheat, 1- or 2-years of break crops), conservative or aggressive weed-control measures, hay cuts, legume brown manure (BM), and/or weed-free winter fallow on in-crop ARG infestations and soil seedbanks. Gross margins were calculated for each combination of treatments to compare system economic performance. Key results: Double-breaks consisting of two consecutive broadleaf crops, or canola–cereal hay, were frequently the most profitable and effective ARG control strategies. Single canola or lupin crops, BM, cereal hay, and fallow all significantly reduced subsequent in-crop ARG and seedbank numbers compared with continuous wheat. Aggressive in-crop control measures in wheat were more expensive than those applied to break crops. Gains in ARG control could be lost by a single year of poor weed control. Conclusions: High levels of control (>95%) over three consecutive seasons are required to reduce ARG seedbanks, and this is most cost-effectively achieved with diverse crop sequences. Implications: Farmers with high populations of ARG can reduce seedbanks by growing three crops sequentially that achieve complete weed seed control. This must be followed with ongoing high levels of control in subsequent years to keep ARG seedbanks low. The paper reports the outcomes of two on-farm experiments that aimed to identify the most cost-effective strategies to control herbicide-resistant annual ryegrass in rainfed, no-till, wheat-based farming systems in southern NSW. The studies linked efficacy of annual ryegrass control with the relative profitability of combinations of different crop sequences and agronomic management. The results showed that three consecutive years of >95% weed control by using diverse crops are required to cost-effectively reduce annual ryegrass seedbanks in soil to manageable levels. [ABSTRACT FROM AUTHOR]

Systematic measurement of pasture biomass (kg DM/ha) is crucial for optimising pasture utilisation and increasing dairy farm profitability. On-farm pasture monitoring can be conducted using various sensors, but calibrations are necessary to convert the measured variable into pasture biomass. In this study, we conducted three experiments in New South Wales (Australia) to evaluate the use of the rising plate meter (RPM), pasture reader (PR), unmanned aerial vehicles (UAV) and satellites as pasture monitoring tools. We tested various calibration methods that can improve the accuracy of the estimations and be implemented more easily on-farm. The results indicate that UAV and satellite-derived reflectance indices (e.g., Normalised Difference Vegetation Index) can be indirectly calibrated with height measurements obtained from an RPM or PR. Height measurements can be then converted into pasture biomass ideally by conducting site-specific sporadic calibrations cuts. For satellites, using the average of the entire paddock, root mean square error (RMSE) = 226 kg DM/ha for kikuyu (Pennisetum clandestinum Hochst. ex Chiov) and 347 kg DM/ha for ryegrass (Lolium multiflorum L.) is as effective as but easier than matching NDVI pixels with height measurement using a Global Navigation Satellite System (RMSE = 227 kg DM/ha for kikuyu and 406 kg DM/ha for ryegrass). For situations where no satellite images are available for the same date, the average of all images available within a range of up to four days from the day ground measurements were taken could be used (RMSE = 225 kg DM/ha for kikuyu and 402 kg DM/ha for ryegrass). These methodologies aim to develop more practical and easier-to-implement calibrations to improve the accuracy of the predictive models in commercial farms. However, more research is still needed to test these hypotheses under extended periods, locations, and pasture species. [ABSTRACT FROM AUTHOR]

Herbicide resistance is an important weed management issue. Glyphosate is the most dominant herbicide, which controls a broad spectrum of weeds, including grasses such as Lolium rigidum. Lolium rigidum is a major weed of winter crops in Australia that is developing glyphosate resistance in increasing numbers of populations and has been observed growing throughout summer in recent years. Three L. rigidum populations, one summer-emerging glyphosate-resistant (GR), one winter-emerging glyphosate-susceptible (GS), and one winter-emerging population with unknown resistance status (CC04), were analyzed for target-site resistance to glyphosate after confirming their resistance or susceptibility to glyphosate in a dose–response experiment. Population GR was obtained from plants that emerged in summer and contained plants that survived all rates of glyphosate applied (0 to 4560 g a.e. ha−1). It was found to be 6.1 and 4.4 times more resistant than population GS across two experiments. Population CC04 was identified as susceptible. Plants from each population were analyzed for the presence of target-site mutations in the conserved region of the EPSPS gene; however, no mutations were identified that could cause resistance, suggesting non-target-site resistance in population GR. The effectiveness of alternative herbicides was also analyzed for each population. Paraquat was the most effective herbicide, with 0% survival across all populations. The ACCase-inhibiting herbicide clethodim was also highly effective (0 to 8% survival across populations). Other ACCase-inhibiting herbicides, propaquizafop, haloxyfop, and pinoxaden, were effective at controlling the two susceptible populations, CC04 and GS (0 to 36% and 0 to 20% survival, respectively), but were only moderately effective for controlling GR (28 to 51% survival). Paraquat and clethodim may be alternative options for controlling GR populations of L. rigidum and could be effective for use in management programs to slow the development of GR populations. [ABSTRACT FROM AUTHOR]

Context: Lolium rigidum Gaudin (annual ryegrass) has remained the most problematic weed of crop production in Australia for more than 20 years. There is some evidence that this weed species can rapidly adapt to management practices including delayed crop sowing. Aims: Studies were undertaken to determine genetic variation for seed dormancy within L. rigidum populations and its association with genes involved with gibberellic acid and abscisic acid synthesis. Methodology: Populations of L. rigidum were grown in pots to select low and high dormancy cohorts. Seeds produced by these cohorts from each population were assessed for variation in seed dormancy. Seeds of high and low dormancy cohorts were concurrently assessed for seed dormancy and expression of LrABA1 and LrGA20ox genes, using quantitative real-time PCR. Results: Presence of differences greater than two-fold in seed dormancy between populations from the same farm indicated in situ selection for seed dormancy, most likely in response to management. Low and high dormancy cohorts of all populations maintained clear differences in seed dormancy in both years of assessment. Differences in seed dormancy between low and high dormancy cohorts were significantly correlated with LrABA1 and LrGA20ox gene expression. Conclusions: This investigation has provided clear evidence of the presence of genetic variation for seed dormancy within L. rigidum populations. Implications: The presence of genetic variation for seed dormancy in L. rigidum populations will allow this weed to adapt rapidly to changes in weed management practices such as delayed sowing of crops. Lolium rigidum is one of the most problematic weeds of cereal crops in southern Australia. Seed dormancy of different L. rigidum populations was analysed, and genes responsible for the control of seed dormancy were identified. Findings from our research enhance understanding of the genes involved in regulating seed dormancy, their expression over time, and how loss of dormancy is associated with changes in gene expression. [ABSTRACT FROM AUTHOR]

Context: Annual ryegrass (Lolium rigidum) is a major weed of crop production in southern Australia that readily develops resistance to herbicides. Resistance increases both yield losses and control costs associated with this species. Aims: This study aimed to gauge the extent and distribution of resistance to herbicides in L. rigidum across south-eastern Australian grain production systems by collecting seed from randomly selected fields. Methods: A total of 1441 weed populations were collected through random surveys conducted over 5 years across 13 agricultural regions of four states with these samples then tested for resistance to eight herbicides from six modes of action. Key results: Resistance to diclofop-methyl and sulfometuron-methyl was most common, being present in 64% and 63% of populations respectively. Glyphosate resistance was present in 4% of populations collected. Only 15% of populations collected were susceptible to all herbicides tested. Large differences in resistance occurred between the 13 regions surveyed with resistance to diclofop-methyl ranging from 15% to 86% of populations and sulfometuron-methyl from 12% to 96%. Resistance to post-emergent herbicides tended to be higher than pre-emergent herbicides. Multiple resistance was common with 60% of populations collected having resistance to two or more herbicide modes of action. Conclusions: There were significant differences in the extent of multiple resistance in L. rigidum populations collected from individual regions suggesting that the rates of resistance evolution have differed between regions. Implications : The high incidence of herbicide resistance in L. rigidum populations randomly collected from south-eastern Australian cropping fields highlights the need for the adoption of additional weed control practices to mitigate the impact of this species on grain production systems. Herbicide resistant weeds are a major threat to crop production, with annual ryegrass being the major species of concern in Australia. Surveys of south-eastern Australia conducted over a 5 year period found over 60% of populations were resistant to two or more herbicide groups and only 15% of ryegrass populations were susceptible to all tested herbicides. The high level of resistance found across south-eastern Australia highlights the need for farmers to adopt non-herbicide practices, in conjunction with herbicides, to control this species. [ABSTRACT FROM AUTHOR]

Australia has tropical, summer dominant rainfall in the north transitioning to temperate, winter dominant rainfall in the south. Temperate pasture species with a cool season growth pattern are commonly grown in the south, but tropical pasture species that are highly productive and responsive to summer rainfall, may also have a role in southern pasture systems with climate change. Determine the value of replacing temperate pastures with tropical pastures; and assess the emergence success of tropical grasses in response to historic climate change in eastern Australia. The AusFarm model was used to test replacing lucerne (Medicago sativa L.) (L); annual ryegrass (Lolium rigidum L.)/subterranean clover (Trifolium subterraneum L.) (RC); or lucerne/annual ryegrass/subterranean clover (LRC) with tropical pasture at varying rates of inclusion at five locations across the subtropical-temperate transition zone. The emergence success of tropical grasses with a bare fallow, short fallow and increased ground cover management was also tested. The modelling covered two periods, the Far Climate (1960–1990) and the Near Climate (1990–2020). Tropical pastures had higher plant growth in late summer-early autumn when temperate pastures are less active. Pasture growth decreased from the Far to the Near Climate period across all sites. The pastures with L lost the most production over this period, with minimal change in other pasture types. Supplementary feeding was reduced at all sites with the inclusion of tropical pastures. The cost of supplementary feeding from the Far to the Near Climate increased by $20/ha with increased variability between years, which in-turn decreased gross margin by an average of $26/ha. Tropical pastures improved profitability on average by $24/ha (11%), but with different responses between environments. At the low rainfall sites (Condobolin and Leeton) there was a substantial benefit when tropical grass-clover (TC) pasture replaced L, but at the higher rainfall sites (Cowra and Wagga Wagga) the benefit was replacing RC with TC. There was a gradient of successful emergence from very high (>90%) in the north, to reduced opportunities in the south (<45%), and marginal influence of sowing management. Adding tropical pastures to grazing systems with temperate pastures increased summer-autumn growth, the animal requirements met by pasture, and gross margins. Profitability of livestock systems decreased with climate change, but this can be overcome by optimising pasture composition. Fewer years are favourable for establishment of tropical pastures in more temperate environments, therefore establishment strategies need to be adjusted and field tested. • Tropical pastures have potential in temperate grazing systems due to climate change. • Tropical pastures increased plant growth over summer when temperate pastures are less active. • Tropical pastures decreased supplementary feeding and increased gross margin. • Poor establishment conditions limit the use of tropical grasses in temperate environments. • Profit of livestock systems decreased with climate change but less so with tropical pastures. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne L.) is considered the most important pasture species in temperate agriculture, with over six million hectares of sown area in Australia alone. However, perennial ryegrass has poor persistence in some environments because of low tolerance to a range of both abiotic and biotic stresses. To breed perennial ryegrass, cultivars with greater persistence and productivity may require evaluation of genotypes over a number of years. Persistence assessment in pasture breeding depends on manual ground cover estimation or counting the number of surviving plants or tillers in a known area. These methods are subjective and labour intensive, which may limit data collection in large‐scale breeding programs. With the rapid development of sensors and image processing algorithms, image‐based high‐throughput phenotyping (HTP) is becoming commonplace in the breeding of major food crops. Image‐based HTP approaches consist of the deployment of a wide range of sensors on ground‐based or airborne platforms and data analysed through image processing pipelines. Image‐based HTP shows high potential for use in pasture phenotyping in breeding programs and may be able to reduce timeframes for releasing new cultivars. Moreover, existing image‐based HTP approaches could be further developed to include precise tools for phenotyping pasture persistence traits such as pasture senescence, botanical composition, pathogen and pest resistance. In this study, we reviewed existing image‐based HTP approaches in precision agriculture and discussed their feasibility for perennial ryegrass persistence estimation in pasture breeding. Although the paper focuses on application in perennial ryegrass, the principles equally apply to other perennial forage species. [ABSTRACT FROM AUTHOR]

The legacy of deliberate and accidental introductions of invasive alien species to Australia has had a hefty economic toll, yet quantifying the magnitude of the costs associated with direct loss and damage, as well as for management interventions, remains elusive. This is because the reliability of cost estimates and undersampling have not been determined. We provide the first detailed analysis of the reported costs associated with invasive species to the Australian economy since the 1960s, based on the recently published InvaCost database and supplementary information, for a total of 2078 unique cost entries. Since the 1960s, Australia has spent or incurred losses totalling at least US$298.58 billion (2017 value) or AU$389.59 billion (2017 average exchange rate) from invasive species. However, this is an underestimate given that costs rise as the number of estimates increases following a power law. There was an average 1.8-6.3-fold increase in the total costs per decade since the 1970s to the present, producing estimated costs of US$6.09-57.91 billion year-1 (all costs combined) or US$225.31 million-6.84 billion year-1 (observed, highly reliable costs only). Costs arising from plant species were the highest among kingdoms (US$151.68 billion), although most of the costs were not attributable to single species. Of the identified weedy species, the costliest were annual ryegrass (Lolium rigidum), parthenium (Parthenium hysterophorus) and ragwort (Senecio jacobaea). The four costliest classes were mammals (US$48.63 billion), insects (US$11.95 billion), eudicots (US$4.10 billion) and monocots (US$1.92 billion). The three costliest species were all animals - cats (Felis catus), rabbits (Oryctolagus cuniculus) and red imported fire ants (Solenopsis invicta). Each State/Territory had a different suite of major costs by species, but with most (3-62%) costs derived from one to three species per political unit. Most (61%) of the reported costs applied to multiple environments and 73% of the total pertained to direct damage or loss compared to management costs only, with both of these findings reflecting the availability of data. Rising incursions of invasive species will continue to have substantial costs for the Australian economy, but with better investment, standardised assessments and reporting and coordinated interventions (including eradications), some of these costs could be substantially reduced. [ABSTRACT FROM AUTHOR]

Context: Filling the summer–autumn feed gap is a key priority for sheep producers in southern Australia's high-rainfall zone. Aim: Our research aimed to determine whether spring-sown winter-type canola (Brassica napus L.) could increase herbage mass and nutritive characteristics during summer and autumn relative to other forage options in southern Australia's HRZ. Methods: A field experiment was conducted at Hamilton, Victoria, Australia, in 2014 and 2016 testing seven forage treatments replicated four times in the complete block design. The treatments were: canola (two treatments of different cultivars), forage brassica (B. napus), lucerne (Medicago sativa L.), chicory (Cichorium intybus L.), plantain (Plantago lanceolata L.) and perennial ryegrass (Lolium perenne L.). Key results: Herbage mass and nutritive characteristics of the canola varieties did not differ (P > 0.05) from forage brassica. Herbage mass in March 2014 was 3.35–3.64 t dry matter (DM)/ha for brassicas; 1.05–1.37 t DM/ha for perennial ryegrass, plantain and chicory; and 2.94 t DM/ha for lucerne (P < 0.001, l.s.d. = 1.20). In March 2016, herbage mass was 1.86–2.05 t DM/ha for brassicas and 2.14–2.49 for the other forage treatments (P < 0.05; l.s.d. = 0.47). Brassicas had higher (P < 0.05) metabolisable energy (ME) concentrations and lower (P < 0.05) neutral detergent fibre (NDF) concentrations on most sampling dates than chicory, plantain, lucerne and perennial ryegrass. The crude protein (CP) concentration of the brassica treatments was not different (P > 0.05) from that of the other forage treatments. Concentrations of ME, CP and NDF were very similar between years for the brassicas, with March ME, CP and NDF concentrations of 12.0–13.2 MJ/kg DM, 14.0–20.1% DM and 16.7–23.6% DM. Conclusion: Canola provided increased or equivalent levels of herbage mass and nutritive characteristics compared with other forage options in south-western Victoria on most, but not all, sampling dates. However, the annual spring-sowing requirement is a challenge under variable spring-rainfall conditions and may limit productivity if there is poor establishment. Implications: Spring-sown canola is a viable alternative forage for livestock producers and offers a potential second income stream in high-rainfall-zone livestock farming systems. Filling the summer–autumn feed gap is a key priority for sheep producers in southern Australia's high-rainfall zone, with summer and autumn traditionally being a time of feed shortage for livestock production. Winter-type canola can produce up to 3.5 t/ha of high-quality feed for grazing livestock during this key summer–autumn period. This provides livestock producers with the opportunity to increase production during this time of year, which could involve finishing livestock to higher slaughter weights or increasing the reproductive performance of ewes, utilising forage rather than purchasing supplementary feeds. [ABSTRACT FROM AUTHOR]

The aphid Aploneura lentisci is widespread in Australia and New Zealand, living all year round on roots of its secondary grass hosts. The fungal endophyte (Epichloë festucae var. lolii), strain AR37 in Lolium perenne is known to greatly reduce populations and was a likely reason for the superior growth and persistence of this association previously observed in the field. Aphid populations were quantified in a field trial near Ballarat, comparing yields of perennial ryegrass infected with eight different endophyte strains and an endophyte-free (Nil) control in a common ryegrass background (Grasslands Samson (G. Samson)). AR37 and another endophyte strain, AR5, had significantly fewer aphids than all other endophytes. These differences were significantly related to yield increases taken before and after sampling that persisted until the end of the trial. In a pot trial comparing commercially available ryegrass-endophyte combinations with equivalent Nil controls, aphid numbers were lower on G. Samson AR37 and Banquet II with AR5 (Endo®5) than on all other cultivar-endophyte combinations. Compared with Nil controls, the common toxic strain in G. Samson, and two strains in Trojan also reduced aphid numbers. The AR5 endophyte produces the alkaloid ergovaline but high concentrations of this in roots of potted plants could not account for differences in root aphid numbers. Root concentrations of epoxyjanthitrems, the only known alkaloids produced by AR37, were low and unlikely to be the cause of resistance to A. lentisci. An aphid, Aploneura lentisci , that feeds on grass roots is widespread in pastures in New Zealand and Australia. This paper reports data confirming that perennial ryegrass infected with a strain of Epichloë fungal endophyte, AR37, is highly resistant to this aphid and shows that another endophyte strain, AR5, gives the same level of control. Suppression of high aphid populations by these endophytes in the field at Ballarat resulted in a 37% increase in pasture production over endophyte-free ryegrass over a 5-month period. [ABSTRACT FROM AUTHOR]

Genotype-by-environment interaction (G×E) is commonly observed in perennial ryegrass species and significantly impacts dry matter yield (DMY) performance across environments. Variation in DMY of perennial ryegrass cultivars and their distinct responses to different environments directly influence the profitability of the Australian dairy industry. In this study, we implemented a separate two-way factor analytic strategy to fit multi-environment-multi-harvest data collected from 18 trials spanning 14 years to account for the G×E effects across complex pasture environments in south-eastern Australia to achieve accurate DMY predictions. Three mega-environments were identified, and the seasonal and environmental DMYs of 126 cultivars or breeding lines (defined by a combination of varieties and endophytes) were predicted. Statistical differences in DMY performance and crossover G×E effects in cultivar rankings were observed among the three mega-environments. Several high-yielding cultivars specific to each mega-environment were also identified. The analysis demonstrated the importance of accounting for G×E effects when predicting the DMY of perennial ryegrass and highlighted the potential for identifying high-yielding cultivars specific to mega-environments. The research rationalizes implementing an appropriate independent pasture trialling system to generate necessary data for the dairy industry and could further facilitate dairy farmers to select suitable cultivars based on their specific environments and perennial ryegrass breeders when accounting for the genetic relationship of cultivars. • G×E impacts perennial ryegrass cultivar rankings and breeding strategies. • Factor analytic model is a robust tool for analysing G×E. • Analysing G×E provides accurate DMY prediction and facilitates identifying high-yielding cultivars. • Identified 3 mega-environments and predicted DMYs for 126 cultivars. • Appling an independent trialling system is necessary to identify environmental-specific cultivars. [ABSTRACT FROM AUTHOR]

The nitrogen-use efficiency (NUE) of a fertiliser has implications for pasture growth and the environment. This study aimed to compare application of urea as a foliar spray or in granular form, to kikuyu (Cenchrus clandestinus (Hochst. ex Chiov.) Morrone) and short-rotation ryegrass (Italian ryegrass, Lolium multiflorum Lam.) pastures in the subtropical dairy region of eastern Australia. The first experiment was a replicated grazing study on a site with a high plant-available soil N (75 mg nitrate-N/kg). The granular rate of urea was 46 kg N/ha.month equivalent, and the foliar spray rate was 40% of the granular rate. Pasture growth rate (51 DM/ha.day with foliar spray vs 45 kg DM/ha.day with granules) and pasture consumed (4942 vs 4382 kg DM/ha) were not significantly different between treatments. However, over the 8 months of the study, soil nitrate-N levels fell from 75 to 22 mg/kg on the foliar plots but only fell to 60 mg/kg on the granular plots. The second experiment was a replicated plot-cut experiment on a site with a low plant-available soil N (8.7 mg nitrate-N/kg). The NUE for kikuyu grass was similar for all treatments with a mean of 14.8 kg DM/kg N for the four foliar treatments (high and low, with and without wetting agent) and 17.4 kg DM/kg N for the granular treatment. The NUE for the ryegrass was also similar for all treatments, with a mean of 13.2 kg DM/kg N for the foliar treatments and 15.8 kg DM/ha for the granular treatment. A third experiment, evaluating absorption of foliar-sprayed urea over time, found that >80% of the urea applied to kikuyu was absorbed by 7 h; for ryegrass, the amount absorbed was only ~45% but increased to ~75% if wetting agent was included. We suggest that the lack of benefit in NUE achieved by applying urea as a foliar spray, which contrasts with results from studies in temperate dairy farm systems, is primarily associated with the substantially lower tiller density and hence the smaller canopy area for absorption of the foliar spray by the new regrowth shoots post-grazing. This study compared the nitrogen-use efficiency (NUE) of urea applied as a foliar spray with that of the granular form in a subtropical climate. NUE was similar for both methods of application when applied to kikuyu (Cenchrus clandestinus) and short-rotation ryegrass (Lolium multiflorum) pastures. This was considered to be in part due to low tiller density and hence smaller leaf regrowth canopy for collecting the foliar spray than in temperate dairy regions. [ABSTRACT FROM AUTHOR]

Context: The Australian dairy industry is characterised by pasture-based feeding systems, where grazed pasture is commonly supplemented with cereal grain to increase milk production of dairy cows. Perennial ryegrass (PRG; Lolium perenne L.) is the most commonly used pasture species, with a wide range of cultivars available. However, the nutritive characteristics and the degradation of nutrients in individual PRG cultivars grown in different environments in Australia are unknown, and significant variation between cultivars may impact on supplementary nutrient requirements. Aims: The objective of this experiment was to quantify the extent of ruminal degradation of nutrients in three contrasting PRG cultivars (Bealey NEA2, Trojan NEA2 and Victorian SE) harvested during early spring and summer from Gippsland, northern Victoria and south-west Victoria in Victoria, Australia. Methods: Degradation parameters were determined by in situ incubation in the rumens of non-lactating, rumen-fistulated Holstein–Friesian cows for 72 h using a nylon bag technique. Key results: During both seasons, Bealey NEA2 had the greatest effective degradability of crude protein and neutral detergent fibre compared with Trojan NEA2 and Victorian SE. Cultivars harvested during early spring had greater effective degradability of crude protein and neutral detergent fibre, and a greater amount of rumen degradable protein compared with cultivars harvested during summer. Cultivars harvested from Gippsland had greater crude protein and neutral detergent fibre effective degradability, as well as a greater amount of rumen degradable protein, whereas cultivars harvested from northern Victoria had a greater amount of undegraded dietary protein. Conclusions: These results demonstrate that the ruminal degradation of PRG cultivars declines with increasing maturity, and that there are differences between cultivars and regions; however, differences between seasons are of a greater magnitude and are more important to consider when formulating optimal supplementary grain rations. Implications: This research has positive implications for farmers who will be able to understand the degradation of nutrients in PRG, and the amounts of rumen degradable protein and undegraded dietary protein available from pasture during each season. Farmers will be able to use this information to formulate supplementary grain rations that complement the nutrients from pasture and optimise milk production. Dairy production in south-eastern Australia is based on pasture-based feeding systems, where perennial ryegrass is the most common pasture species grown. This research provides novel information on the degradation characteristics of perennial ryegrass cultivars grown on farms in Australia, with degradability decreasing as the pasture matures. This will help farmers to formulate supplementary grain rations to match nutrient supply from pasture. [ABSTRACT FROM AUTHOR]

Research has shown advantages of including plantain (Plantago lanceolata L.) in grazed perennial ryegrass (Lolium perenne L.)-based dairy pastures. Plantain is typically established in dairy pastures during paddock renovation, and included in a mixture with perennial ryegrass. While perennial ryegrass can persist for years, even decades, plantain plant numbers and productivity decline within a few years of establishment. Maintaining the advantage of plantain requires frequent re-establishment. The current research tested the efficacy of two sowing methods (direct-drilling and broadcasting) and three sowing rates (2.5, 5.0, and 7.5 kg of seed/ha) for establishing plantain in existing irrigated perennial ryegrass pastures. Research was conducted on five dairy farms in northern Tasmania, Australia. Sowing occurred in mid-spring 2017, immediately after paddocks were grazed. Plantain establishment was monitored until early autumn 2018. Paddocks were managed as per normal farm practice, resulting in plantain being first grazed ~4 weeks post-sowing, before plants had developed to the recommended minimum six-leaf stage. Dry weather, timing of first grazing after sowing and insect burden challenged plantain establishment. However, both direct drilling and broadcasting were shown to successfully establish plantain into existing perennial ryegrass pastures. Plantain (Plantago lanceolata L.) can be included into perennial ryegrass (Lolium perenne L.)-based pastures to increase the productivity and profitability of dairy farming systems in south-eastern Australia; nonetheless, plantain is often underutilised, partly due to the shorter life span of plantain compared with perennial ryegrass. This research tested the efficacy of different sowing methods (direct-drilling vs broadcasting) in establishing plantain during spring in existing perennial ryegrass-dominated pastures. Both direct-drilling and broadcasting were successfully used to establish plantain in these pastures. [ABSTRACT FROM AUTHOR]

Improvement in nutritive characteristics resulting from breeding perennial ryegrass (PRG) cultivars used in Australia from the 1970s to the present day was quantified in a grazed field experiment in south-western Victoria. The experiment was sown in May 2014 with measurements undertaken over 3 years. The experiment contained 36 PRG treatments (cultivar–endophyte combinations), which were replicated four times, with herbage nutritive characteristics measured at each grazing. The treatments differed in estimated metabolisable energy (ME), crude protein and neutral detergent fibre (NDF) concentrations at each harvest date. The decade of cultivar release had little effect on the ME or the NDF concentration of the cultivars released from 1970s onward. Early season diploids had a lower ME concentration than did later-maturing diploid cultivars (11.0 vs 11.4 MJ/kg DM), predominantly due to a lower ME concentration in late spring and early summer (10.3 vs 11.1 MJ/kg DM). The tetraploid cultivars had a higher ME concentration (11.8 vs 11.4 MJ/kg DM) and a lower NDF (480 vs 505 g/kg DM) concentration than did the mid- and late-season diploid cultivars. These differences are likely to be of economic importance at the farm level. The genetic gain in nutritive characteristics of perennial ryegrass cultivars has not been quantified in dairy environments in Victoria. This work aimed to quantify these improvements, but found that most cultivar differences could be attributed to cultivar maturity and ploidy factors, with little effect of the decade of release. These cultivar differences are likely to be of economic importance at the farm level. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne L.) is the predominant perennial forage species used in temperate irrigated dairy-production systems in Australia. However, when temperatures are high, even with optimal irrigation strategies and nutrient inputs, dry matter (DM) production can be compromised. This research investigated the effects of perennial ryegrass and tall fescue genotypes and summer irrigation on (DM) production and survival. Ten perennial ryegrass cultivars, three hybrid ryegrasses and two cultivars of tall fescue (Festuca arundinacea (Schreb) Darbysh.) were sown in northern Victoria, Australia, in May 2014, and were managed under full irrigation or restricted irrigation (no irrigation between late December and mid-March) over a 3-year period. Measurements included net pasture accumulation (DM production), sward density (plant frequency) and water-soluble carbohydrate concentration. Apart from the expected differences in DM yield over the summer period between full irrigation and restricted irrigation, there were few differences in DM production among perennial ryegrass or tall fescue cultivars. Plant frequency declined significantly under restricted irrigation in Years 2 and 3 compared with full irrigation but there were no differences among perennial ryegrass cultivars. In Year 2, plant frequency was higher in the tall fescue cultivars than the ryegrass cultivars. The recovery pattern in DM production following recommencement of irrigation in mid-March (autumn) varied across years. In Year 1, plants recovered rapidly once irrigation recommenced in autumn. However, in Years 2 and 3, autumn and winter pasture accumulation under restricted irrigation was 30–35% less than under full irrigation. These differences were possibly related to decreases in plant frequency, as well as to differences in the amounts of residual pasture mass (or carbohydrate reserves) present when growth ceased. Analyses of the water-soluble carbohydrate concentrations in the pseudostem during summer and autumn in Year 3 showed differences in total water-soluble carbohydrate and in fructan and sucrose concentrations between irrigation treatments but no consistent differences among genotypes. Perennial ryegrass is the predominant perennial forage species in temperate irrigated dairy systems in Australia; however, its summer production can be poor. This research investigated the effects of genotype and summer irrigation on growth and survival of 15 perennial ryegrass and tall fescue genotypes. Dry matter production and plant frequency were reduced under restricted irrigation and there were few differences among cultivars, suggesting that plant performance over summer may be more influenced by irrigation management than by cultivar selection. [ABSTRACT FROM AUTHOR]

Abstract: Potassium fertilization in intensive grassland systems is particularly important on sandy soils with limited K storage capacity. A 3‐year plot experiment was conducted in south‐western Australia to determine the critical K concentration in herbage dry matter (DM) of annual and Italian ryegrass required to achieve 0.95 of the maximum yield, under best‐practice grassland management. A factorial design was employed with eight fertilizer K rates (range 0–360 kg ha−1 year−1) and two ryegrass species replicated four times, on a sandy soil site managed over 7 years to deplete mean soil Colwell K concentration to 42 mg/kg. Herbage was defoliated six times per year at the 3‐leaf stage of regrowth. Herbage DM yield, macronutrient and micronutrient concentrations were measured at each defoliation. Dry‐matter yield increased significantly (p < .001) with increasing levels of K fertilizer in all 3 years and the effect was curvilinear, while 0.95 of the maximum herbage DM yield was achieved at an annual K fertilizer application rate of 96, 96 and 79 kg/ha respectively. At these K fertilizer application levels, the mean K concentration of herbage DM over the 3 years was derived to be 11.4, 12.7 and 11.2 g/kg respectively. Sodium, magnesium and calcium concentrations of herbage DM all declined significantly (p < .001) as the K concentration increased. Grassland producers on sandy soils should target a K concentration in herbage DM of 16 g/kg for annual ryegrass and Italian ryegrass‐dominant swards to ensure K availability is not limiting herbage production. [ABSTRACT FROM AUTHOR]

A farm systems experiment comparing five pasture-based dairy systems was conducted in south-western Australia over 4 years on an annual ryegrass:subterranean clover sward. Fertiliser N inputs (0, 0.5, 1, 1.5 and 2 kg N ha−1day−1) and stocking rate (SR; 1.25, 1.50, 1.75, 2.0 and 2.25 milking cows ha−1) increased concurrently for each treatment (F1–F5, respectively). By design, milk yield per cow did not differ between treatments; therefore, the response was measured in terms of changes in herbage dry matter (DM) utilisation and nutritive characteristics, as well as differences in feed input and imported forage required. Total annual pasture utilisation (t DM ha−1) increased from treatment F1–F3 (5.1, 5.9 and 7.3 t DM−1ha−1, respectively), but responses beyond treatment F3 were not significant. Mean total N response efficiency was 9, 13, 8 and 7 kg DM per kg applied N for F2–F5, respectively, while mean marginal N response efficiency was 9, 17, −2 and 3 kg DM per kg applied N for F2–F5, respectively. The most efficient use of N fertiliser was achieved on treatment F3, where annual pasture utilisation levels in excess of 7 t DM ha−1yr−1were consistently demonstrated under the management strategies outlined, substantially greater than the local industry average. [ABSTRACT FROM AUTHOR]

Improved knowledge of the effects of climate change on farming systems can help increase long-term production, economic performance, and mitigate risk. Here we assessed the effects of stocking rate and seasonal calving times on pasture and milk production under short and long term climate changes on dairy farms in Tasmania, Australia. Annual and monthly perennial ryegrass pasture production was simulated from 1971 to 2065 to examine trends in pasture productivity, forage requirements, and impacts on milk production in 2015 and 2050. The projected future climate for the study region indicates a mean warming of up to 1.4 °C, with moderate declines in rainfall of up to 5%. Despite lower rainfall, climate change will likely have a positive impact on pasture yields, with annual production increasing by 13–16%, even though summer growth is reduced and inter-annual variability is increased. We found that greater pasture production is conducive to greater forage conservation, and together these factors allow intensification of stocking rates. These effects increase milk yields by 3–16% per annum and reduce reliance on purchased feeds, which together implies greater profitability of cool-temperate Australian dairy systems under future climates. We also found that total milk production in a spring calving system allows greater stocking rates and pasture utilisation compared with an autumn calving system, and whilst milk produced per animal declines under higher stocking rates, milk yield per hectare increases. Overall, our results suggest that global warming and climate change will positively affect pasture growth rates in Tasmania, and that greater production and conservation of home-grown feeds will be conducive to increased farm milk yields, provided that stocking rates are intensified sustainably. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (PRG) is an important forage grown on dairy farms in temperate regions globally, including south-eastern Australia. A forage value index (FVI) providing information on the seasonal production of commercially available PRG cultivars is currently available. Despite the importance of the nutritive value of pasture in dairy farm systems, the nutritive characteristics of PRG cultivars are not currently included in the FVI as they are not routinely measured in cultivar evaluation trials. This study investigated differences between cultivar functional groups (diploid and tetraploid). It also examined differences between individual cultivars within seasons at four locations in south-eastern Australia and examined how trial location affects cultivar ranking. Samples were collected from existing cultivar evaluation trials over a 3-year period and analysed for nutritive characteristics. There were differences (p < 0.05) between diploids and tetraploids for metabolisable energy (ME) and neutral detergent fibre (NDF) in each season at each location with a few exceptions in summer and autumn. Crude protein (CP) differed between functional groups in some seasons at some sites. Spearman rank correlations within season were strong for ME between trial locations (r = 0.78–0.96), moderate to high for NDF (0.51–0.86) and variable for CP (−0.69–0.56). These findings provide guidance on methods for implementing nutritive value testing in cultivar evaluation trials and support the imminent inclusion of ME in the Australian FVI. The ranking of cultivars for ME was more consistent across trial sites compared to NDF and CP, suggesting the latter two traits, in particular CP, are more sensitive to environmental influences. Based on these results, we do not recommend the inclusion of CP as an individual trait in the Australian FVI. A significantly larger dataset and further research on the genotype by environment interactions would be needed to reconsider this. The addition of ME in the Australian FVI will lead to better cultivar choices by farmers and could lead to more targeted perennial ryegrass breeding programs. [ABSTRACT FROM AUTHOR]

Abstract: Dairy systems in southern Australia rely on grazed feed from pasture to supply between 50% and 70% of total herd feed requirements on an annual basis. However, the dominant pasture type in the region, which is based on perennial ryegrass (Lolium perenne), commonly results in feed deficits in summer which must be filled with supplements purchased off-farm, and feed surpluses in spring which must be conserved. Both of these strictures impose costs on farm businesses. It is likely, therefore, that additional grazeable feed available to dairy herds in southern Australia may have different economic value when interactions between season, stocking rate, calving date, and locality are taken into account. The analysis reported in this paper aimed to estimate, using the farm systems simulation model UDDER, the effect of these interactions on the efficiency with which extra feed can be converted to extra milk production, and therefore the possible gross economic value of the additional feed. ‘Base’ farm simulations for ‘average’ and ‘top 10%’ farms (ranked according to farm profitability) in two localities (Terang: average annual rainfall 796mm, 8month growing season; and Ellinbank: average annual rainfall 1085mm, 9–10month growing season) were created to mimic the physical production and profitability of these farms as seen in regional farm benchmark datasets. These simulations were then altered to add the equivalent of 10% of the total annual herbage accumulation used in the Base simulation either on a pro-rata basis all year round, or in autumn only, in winter only, in spring only, or in summer only. The additional feed amounted to 620 and 780kg DM/ha for Terang average and top 10% farms respectively, and 735 and 905kg DM/ha for Ellinbank average and top 10% farms respectively. The management policies used in the Base simulations were then adjusted to harvest as much of the extra feed as possible, either by direct grazing or through silage conservation, while keeping the key system state indicators of cow condition score and average farm pasture cover within the limits known to result in long-term sustainable production. The efficiency with which extra feed was utilised was greatest in summer in all scenarios (80–100% of the extra feed supplied was harvested, all by direct grazing). This translated into consistently high gross economic returns of between $0.26 and $0.34per kg DM of extra feed added to the model. Utilisation efficiency was lower in all other seasons and/or required marked increases in silage conservation, both of which resulted in lower gross economic returns per kg DM of additional feed. The impact of interactions between locality, season, stocking rate (higher in top 10% farm simulations than average farm simulations) and calving date (earlier at Terang than at Ellinbank) were clearly captured in the model. These interactions have very large effects on the profitability of growing extra feed at different times of the year. Agronomic research for the southern Australia dairy industry should focus on low-cost ways for supplying additional grazeable feed in summer, since current forage species options for this time of year are limited. [Copyright &y& Elsevier]

Soil phosphorus (P) concentrations in excess of those required to maximise pasture production impose unnecessary costs on farmers and potentially increase the risk of P runoff to waterways. The relationship between soil available P concentration and pasture production was examined on an Oxyaquic Hydrosol. Mean annual pasture production ranged from 18,415 to 21,834 kg DM/ha over the 3-year sampling period. There was no significant difference in the annual DM production at Olsen P concentrations of 23-81 mg/kg measured from the 0-75 mm sampling depth. Results show that there was no increase in pasture production when soil Olsen P concentrations exceeded 23 mg/kg (0-75 mm). The optimum soil Olsen P ranges determined in the current study are well below the mean paddock concentrations previously measured in northwest Tasmania (54 mg/kg) and suggest that such high concentrations are not justified in terms of optimising pasture growth. [ABSTRACT FROM AUTHOR]

In Melbourne, Australia, airborne grass pollen is the predominant cause of hay fever (seasonal rhinitis) during late spring and early summer, with levels of airborne grass pollen also influencing hospital admissions for asthma. In order to improve predictions of conditions that are potentially hazardous to susceptible individuals, we have sought to better understand the causes of diurnal, intra-seasonal and inter-seasonal variability of atmospheric grass pollen concentrations (APC) by analysing grass pollen count data for Melbourne for 16 grass pollen seasons from 1991 to 2008 (except 1994 and 1995). Some of notable features identified in this analysis were that on days when either extreme (>100 pollen grains m) or high (50-100 pollen grains m) levels of grass pollen were recorded the winds were of continental origin. In contrast, on days with a low (<20 pollen grains m) concentration of grass pollen, winds were of maritime origin. On extreme and high grass pollen days, a peak in APC occurred on average around 1730 hours, probably due to a reduction in surface boundary layer turbulence. The sum of daily APC for each grass pollen season was highly correlated ( r = 0.79) with spring rainfall in Melbourne for that year, with about 60% of a declining linear trend across the study period being attributable to a reduction of meat cattle and sheep (and hence grazing land) in rural areas around Melbourne. Finally, all of the ten extreme pollen events (3 days or more with APC > 100 pollen grains m) during the study period were characterised by an average downward vertical wind anomaly in the surface boundary layer over Melbourne. Together these findings form a basis for a fine resolution atmospheric general circulation model for grass pollen in Melbourne's air that can be used to predict daily (and hourly) APC. This information will be useful to those sectors of Melbourne's population that suffer from allergic problems. [ABSTRACT FROM AUTHOR]

Abstract: Herbicide resistance in annual ryegrass (ARG, Lolium rigidum) threatens the quality and yield of winter wheat crops in Australia, prompting research to discover novel natural plant compounds with herbicidal properties. Due to its novel nature and potentially interesting chemistry, the Australian native, Wollemi pine (Wollemia nobilis), was tested for its ability to suppress ARG growth and its feasibility for use in weed control strategies. The leaf extract of Wollemi pine significantly inhibited the growth of ARG and wild radish (Raphanus raphanistrum) in laboratory bioassays at concentrations above 1% extract. In soil trials, the 100% extract (100g dried plant material/L) inhibited the dry weight of ARG by 25%. The addition of a wetting agent to the extract increased the suppression of ARG to 80% which was as phytotoxic as a 4-fold increase in the extract concentration (“400%” extract). Using bioassay-guided fractionation, the most phytotoxic fraction was identified and further analysed via GC/MS. Several compounds not previously identified in Wollemi pine leaf extracts have been identified, namely, 2-propylphenol, 3,4-dimethoxyphenol, 2-methoxybenzoic acid, vanillyl alcohol and isovanillic acid. These results suggest that Wollemi pine is an important potential source of compounds for the control of ARG and wild radish in winter crops. [Copyright &y& Elsevier]

Herbicide resistance in Lolium rigidum is widespread across much of the agricultural land in Australia. As the incidence of herbicide resistance has increased, so has the incidence of multiple herbicide resistance. This reduces the herbicide options available for control of this weed. This study reports on the successful amplification and sequencing of the acetolactate synthase (ALS) gene of L. rigidum using primers designed from sequence information of related taxa. This enables, for the first time, the successful determination of a mutation in the ALS gene of this species that provides resistance to ALS-inhibiting herbicides. This mutation causes amino acid substitution at Trp574 (numbering standardised to Arabidopsis thaliana) to Leu which had been reported to confer a high level of resistance against all classes of ALS inhibitor herbicides. In addition, multiple resistance to ALS-inhibiting and acetyl-coenzyme A carboxylase-inhibiting herbicides is acquired through the independent accumulation of mutant alleles for the target sites. This may thus explain some of the irregular, mosaic resistance patterns that occur in this predominantly outcrossing species. [ABSTRACT FROM AUTHOR]

Weed populations with resistance to glyphosate have evolved over the last 7 years, since the discovery of the first glyphosate-resistant populations of Lolium rigidum in Australia. Four populations of L. rigidum from cropping, horticultural and viticultural areas in New South Wales and South Australia were tested for resistance to glyphosate by dose-response experiments. All populations required considerably more glyphosate to achieve 50% control compared with a known susceptible population, indicating they were resistant to glyphosate. Translocation of glyphosate within these resistant populations was examined by following the movement of radiolabelled glyphosate applied to a mature leaf. All resistant plants translocated significantly more herbicide to the tip of the treated leaf than did susceptible plants. Susceptible plants translocated twice as much herbicide to the stem meristematic portion of the plant compared with resistant plants. These different translocation patterns suggest an association between glyphosate resistance in L. rigidum and the ability of glyphosate to accumulate in the shoot meristem. [ABSTRACT FROM AUTHOR]

Investigates the use of glyphosate in Australian cropping. Determination of the degree of soil disturbance at sowing; Simulating evolution of glyphosate resistance in Lolium rigidum; Level of adoption of reduced tillage crop establishment systems.

Abstract This field study investigated the effect of timing of nitrogen (N) fertilizer application in spring on the survival of grazed perennial ryegrass (Lolium perenne cv. Dobson and Yatsyn) over summer in a subtropical environment. There were five N fertilizer treatments: no applied N, 46 kg N ha-1 on 22 October or 22 November or 22 December, or on 22 October and again on 22 December. Water-soluble carbohydrate (WSC) concentration of perennial ryegrass plants entering the summer was altered by varying defoliation frequency, with defoliation interval based on the number of leaves per tiller. Frequent defoliation was set at a regrowth level of one leaf per tiller and less frequent defoliation at a regrowth level of three leaves per tiller, over a total of two by three-leaf per tiller regrowth periods. Application of N fertilizer was found to have no significant effect (P > 0·05) on survival of perennial ryegrass plants over summer. On the other hand, defoliation had a marked effect on perennial ryegrass persistence, with frequent defoliation decreasing ryegrass plant density (51 vs. 88 plants m-2 ; P < 0·001) and increasing the density of tropical weed grasses (99 vs. 73 plants m-2 ; P < 0·001) by autumn. Frequently defoliated plants had a lower stubble WSC content on a per plant basis than less frequently defoliated plants in spring (103 vs. 201 mg per plant; P < 0·001) and summer (59 vs. 101 mg per plant; P < 0·001). The lower WSC content was associated with a smaller root system in spring (1·50 vs. 2·14 g per plant; P < 0·001) and autumn (1·79 vs. 2·66 g per plant; P < 0·01), and this was reflected in 0·29 more plants being pulled from the soil by livestock between November 1996 and April 1997. Rhizoctonia fungus was associated with roots of pulled plants, but not with roots of seemingly healthy plants, indicating that this fungus... [ABSTRACT FROM AUTHOR]

The relative competitive advantage of 12 commercially available wheat varieties was examined against Lolium rigidum Gaud. at a number of sites from 1995 to 1997 in south-eastern Australia. Nearly all the variation in crop grain yield was attributable to the variety × environment effects (81%), with only 4% due to variety × weed × environment effects. Some varieties exhibited an environment-specific competitive advantage, for example Katunga, Dollarbird and Hartog, whereas others like Shrike, Rosella and Janz were relatively poorly competitive in some situations. The introduction of greater genetic variability into wheat is required to significantly increase competitiveness. Alternatively, manipulating crop agronomy, such as increasing crop seeding rate, may be a practical alternative. The grain yield of weed-free wheat was highly positively correlated with grain yield of the weedy plots, suggesting that local adaptation is important for strong competitiveness, and that wheat breeders in southern Australia may be inadvertently selecting for competitive advantage with weeds when selecting for other traits such as early vigour. The varieties which showed competitive yield advantage also suppressed L. rigidum. A combination of short-term agronomic manipulations and a longer-term breeding effort is needed for increasing wheat competitiveness, and the increasing importance of herbicide-resistant weeds may facilitate this process. [ABSTRACT FROM AUTHOR]

Following reports of poor weed control, the effectiveness of repeated applications of carbetamide and propyzamide in controlling Lolium rigidum Gaud, (annual ryegrass) was examined under field conditions. Repeated applications of carbetamide or propyzamide were less effective in controlling L. rigidum than an initial application. A single application of carbetamide or propyzamide was sufficient approximately to halve the efficacy of a subsequent treatment with the same herbicide. Laboratory incubations of soil linked the poor performance of carbetamide upon repeated application to an enhanced degradation rate. We conclude that the repeated application of carbetamide or propyzamide results in less effective weed control under field conditions and that this can be partially avoided by rotation between carbetamide and propyzamide. [ABSTRACT FROM AUTHOR]

The article discusses the use of nonchemical weapons by Australia's wheat farmers to control weeds. Topics include the introduction of ryegrass as forage for sheep imported from England, herbicide-resistance in ryegrass, the University of Western Australia's (UWA's) Australian Herbicide Resistance Initiative (AHRI), founded by Stephen Powles, and the Harrington Seed Destructor, which destroys ryegrass seeds before they can germinate.

The use of spectral data is seen as a fast and non-destructive method capable of monitoring pasture biomass. Although there is great potential in this technique, both end users and sensor manufacturers are uncertain about the necessary sensor specifications and achievable accuracies in an operational scenario. This study presents a straightforward parametric method able to accurately retrieve the hyperspectral signature of perennial ryegrass (Lolium perenne) canopies from multispectral data collected within a two-year period in Australia and the Netherlands. The retrieved hyperspectral data were employed to generate optimal indices and continuum-removed spectral features available in the scientific literature. For performance comparison, both these simulated features and a set of currently employed vegetation indices, derived from the original band values, were used as inputs in a random forest algorithm and accuracies of both methods were compared. Our results have shown that both sets of features present similar accuracies (root mean square error (RMSE) ≈490 and 620 kg DM/ha) when assessed in cross-validation and spatial cross-validation, respectively. These results suggest that for pasture biomass retrieval solely from top-of-canopy reflectance (ranging from 550 to 790 nm), better performing methods do not rely on the use of hyperspectral or, yet, in a larger number of bands than those already available in current sensors. [ABSTRACT FROM AUTHOR]

Crude protein estimation is an important parameter for perennial ryegrass (Lolium perenne) management. This study aims to establish an effective and affordable approach for a non-destructive, near-real-time crude protein retrieval based solely on top-of-canopy reflectance. The study contrasts different spectral ranges while selecting a minimal number of bands and analyzing achievable accuracies for crude protein expressed as a dry matter fraction or on a weight-per-area basis. In addition, the model's prediction performance in known and new locations is compared. This data collection comprised 266 full-range (350–2500 nm) proximal spectral measurements and corresponding ground truth observations in Australia and the Netherlands from May to November 2018. An exhaustive-search (based on a genetic algorithm) successfully selected band subsets within different regions and across the full spectral range, minimizing both the number of bands and an error metric. For field conditions, our results indicate that the best approach for crude protein estimation relies on the use of the visible to near-infrared range (400–1100 nm). Within this range, eleven sparse broad bands (of 10 nm bandwidth) provide performance better than or equivalent to those of previous studies that used a higher number of bands and narrower bandwidths. Additionally, when using top-of-canopy reflectance, our results demonstrate that the highest accuracy is achievable when estimating crude protein on its weight-per-area basis (RMSEP 80 kg.ha − 1 ). These models can be employed in new unseen locations, resulting in a minor decrease in accuracy (RMSEP 85.5 kg.ha − 1 ). Crude protein as a dry matter fraction presents a bottom-line accuracy (RMSEP) ranging from 2.5–3.0 percent dry matter in optimal models (requiring ten bands). However, these models display a low explanatory ability for the observed variability (R2 > 0.5), rendering them only suitable for qualitative grading. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne L.) is one of the most important forage grass species in temperate regions of Australia and New Zealand. However, it can have poor persistence due to a low tolerance to both abiotic and biotic stresses. A major challenge in measuring persistence in pasture breeding is that the assessment of pasture survival depends on ranking populations based on manual ground cover estimation. Ground cover measurements may include senescent and living tissues and can be measured as percentages or fractional units. The amount of senescent pasture present in a sward may indicate changes in plant growth, development, and resistance to abiotic and biotic stresses. The existing tools to estimate perennial ryegrass ground cover are not sensitive enough to discriminate senescent ryegrass from soil. This study aimed to develop a more precise sensor-based phenomic method to discriminate senescent pasture from soil. Ground-based RGB images, airborne multispectral images, ground-based hyperspectral data, and ground truth samples were taken from 54 perennial ryegrass plots three years after sowing. Software packages and machine learning scripts were used to develop a pipeline for high-throughput data extraction from sensor-based platforms. Estimates from the high-throughput pipeline were positively correlated with the ground truth data (p < 0.05). Based on the findings of this study, we conclude that the RGB-based high-throughput approach offers a precision tool to assess perennial ryegrass persistence in pasture breeding programs. Improvements in the spatial resolution of hyperspectral and multispectral techniques would then be used for persistence estimation in mixed swards and other monocultures. [ABSTRACT FROM AUTHOR]

• Accurate seasonal predictions of ryegrass cultivar DM yields using LMMs. • Base AR 37 and Bealy NEA2 were the best performing cultivars based on annual ranking. • Seasonal variability was found to be larger than genotypic variability. • An antedependence of order 3 was the best residual covariance structure for harvests. With over 60 commercial perennial ryegrass cultivars available on the market in Australia, selecting cultivars with high dry matter (DM) yield and economic profitability requires accurate estimates of their DM yield across target environments. This study, using data from multi-environment multi-harvest (MEMH) trials conducted in south-eastern Australia, derived accurate seasonal predictions of DM yield of these cultivars using linear mixed models (LMM). Base AR37 and Bealy NEA2 were found to be the best performing cultivars in most of the seasons in the target south-eastern Australian environments. Seasonal variability was found to be larger than genotypic variability as usually is the case in multi-environment trials. We have provided details of the LMM methodology used, along with ASReml-R code, to enable others to apply it in similar studies with appropriate changes as required for dataset used. The statistical theory underlying this methodology has also been briefly described in an Appendix for interested readers. [ABSTRACT FROM AUTHOR]

Fifty-three genotypes of perennial ryegrass selected from a range of cultivars and ecotypes were evaluated for their reaction to crown rust isolates collected from Western Australia, Victoria, Queensland, South Australia or New South Wales in Australia. The reactions of the clones to inoculation provided evidence for the development of a differential set of perennial ryegrass genotypes, but also demonstrated that a large number of genotypes displayed universal reactions to infection with any of the crown rust isolates. [ABSTRACT FROM AUTHOR]