Context. Legume and cereal mixtures can provide valuable feed for livestock.

Aims. A field experiment was conducted in 2016–2018 to determine the effect of the proportion of mixture components and harvest date on the total protein content and the content of amino acids in mixtures of field pea (FP) and spring triticale (ST).

Methods. Two factors were chosen for examination, the ratio of FP to ST and harvest date (at the flowering and flat green pod stages). The mixtures of FP:ST trialled were 100:0, 0:100, 75:25, 50:50, 25:75.

Key results. Dry matter yield was maximised with an equal proportion of both components harvested at the flat green pod stage of FP. The highest content of total protein, asparagine, glutamic acid, tyrosine, serine, proline and glycine in the examined mixtures was found with 75% FP and 25% ST. Cysteine content was highest with 25% FP + 75% ST. A highest content of total protein and analysed amino acids, with the exception of glutamine acid and proline, was found in mixtures harvested at flowering of FP.

Conclusions. A mixture of FP + ST with 75 + 25% or an equal share of both components should be recommended for cultivation, harvesting at the flat green pod stage of FP. This will ensure high dry matter yields and high total protein content.

Implications. Growing a mixture of FP + ST with a component share of 75 + 25% yields green fodder with high protein and amino acid content, whereas mixtures with equal component shares have the highest dry matter yields.

Context. Historical application of phosphorus (P) fertilisers has enabled grazing agriculture in south-west Western Australia but has led to excessive soil P levels that pose a eutrophication risk. However, adoption of critical soil-test P values for pastures determined from the Better Fertiliser Decisions for Pastures (BFDP) meta-analysis of historical Australian trials has been poor because of perceived lack of relevance to the soils and contemporary pasture species in the region.

Aims. We aimed to validate critical Colwell P values from the BFDP project for soils and contemporary pasture species of south-west Western Australia.

Methods. Fifty P-rate response trials were performed with contemporary pasture species, and the results compared with BFDP.

Key results. Trial results were consistent with BFDP and fell within 95% prediction intervals of response calibrations of Colwell P and relative yield pairs for different P buffering index (PBI) ranges. Soils with PBI <15 required lower critical Colwell P values. Responsiveness to P application was 8% (±4%), consistent with a 5% response expected for Colwell P levels supporting 95% relative yield. Application of nitrogen, potassium and sulfur significantly increased yield while increasing basal cover of annual ryegrass (Lolium multiflorum) and reducing that of clover (Trifolium spp.) in the sward. Response calibration coefficients and critical Colwell P values before and after addition of the trial data to BFDP showed a strong correlation (r² >0.99), although critical values were slightly lower for lower soil PBI.

Conclusions. Critical Colwell P values from BFDP are relevant and applicable to soils and contemporary pasture species of south-west Western Australia.

Implications. Agronomic advice and application of P should be based on interpretation of Colwell P values, with P applied only when levels are below the critical value. Pasture composition should also be considered when interpreting Colwell P values. This approach minimises risks of P loss and improves economic outcomes for growers.

Context. Crop production is one of the agricultural sectors most vulnerable to climate change. In order to minimise risks, innovative technologies and management strategies are continually being developed. Early sowing is a strategy used in wheat production; however, with irregular rainfall patterns, false breaks can occur.

Aims. We sought to determine the optimal volume of autumn-break rainfall for the start of season, and whether formation of a larger rhizosheath (i.e. the thick layer of soil adhering to roots) can buffer wheat seedlings from false-break conditions, thereby keeping plants alive until the next rainfall.

Methods. In glasshouse experiments, six varieties of common wheat (Triticum aestivum L.), two with contrasting rhizosheath-forming ability and the other four untested, were grown on two soil types (Kandosol and Vertosol) under simulated autumn-break rainfall and false-break durations. Rhizosheath size and plant establishment traits were measured.

Key results. The ability to form large rhizosheaths explained ~80% of the variability in crop establishment under various scenarios of false-break conditions. Comparative growth performance of the cultivars forming the largest (cv. Flanker) and smallest (cv. Westonia) rhizosheaths showed that they were largely similar for the first 28 days of drought but differed significantly thereafter. Flanker was progressively better able to establish as false-break duration increased and showed significantly greater tiller and leaf production than Westonia.

Conclusions. We demonstrate that genotype selection for formation of large rhizosheaths can help to reduce plant seedling death under false-break conditions.

Implications. Although the amount of starting rainfall is critical, cultivars differ significantly with regard to how far they can develop without follow-up rain. Future research is suggested for a field-scale study of the potential for selection for larger rhizosheaths to improve wheat crop establishment under harsh conditions.

Context. Limitation in soil organic matter interferes with plant growth and productivity. Chemical fertilisers can provide limiting nutrients to plants, especially in barren soil, but they have detrimental effects on living organisms; therefore, plant growth-promoting (PGP) rhizobacteria may be an alternative to synthetic fertilisers to improve plant tolerance to nutrient stress.

Aims. This study evaluated the effects of single and co-inoculation of two PGP rhizobacterial strains with macroalgae (Cladophora glomerata) extract on barley growth. We also tested the ability of the respective strains to produce biofilm and exopolysaccharide (EPS) at different pH values under in vitro conditions.

Methods. Plants were cultivated in an organic matter-limited alkaline soil under field conditions.

Key results. All treatments increased barley growth parameters to some extent. Growth parameters increased most in Bacillus + macroalgae extract (B + MA) and Bacillus + Azotobacter + macroalgae extract (B + A + MA) treatments. These two treatments significantly enhanced shoot length by 22.9–25.7%, dry weight of shoot + spike by 118.2–154.5%, total weight of grains by 76.5–78.1%, and number of grains per spike by 94.8–112.1% in comparison with the control. The respective two treatments also increased biofilm formation and EPS production in response to alkaline pH.

Conclusions. Barley productivity may be increased by using PGP strains with greater potential to produce biofilm and EPS, and inoculating them with macroalgae extract. The B + MA treatment could be applied singly or in combination with Azotobacter.

Implications. Single or co-inoculation of such PGP bacteria with macroalgae extract may be commercialised to enhance barley productivity in organic matter-limited soils.

Context. Researchers have been accumulating information concerning the locations of genes and quantitative trait loci (QTLs) in cultivated oat (Avena sativa L.) for more than 100 years.

Aims. The aim of this work was to create an inventory of genes and QTLs found in cultivated hexaploid oat and produce tools to make this resource more useful.

Methods. By using the positions of perfectly matched, single nucleotide polymorphism markers, each centimorgan (cM) location along the consensus map was assigned to a location on the OT3098 v2 physical map found on the GrainGenes database website ( https://wheat.pw.usda.gov/jb/?data=/ggds/oat-ot3098v2-pepsico). This information was then used to assign physical locations to the genes and QTLs in the inventory, where possible.

Key results. A table comparing the major genetic maps of hexaploid oats to each other, to the 2018 oat consensus map, and to physical chromosomes was produced. Genome browser tracks aligning the consensus map regions and the locations of the genes and QTLs to OT3098 v2 were added to GrainGenes.

Conclusions. Many oat genes and QTLs identified using genetic mapping could be assigned positions on physical oat chromosomes. However, many of these assigned regions are quite long, owing to the presence of large areas of reduced recombination. Specific examples of identified patterns of recombination between the genetic and physical maps and validated gene and QTL locations are discussed.

Implications. These resources will assist researchers performing comparative genetic and physical mapping in oat.

Context. Root symbionts affect forage production by influencing host plant growth, but their specific effects on canopy intercepted photosynthetically active radiation (IPAR) and its conversion to plant biomass have not been investigated.

Aims. We evaluated the extent to which changes in plant biomass resulting from arbuscular mycorrhizal fungi (AMF) and rhizobia can be explained by alterations in IPAR and aboveground and total radiation-use efficiency (RUE: the ratio between shoot or total biomass and IPAR).

Methods. Under controlled greenhouse conditions, we evaluated single and dual inoculation effects of AMF and rhizobia on the forage legume white clover (Trifolium repens L.). Experimental units comprised canopies created in trays (50 cm by 34 cm by 13 cm deep).

Key results. On average, AMF inoculation increased IPAR by 43%, owing to greater leaf area and density, and decreased total RUE by 30%. Aboveground RUE was lower in AMF-inoculated plants without rhizobial inoculation, despite their higher leaf phosphorus status and greenness during the vegetative and reproductive stages, respectively. Rhizobial inoculation reduced the negative effect of AMF inoculation on aboveground RUE.

Conclusions. Both AMF and rhizobia alter white clover structure and function at canopy level. These variations may not be detected if the analysis considers only the impact of root symbionts on plant biomass.

Implications. These findings offer valuable insights into the intricate interactions between root symbionts and canopy-level processes, providing a basis for further research at agricultural scale.