Echinochloa colona and E. crus-galli are two important annual grass weeds distributed throughout the summer cropping regions of Australia. Both species are highly problematic weeds, responsible for yield losses of up to 50% in summer grain crops. The success of Echinochloa species as weeds is attributed to their rapid growth, prolific seed production, seed dormancy and adaptability to a wide range of environments. Importantly, E. colona has evolved resistance to glyphosate in Australia, with resistant populations now widespread across the summer cropping regions. Fallow management of E. colona with glyphosate alone is risky in terms of increasing the chance of resistance and highly unsustainable; other control strategies (residual herbicides, strategic tillage, etc.) should be considered to complement herbicides. This review provides a summary of current information on the biology, ecology and management of Echinochloa species. The knowledge gaps and research opportunities identified will have pragmatic implications for the management of these species in Australian grain cropping systems.

The potential impact of elevated atmospheric carbon dioxide concentration ([CO₂]) and future climate predicted for 2050 on wheat marketing grades and grain value was evaluated for Victoria, Australia. This evaluation was based on measured grain yield and quality from the Australian Grains FACE program and commercial grain delivery data from Victoria for five seasons (2009–13). Extrapolation of relationships derived from field experimentation under elevated [CO₂] to the Victorian wheat crop indicated that 34% of grain would be downgraded by one marketing grade (range 1–62% depending on season and region) because of reduced protein concentration; and that proportions of high-protein wheat grades would reduce and proportions of lower protein grades would increase, with the largest increase in the Australian Standard White (ASW1) grade. Simulation modelling with predicted 2050 [CO₂] and future climate indicated reduced wheat yields compared with 2009–13 but higher and lower grain quality depending on region. The Mallee Region was most negatively affected by climate change, with a predicted 43% yield reduction and 43% of grain downgraded by one marketing grade. Using 2016 prices, the value of Victorian wheat grain was influenced mainly by production in the different scenarios, with quality changes in different scenarios having minimal impact on grain value.

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici Erikss (Pst), is one of the most damaging diseases in common wheat (Triticum aestivum L.) globally. Breeding for genetic resistance is the most effective, economical and ecologically sustainable method to control the disease. The wheat line H922-9-12, developed from a cross between Psathyrostachys huashanica Keng and T. aestivum, was highly resistant to nine Pst races in tests at the seedling stage. To characterise and map the stripe rust resistance gene(s) in H922-9-12, segregating populations were developed by crossing H922-9-12 with the susceptible cultivar Mingxian 169. When tested with Pst race CYR34, the stripe rust resistance in H922-9-12 was shown to be controlled by a single dominant gene, provisionally designated YrH922. A linkage map was constructed with five simple sequence repeat, six expressed sequence tag (EST) and two sequence-related amplified polymorphism markers. YrH922 was located on chromosome 3BL and was 2.7 and 3.4 cM proximal to EST-STS (sequence-tagged site) markers BE517923 and BE471045, respectively. The flanking marker BE517923 in marker-assisted selection for the gene can be used to improve stripe rust resistance on breeding programs.

Rice is a staple for much of the world’s population. Increased production of good-quality rice is a necessity for global food security. Variable water supply and increasingly unpredictable weather is an ongoing challenge to the Australian rice industry, with the impact felt along the supply chain from growers to consumers. This multi-environment trial (MET) is focused on capturing the quality of milled grain produced in new growing regions beyond south-eastern Australia. Data on grain quality from 54 rice-variety trials grown between 2008 and 2017 across 10 locations and two seasons (wet and dry) spanning four Australian states and territories are included. Physical quality traits (yellowness index and whole grain yield), grain composition (apparent amylose and protein content) and eating quality traits (setback and gelatinisation temperature) were analysed. Varietal predictions for each quality trait at a range of sites provide evidence for the industry to develop strategies to deliver a consistent supply of high-quality Australian-grown rice.

Multiple field experiments and a controlled-environment temperature study were conducted to investigate soil and weather conditions responsible for herbicide phytotoxicity in lentil (Lens culinaris Medik.) from post-emergent application of metribuzin. A linear relationship was observed between plant injury (% necrosis) and metribuzin rate in all 12 environments, but in only 11 environments for anthesis dry weight and nine environments for both plant density and grain yield. Grain-yield reduction from label metribuzin rates of 135 g a.i. ha^–1 for sand and 285 g a.i. ha^–1 for clay ranged from 0% to 32% and 0% to 67%, respectively, across all environments. Principal component analysis of soil and weather factors around the time of herbicide application suggested that metribuzin-induced plant damage in lentil was due to a combination of multiple soil and weather factors. However, heavy rainfall within 10 days of herbicide application, particularly on light-textured soils or where soil moisture was low, was most strongly linked to plant damage. Experiments targeting the impact of reductions in temperature post-metribuzin application showed no effect, and of light intensities pre- and post-metribuzin application showed low effects on plant-damage measures. Because rainfall in the 10 days after application is a major determinant of metribuzin damage in winter-grown lentil in southern Australia, a higher level of selective tolerance to metribuzin than that present in commercial cultivars is needed for its safe post-emergent use. Early and late measures of plant damage will be required to assess accurately plant tolerance to post-emergent metribuzin application in lentil.

Studies were undertaken under controlled conditions into the effects of different foliage components (cotyledon, first, second and third leaf) at three plant ages (3, 5 and 7 weeks old) on development of Alternaria leaf spot disease, caused by Alternaria japonica or A. brassicae, in canola (Brassica napus cv. Thunder TT) and mustard (B. juncea cv. Dune). Alternaria japonica generally showed percentage disease index (%DI) values similar to A. brassicae across the two Brassica species, different foliage components and plant ages. %DI from either pathogen was greater in older plants than younger plants for the same foliage components in both cultivars. Field studies were then undertaken with canola to compare disease development from A. japonica and A. brassicae across different plant components (leaf, pod and stem) and the consequent adverse impact on seed yield. Alternaria japonica was more severe in terms of leaf area diseased (%LAD 62.6) and stem area diseased (%SAD 69.8) than pod area diseased (%PAD 25.5), whereas A. brassicae was more severe on leaves (%LAD 61.9) than on pods (%PAD 47.4) or stems (%SAD 41.0). Stem disease incidence was greater for A. japonica (%SDI 94.0) than for A. brassicae (%SDI 56.5), but pod disease incidence was greater for A. brassicae (%PDI 93.5) than for A. japonica (%PDI 86.1). For A. japonica, AUDPC values of leaf disease incidence (LDI, 283.5), leaf area diseased (LAD, 253.3) and leaf collapse (LCI, 149.5) resulted in a yield loss of 58.1%, similar to A. brassicae, where AUDPC values of LDI (277.8), LAD (247.2) and LCI (111.0) caused a yield loss of 59.4%. These findings explain observed acceleration of Alternaria leaf spot severity from A. japonica, as from A. brassicae, through the growing season as plants become more susceptible with increasing age, and as more susceptible, later developing leaves become abundant. For the first time, we demonstrate that under conducive field conditions for disease development, A. japonica can cause serious seed-yield losses of a magnitude similar to those occurring with A. brassicae.

Two tomato (Lycopersicum solanum) varieties, one high (YSL189) and one low (HZ903) cadmium (Cd) accumulator, were used in our experiment. We detected cadmium (Cd ion/Cd-EDTA) uptake rates in roots and the corresponding expression of the Cd transport genes IRT1, IRT2, ZIP, Nramp1, Nramp2 and Nramp3. Our data proved that both cultivars – YSL189 and HZ903 – showed higher Cd accumulation in plants and a higher Cd uptake rate in roots supplied with Cd ion than with Cd-EDTA. In roots of YSL189, the expression levels of IRT1, IRT2, ZIP, Nramp1, Nramp3 and Nramp2 (5, 10 and 20 µmol_c L^–1 Cd) treated with Cd ion were higher than those treated with Cd-EDTA, whereas in roots of HZ903, only two genes, IRT1 and Nramp1 (5, 10, 100 µmol_c L^–1 Cd), showed higher expression levels in plants treated with Cd ion than in those treated with Cd-EDTA. When the difference between the cultivars was considered, the Cd concentration in the plant and the Cd uptake rate in the roots of YSL189 were higher than those of YZ903 under the same Cd treatments (i.e. Cd ion or Cd-EDTA). The expression of IRT2 and ZIP in the roots of YSL189 was higher than that observed in HZ903 treated with all levels of ion-Cd. We attribute the higher Cd uptake rate and greater accumulation of ion-Cd compared with EDTA-Cd in YSL189 than those found in HZ903 partly to the genes that had higher expression levels. Our results indicate that the roles of transporters in the absorption of different forms of Cd vary according to plant genotype.

Sugarcane (Saccharum spp. hybrids) monoculture was amended with leguminous rotation breaks (cowpea, Vigna unguiculata; and soybean, Glycine max) and compared with growers’ practice (sweet corn, Zea mays var. saccharata rotation; and bare fallow). After incorporation of rotation-break residues, fungicidal treatments (mancozeb, mefenoxam and azoxystrobin) were applied on seed-cane pieces laid in the furrows before row closure, with the objective of determining effects of both crop rotation and fungicides on soil properties and sugarcane agronomic performance. Aboveground biomass yields of sweet corn, soybean and cowpea were 5.54, 5.17 and 4.48 t ha^–1, and carbon : nitrogen ratios of sweet corn, soybean and cowpea crop residues were 25.47, 11.92 and 11.61, respectively. Following residue incorporation, phospholipid fatty acid analyses of soil microbial communities at pre-plant and early-growth stages of sugarcane indicated significant differences in abundance of Gram-positive bacteria, actinomycetes and fungi biomarkers, whereas no differences were found in Gram-negative bacteria and arbuscular mycorrhizal fungi. At pre-planting, fungi : bacteria ratios in sweet corn and bare fallow plots were significantly higher than in cowpea or soybean rotation plots and similar to ratios at early-growth sampling. Soybean rotation produced higher cane yield than sweet corn, and both soybean and bare fallow produced higher sucrose yield than sweet corn rotation in 2016 plant cane, but no significant yield differences occurred in 2017 plant cane. The results of 2016 plant cane persisted in the 2017 first ratoon, where the sweet corn rotation had lower yields than cowpea and soybean rotations. All three fungicides significantly improved cane yield and sugar yield compared with the untreated check in plant cane, with both mancozeb and mefenoxam performing similarly in 2016, but with mefenoxam performing better in 2017 plant cane. Overall, introduction of cowpea and soybean rotations, coupled with seed-piece fungicidal application, seems a promising practice for improving sugarcane yields on Histosols.

Soil salinisation and overgrazing are two important factors limiting plant growth in the Songnen Grassland, Northeast China. Leymus chinensis, a dominant rhizomatous grass, resists grazing and tolerates saline–alkali stress. However, its adaptive mechanisms to the dual effects of grazing and saline–alkali stress remain largely unknown. A two-factorial field experiment was conducted in two consecutive years in the natural L. chinensis community, combining the addition of mixed saline–alkali solution (NaCl : NaHCO₃ : Na₂CO₃ 1 : 1 : 1, amount 559.13 g m^–2 year^–1) with clipping (removal of 60% of aboveground biomass, AGB). Saline–alkali addition significantly increased AGB and total biomass in the no clipping but not in the clipping treatment. Irrespective of clipping, ramet density was significantly decreased, and individual ramet biomass was significantly increased under salt stress. The significant increase in AGB was due to a high K⁺ : Na⁺ ratio, high water-use efficiency, and an increase in leaf area index and net photosynthesis rate of individual ramets under salt–alkali stress. Clipping significantly decreased AGB and total biomass regardless of saline–alkali addition, possibly because of decreased sugar content of rhizomes. Saline–alkali and clipping had an interactive effect on AGB and total biomass of L. chinensis. The significant reduction in AGB and total biomass were mainly caused by reduced proline and water-soluble carbohydrate content under dual stress. A modified and simplified graphic model of the limiting resource model was proposed based on our results. Leymus chinensis can grow well under saline–alkali stress via ramet biomass compensation, in which the significant decrease in ramet density is compensated by the significant increase in individual ramet biomass. Ramet compensation and clonal integration were identified to be main mechanisms of herbivory and saline–alkali tolerance.

Trifolium subterraneum L. is widely grown in the phosphorus (P) deficient soils of southern Australia. However, this pasture legume has a high critical external P requirement and requires frequent applications of P fertiliser to achieve high productivity. Twenty-six genotypes of T. subterraneum were grown to determine: (i) differences in shoot growth and P acquisition under low-P supply; (ii) the root morphological traits important for P acquisition; and (iii) the feasibility of selection among genotypes for these root morphological traits. Micro-swards of each genotype were grown with a topsoil layer that was either moderately P-deficient or had P supplied in excess of the critical requirement for maximum yield; the subsoil layer was P-deficient. Yield and P content of shoots and roots were determined after 5 weeks’ growth, and root samples were assessed for diameter, length and root hair length. All genotypes were equally highly productive when excess P was supplied. However, relative shoot yield in the moderately P-deficient soil ranged from 38–71%. Total root length ranged from 63–129 m pot^–1, and was correlated with total plant P uptake (R² = 0.78, P < 0.001). Variation was also observed in average root diameter (0.29–0.36 mm) and root hair length (0.19–0.33 mm). These traits were combined with root length to calculate the total surface area of the root hair cylinder, which was also correlated with total plant P uptake (R² = 0.69, P < 0.001). The results demonstrated that there was significant variation in P acquisition efficiency and shoot yield among genotypes of T. subterraneum when grown in P-deficient soil, and that root length was important for improved P uptake. The results indicate potential to identify superior genotypes that achieve improved P acquisition and higher shoot yields in low-P soil.