Fusarium wilt, caused by Fusarium oxysporum f. sp. mungcola (Fom), is an increasingly serious disease of mungbean (Vigna radiata (L.) R.Wilczek) in China. Pathogenic variability has been observed among Fom isolates; however, there are no reports describing Fom races or pathotypes. Thus, this study was conducted with the aim of developing a set of pathotype differentials to reveal Fom pathotype diversity by assessing virulence variability of Fom isolates. First, 105 mungbean cultivars were screened against a standard virulent Fom isolate (F08). Eleven of the 105 cultivars were selected as candidate differentials of Fom according to resistance phenotype and genetic background. Second, the resistance of the 11 candidate differential cultivars was tested against 30 Fom isolates from different geographical origins in China. Highly significant differences were observed among isolate × cultivar interaction patterns, indicating that pathotype differentiation exists in Fom isolates. Based on the different reaction patterns combining with genetic background, seven of the 11 cultivars were selected to constitute a set of differential hosts of Fom pathotype, used to distinguish pathotypes of 84 Fom isolates from different geographical regions by evaluating the virulence reaction pattern. The results showed that the 84 Fom isolates were defined as 12 pathotypes. Finally, we tried to confirm whether the 12 Fom pathotypes could be distinguished by a PCR-based diagnostic method based on the two genes (SIX6 and SIX11) reported to be associated with Fom pathogenicity. However, the Fom pathotype could not be distinguished by variation of the PCR products or their resulting sequences of the two genes. This is the first study to develop a set of Fom pathotype differential hosts and identify 12 Fom pathotypes, which provides important information for resistance breeding and disease control.

Association analysis is an alternative to conventional, family-based methods for detecting the location of gene(s) or quantitative trait loci (QTLs), and provides relatively high resolution in terms of defining the genome position of a gene or QTL. Flavour is an essential quality characteristic of soymilk; however, soymilk contains volatile compounds unacceptable to consumers. One of main constituents in the volatiles of normal soymilk is 2-heptenal, which is thought to be a degradative oxidation product of polyunsaturated acids. In this study, a genome-wide association study using 24 651 single-nucleotide polymorphisms (SNPs) was performed to identify quantitative trait nucleotides (QTNs) controlling 2-heptenal content in soybean (Glycine max (L.) Merr.) seed from a natural population of 110 soybean germplasm accessions. We detected 62 significant QTNs located on 18 different chromosomes that are significantly associated with 2-heptenal content in soybean seed. Among these, 17 QTNs co-localised with QTLs previously found to be related to protein, oil and/or fatty acid content in soybean seed. We also identified some candidate genes involved in lipid metabolism. These findings further our understanding of the genetic basis of 2-heptenal content in soybean seed and the improvement of marker-assisted breeding efficiency, which will be important for breeding soybean cultivars with low 2-heptenal content.

Soil testing guidelines for sulfur (S) under dryland cropping in south-eastern Australia are not well developed. Our objective was to assess the value of soil and tissue tests for S and nitrogen (N), because the two minerals frequently interact), in predicting S-deficient sites and hence increasing the probability of response to application of S (and N). Here, we report three proximal experiments in 2014–16 for barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) on a sandy soil in a semi-arid environment near Merriwagga in western New South Wales. The trials contained a factorial combination of four rates of each of applied N as urea and S as high-grade gypsum.

Responses to S were obtained for dry matter (DM) quantity and nutrient content at flowering in 2014, but no grain-yield response was obtained in any year. DM response to applied S was obtained when the concentration of S in the DM was increased from 0.08% in barley and 0.09% in wheat without S application to 0.10–0.11% in both crops with S applied as gypsum. Because we obtained no grain-yield responses to applied S, the 0.10% S in grain was likely to have been adequate for both crops in these experiments. A pool of subsoil S was accessed during each season and this compensated for any DM deficiencies of S by the time of grainfill. Shallow soil tests (0–10 cm) for S can therefore indicate sufficiency but not necessarily deficiency; therefore, in grain-cropping areas, we recommend soil S tests on the same samples as used for deep N testing (to 60 cm) and that an S-budgeting approach be used following the soil tests. Furthermore, for marginal nutritional circumstances such as occurred in this study, the supporting use of N : S ratio is recommended, with values >17 in DM or grain likely to indicate S deficiency for both barley and wheat.

Phosphorus (P) is the main limiting factor for forage production in grasslands. It is important to determine levels of available P in soil that optimise production with minimum impact on arbuscular mycorrhizal (AM) symbiosis. We investigated the effects of increasing P availability on biomass production, root morphology, AM symbiosis and P acquisition of a forage legume (Lotus tenuis), a C₃ grass (Schedonorus arundinaceus) and a C₄ grass (Panicum coloratum) growing on a P-deficient soil in pots with P applied at rates of 0–160 mg kg^–1 dry soil. The three forage species responded strongly to addition of P, with 90% of maximum shoot growth reached at available P levels of 24.3 mg kg^–1 for L. tenuis, 14.4 mg kg^–1 for P. coloratum and 11.2 mg kg^–1 for S. arundinaceus. Lotus tenuis and P. coloratum produced higher yields of shoot biomass than S. arundinaceus. Root dry weight was higher in the legume than in the grasses, with the root-mass fraction being lowest in P. coloratum. AM colonisation was higher in L. tenuis roots than in grass roots, and decreased with increased soil P availability, especially in grasses. Low to moderate additions of P did not affect, and could even improve, AM colonisation in L. tenuis roots. For L. tenuis, it is possible to increase forage yield while maintaining high values of AM colonisation at 10–20 mg kg^–1 of available P, but for grasses, especially S. arundinaceus, it is difficult to achieve both objectives. The presence of L. tenuis in grasslands or pastures may contribute to maintaining the native AM inoculum under a wide range of soil P availability in regions such as the Salado River basin of Argentina.

Windmill grass (Chloris truncata R.Br.) and feathertop Rhodes grass (Chloris virgata Sw.) are two weeds of the northern region of Australia that are rapidly expanding in range, being favoured by conservation agricultural systems and prevailing weed management using a narrow pool of herbicides. Information on competitiveness and seed-production dynamics of these weeds is lacking for mungbean (Vigna radiata (L.) Wilczek), a major summer crop in the region. Field studies were conducted to evaluate the effect of different densities of these weed species on crop yield of mungbean in the 2016–17 (2016) and 2017–18 (2017) seasons. Windmill grass reduced mungbean yields by 56% with 39 weed plants m^–2 in 2016 and 55% with 47 weed plants m^–2 in 2017. Windmill grass produced a maximum of 98 708 seeds m^–2 in 2016 and 118 613 seeds m^–2 in 2017, and there was 15–21% seed dispersal at crop harvest. Competition from feathertop Rhodes grass resulted in yield losses of 73% with 49 weed plants m^–2 and 65% with 45 weed plants m^–2. Feathertop Rhodes grass produced a maximum of 229 514 seeds m^–2 in 2016 and 367 190 seeds m^–2 in 2017, and seed dispersal at crop harvest was only 3–7%. Competition from both weed species resulted in a significant reduction in number of pods per m², grains per pod and 1000-grain weight of mungbean. These results show that windmill grass and feathertop Rhodes are highly competitive against mungbean, and their timely management is crucial for minimising yield loss. Although both weeds produced a substantial number of seeds, seed dispersal at crop harvest was low, especially for feathertop Rhodes grass. The high weed-seed retention relative to maturity of mungbean may help in managing these problematic weeds through various means including weed-seed capturing and destruction

Forage brassicas are currently widely used in temperate–humid livestock systems; however, they offer potential to diversify crop rotation and forage options in the drier, mixed crop–livestock zone of Australia. A literature review highlighted that in these hotter and more arid environments, forage brassicas are more likely to fit as autumn-sown forage crop where they offer an energy-rich, highly digestible feed source that could be used during periods of low production and nutritive value of other forage sources. However, brassicas can also accumulate several anti-nutritional compounds that require gradual introduction to livestock diets, thereby reducing potential health risks and optimising animal performance. Preliminary experimental and commercial evaluations in subtropical Australia found high production of some forage brassica genotypes (>5 t DM/ha with growth rates of 50–60 kg DM/ha.day), comparable or superior to widely used forage cereal or forage legume options. Several forage brassicas showed moderate to high resistance to the root-lesion nematode, Pratylenchus thornei, and hence are likely to provide break-crop benefits compared with susceptible species (e.g. wheat). Together, this evidence suggests that forage brassicas have significant potential for wider use in crop–livestock farming systems in Australia. However, research is needed to identify genotypic adaptation and to match different forage brassica genotypes to production environments or system niches, especially some of the new genotypes that are now available. There is also a need to develop regionally-relevant recommendations of agronomic and grazing management that optimise forage and animal production, and mitigate potential animal health risks.