Lodging is the permanent displacement of plant shoots from an upright position and represents a major obstacle to reaching yield potential in bread wheat (Triticum aestivum L.). Breeding programs would benefit from the identification of lodging-related traits amenable to easy and rapid screening, even in the absence of lodging. However, no locally tested lodging model is available for the Pampas region of Argentina, and most lodging models are based on measurements before crop maturity. We adapted two existing models and generated a new one, using easily measurable traits at crop maturity in 24 cultivars (14 for model fit and 10 for model validation) grown in plot trials with no nutritional, water or disease restrictions in three crop seasons at Balcarce, Argentina. Of 17 traits evaluated, 16 showed differences between cultivars (P < 0.05), and in 11 of these traits, no genotype × environment interaction was detected (P > 0.05). Estimations of the safety factor against stem lodging, proposed by Crook et al., and the wind velocity that produces lodging, proposed by Berry et al., showed a high correlation with lodging score (R² = 0.60 and 0.72, respectively), but when the estimators were tested with another set of cultivars there was no association. A new empirical regression model was based on three traits measured at maturity: plant height, spike dry weight, and the inertia moment of the stem base (stem resistance to bending estimated from stem diameter and wall thickness). The model was then simplified by replacing the third trait with basal stem diameter, and it showed an even better fit (R² = 0.90). These models were satisfactorily validated by rank correlations with a different cultivar set. The regression model proposed in this study can easily be applied to the evaluation of commercial cultivars and may be used to screen breeding materials. Measurements at maturity are convenient and easy to combine with other traits of possible selective advantage.

Karnal bunt is a seedborne disease of wheat caused by the fungus Tilletia indica Mitra and is a major biosecurity threat for the Australian wheat industry. Host-plant resistance is an effective means of controlling this disease. This study has identified Australian wheat genotypes with durable resistance should the pathogen enter Australia and become established. These genotypes provide a basis for breeding adapted genotypes that can be recommended for growers. In the study, 196 genotypes comprising 177 common (bread) wheat (hexaploid, Triticum aestivum), eight durum (tetraploid, T. durum) and 11 triticale (× Triticosecale) genotypes were evaluated in the field for their reaction to infection by the fungus. Six experiments were carried out at CIMMYT’s research station at Obregon, Mexico, during three consecutive cropping seasons (2014–15, 2015–16 and 2016–17) and at two planting dates. In each experiment, the genotypes were screened for resistance to Karnal bunt by injecting an inoculum suspension with a hypodermic syringe into the boot at awn emergence. Disease incidence averaged 14.7% infection in 2015, 21.7% in 2016 and 25.6% in 2017. Resistant triticale genotypes, Tuckerbox, Berkshire and Hawkeye, were identified, along with three resistant wheat genotypes, Batavia, Pelsart and RAC-655, and two moderately resistant durum genotypes, Hyperno and Saintly. Stability analysis showed that RAC-655, Hyperno, Tuckerbox and Berkshire were consistently resistant to infection in different seasonal conditions and unaffected by the environment.

Low temperature, particularly during the reproductive stage in rice (Oryza sativa L.), leads to reduced fertility and yield and is a major constraint faced in temperate rice ecology. The floral trait anther dehiscence length has not been quantified in relation to low-temperature tolerance in rice. Two controlled-temperature glasshouse experiments evaluated 120 genotypes from BC₁F₆ recombinant inbred lines when exposed to low air temperature at the booting (young microspore) and flowering stages.

Soybean (Glycine max (L.) Merrill) germplasm in Southern China is extremely diverse. In order to explore the differentiation and evolution among geographic sowing-seasonal ecotypes of the Southern China Soybean Germplasm Population (SCSGP), we tested a sample set of accessions comprising 359 of the spring-sowing (SP) ecotype and 341 of the summer–autumn-sowing (SA) ecotype for their flowering date and sensitivity to seasonal photo-thermal changes in Nanning, Guangxi, China. The sample set and another 175 wild annual accessions were genotyped with 60 representative simple sequence repeat (SSR) markers. The SCSGP is characterised by its geographic differentiation (four geo-regional ecotypes), especially its sowing-seasonal differentiation (SA and SP ecotypes), and their combinations (eight geo-seasonal eco-populations). The ecological differentiation coincided with genetic differentiation in terms of allele richness and genetic distance. Neighbour-joining clustering among accessions by using SSRs indicated SA varieties to be the primitive ecotype relative to SP. The SA ecotype of Eco-region III (SA-III) was the most primitive among the eight geo-seasonal eco-populations, from which evolved SA-IV, and then SA-VI and SA-V. The SP ecotype was mainly evolved from its older SA counterpart, starting from SP-III emerging from SA-III accompanied by its introduction to Eco-region IV and other boarder regions. The evolutionary relationship among the geo-seasonal eco-populations was validated further with the analysis of multi-population specific-present alleles, which supports the hypothesis of Southern China origin of cultivated soybeans.

Chemical compounds in soybean (Glycine max (L.) Merr.) seed have great effects on the flavour and taste of soymilk. The 1-octen-3-ol content in soybean seed could produce sensory off-flavours (mushrooms, lavender, rose and hay flavour) during the processing of soymilk. The most effective way to reduce off-flavours of soymilk is the screening and utilisation of soybean cultivars with reduced 1-octen-3-ol content. However, genomic study of 1-octen-3-ol in soybean has not previously been reported. In the present work, a natural population of 90 diverse soybean accessions was used to dissect the genetic basis of 1-octen-3-ol content in soybean seed through genome-wide association analysis by using 26 822 single nucleotide polymorphisms (SNPs). Twenty-one novel quantitative trait nucleotides (QTNs) were thus identified to be associated with 1-octen-3-ol content in soybean seed. Among them, 13 QTNs overlapped with, or were located in, the linked regions of known QTNs for protein, oil and/or fatty acid content in soybean seed. The functional genes located in the 200-kb genomic region of each peak SNP were considered possible candidates related to 1-octen-3-ol, such as genes involved in amino acid metabolism, protein content, and hormone metabolism. The identified loci with beneficial alleles and the candidate genes may be valuable for improving the off-flavours of soymilk.

Annual ryegrass (ARG) (Lolium rigidum Gaudin) is a problematic weed for chickpea (Cicer arietinum L.) production in Australia. Understanding the critical period of control of ARG in chickpea is important for developing effective integrated management strategies to prevent unacceptable yield loss. Experiments were conducted over 2 years at the research farm of the University of Queensland, Gatton, to evaluate the effect of chickpea row spacing (25 and 75 cm) and cultivar (PBA Seamer and PBA HatTrick) and ARG infestation period (from 0, 3 and 6 weeks after planting (WAP), and weed-free) on ARG suppression and grain yield of chickpea. Year × treatment interactions were not significant for any parameter, and none of the treatment combinations showed any interaction for grain yield. Average grain yield was greater (20%) with 25-cm than 75-cm rows. On average, PBA Seamer had 9% higher yield than PBA HatTrick. Average grain yield was lowest in season-long weedy plots (562 kg ha^–1) and highest in weed-free plots (1849 kg ha^–1). Grain yield losses were lower when ARG emerged at 3 WAP (1679 kg ha^–1). Late-emerged ARG (3 and 6 WAP) had lower biomass (4.7–22.2 g m^–2) and number of spikes (5–24 m^–2) than ARG that emerged early; at 0 WAP, weed biomass was 282–337 g m^–2 and number of spikes 89–120 m^–2. Compared with wide row spacing, narrow row spacing suppressed ARG biomass by 16% and 52% and reduced number of spikes of ARG by 26% and 48% at 0 WAP and 3 WAP, respectively. PBA Seamer suppressed ARG growth more effectively than PBA HatTrick, but only in the season-long weedy plots. Our results imply that in ARG-infested fields, grain yield of chickpea can be increased by exploring narrow row spacing and weed-competitive cultivars. These cultural tools could be useful for developing integrated weed management tactics in chickpea in combination with pre-emergent herbicides.

Mixed farming systems have traditionally incorporated subterranean clover (Trifolium subterraneum L.) and lucerne (Medicago sativa L.) as key components of the pasture phase across south-eastern Australia. However, poor adaptation of subterranean clover to acidic soils, insufficient and inconsistent rainfall, high input costs, soil acidification and the emergence of herbicide-resistant weeds have reduced efficacy of some traditional clover species in recent years. To overcome these challenges, numerous novel pasture species have been selectively improved and released for establishment in Australia. Despite their suitability to Australian climate and soils, limited knowledge exists regarding their weed-suppressive ability in relation to establishment and regeneration. Field trials were therefore conducted over 3 years in New South Wales to evaluate the suppressive potential of selected pasture legume species and cultivars as monocultures and in mixed stands against dominant annual pasture weeds. Pasture and weed biomass varied significantly between pasture species when sown as monocultures, but mixtures of several species did not differ with regard to establishment and subsequent weed infestation. Arrowleaf clover (T. vesiculosum Savi.) and biserrula (Biserrula pelecinus L.) cv. Casbah showed improved stand establishment, with higher biomass and reduced weed infestation compared with other pasture species. Generally, weed suppression was positively correlated with pasture biomass; however, yellow serradella (Ornithopus compressus L.) cv. Santorini exhibited greater weed suppression than other pasture legumes while producing lower biomass, thereby suggesting a mechanism other than competition for resources affecting weed-suppressive ability. Over the period 2015–17, arrowleaf clover and biserrula cv. Casbah were generally the most consistent annual pasture legumes with respect to yearly regeneration and suppression of annual pasture weed species.

Crop models are important tools for assisting farmers and crop consultants to make decisions about fertilisation, irrigation and harvest management, because they allow users to understand productivity from the view of integrated sensitivities of basic plant physiological processes. The first objective of this study was to evaluate the performance of the CSM-CROPGRO-Perennial Forage model (PFM) to simulate regrowth of Urochloa brizantha (Hochst. ex A.Rich.) R.D.Webster cv. Marandu under varying irrigation and nitrogen levels. The second objective was to evaluate the water-balance module of the model under soil and climatic conditions in the Cerrado biome of central-eastern Brazil. The experimental data for model evaluation were obtained from a field experiment conducted during 2015, 2016 and 2017, and included herbage production, plant-part composition and plant nitrogen (N) concentration. The results suggest that the model can be used to simulate growth of Marandu palisade grass adequately under different managements of irrigation and N fertilisation. The findings indicate also that the agreement between simulations and field-observed soil moisture shows good performance of the water-balance module of CSM-CROPGRO-PFM. The most important parameterisation required by the model was the determination and calibration of inputs such as the stable soil carbon pool (SOM3) for N mineralisation, which affected the N response, and the soil water-holding characteristics, which affected the irrigation response. The default parameterisation (species, ecotype, cultivar) of cv. Marandu in CSM-CROPGRO-PFM was sufficient for adequate performance of the model for this new environment and new crop management. However, minor modifications of species parameters were helpful to account for winter-kill of foliage.

The profitability of dairying in south-eastern Australia can be improved by increasing pasture production during summer–autumn, when growth rates for the existing perennial ryegrass (Lolium perenne L.) feedbase are low. A study undertaken in cool-temperate north-west Tasmania examined the effect of stubble height and irrigation management on swards of perennial ryegrass, continental (summer-active) tall fescue (Festuca arundinacea Schreb.) and chicory (Cichorium intybus L.). Irrigation treatments included full irrigation (∼20 mm applied at every 20 mm precipitation deficit), deficit irrigation (∼20 mm applied at alternate full-irrigation events) and rainfed (no irrigation).

Defoliating pasture to shorter stubble heights (height above the soil surface) may increase temperature at the plant crown (plant–soil interface). This is especially relevant to summer C₃ pasture production in parts of south-eastern Australia, where above-optimal ambient temperatures (≥30°C) are often recorded. A rainfed field experiment in north-west Tasmania, Australia, quantified the effect of stubble-height management on the upper distribution of crown temperatures (90th and 75th percentiles) experienced by three pasture species: perennial ryegrass (Lolium perenne L.), tall fescue (Festuca arundinacea Schreb.; syn. Schedonorus arundinaceus (Schreb.) Dumort.; syn. L. arundinaceum (Schreb.) Darbysh.), and chicory (Cichorium intybus L.). Three stubble-height treatment levels were evaluated: 35, 55 and 115 mm. Defoliation to shorter stubble heights (35 or 55 mm cf. 115 mm) increased the crown temperature of all species in the subsequent regrowth cycle (period between successive defoliation events). In the second summer, defoliating to shorter stubble heights increased the 90th percentile of crown temperature by an average of 4.2°C for perennial ryegrass, 3.6°C for tall fescue and 1.8°C for chicory. Chicory and second-year tall fescue swards experienced less-extreme crown temperatures than perennial ryegrass. This may partly explain why these two species often outyield perennial ryegrass in hotter summer environments than north-west Tasmania, and hence the increasing interest in their use.