Late-maturity alpha-amylase (LMA) is a key concern for Australia’s wheat industry because affected grain may not meet receival standards or market specifications, resulting in significant economic losses for producers and industry. The risk of LMA incidence across Australia’s wheatbelt is not well understood; therefore, a predictive model was developed to help to characterise likely LMA incidence. Preliminary development work is presented here based on diagnostic simulations for estimating the likelihood of experiencing environmental conditions similar to a potential triggering criterion currently used to phenotype wheat lines in a semi-controlled environment. Simulation inputs included crop phenology and long-term weather data (1901–2016) for >1750 stations across Australia’s wheatbelt. Frequency estimates for the likelihood of target conditions on a yearly basis were derived from scenarios using either: (i) weather-driven sowing dates each year and three reference maturity types, mimicking traditional cropping practices; or (ii) monthly fixed sowing dates for each year. Putative-risk ‘footprint’ maps were then generated at regional shire scale to highlight regions with a low (<33%), moderate (33–66%) or high (>66%) likelihood of experiencing temperatures similar to a cool-shock regime occurring in the field. Results suggested low risks for wheat regions across Queensland and relatively low risks for most regions across New South Wales, except for earlier planting with quick-maturing varieties. However, for fixed sowing dates of 1 May and 1 June and varying maturity types, the combined footprints for moderate-risk and high-risk categories ranged from 34% to 99% of the broad wheat region for South Australia, from 12% to 97% for Victoria, and from 9% to 59% for Western Australia. A further research component aims to conduct a field validation to improve quantification of the range of LMA triggering conditions; this would improve the predictive LMA framework and could assist industry with future decision-making based on a quantifiable LMA field risk.

Lodging in plants is an important constraint that leads to yield losses and cause problems with mechanical harvesting. This research was aimed at determining the effects of foliar application of uniconazole or ethephon on lignin metabolism, characteristics of second basal internode and their relationship with lodging resistance in winter wheat (Triticum aestivum L.). In separate experiments, uniconazole was sprayed on the foliage at concentrations of 0, 15, 30 and 45 mg L^–1, and ethephon at concentrations of 0, 50, 75 and 100 mg L^–1 at the four-leaf stage. Foliar application of uniconazole or ethephon significantly reduced the lodging rate by increasing the lignin content and optimising basal-internode characteristics. Lignin content was significantly positively correlated with breaking strength, and negatively correlated with lodging rate, whereby the higher lignin content in the second basal internode significantly improved the lodging resistance and reduced the lodging rate in the wheat crop. Foliar application of uniconazole or ethephon also increased the breaking strength, internode diameter, wall thickness and internode plumpness of the second basal internode; maximum values were obtained with uniconazole at 30 mg L^–1 and with ethephon at 75 mg L^–1. Grain yield, lignin content and lignin-related enzyme activities of phenylalanine ammonia-lyase, tyrosine ammonia-lyase, cinnamyl alcohol dehydrogenase and peroxidase were all significantly improved with the foliar application of uniconazole or ethephon. These results suggest that lignin content in the second basal internode in wheat was closely related with lodging resistance. Foliar application of uniconazole or ethephon at the four-leaf stage reduced the lodging rate, and the concentration showing the greatest effects was 30 mg L^–1 for uniconazole or 75 mg L^–1 for ethephon.

Soil organic matter (SOM) in agricultural soils is generally lower in cultivated and intensively managed cropping soils than in pasture soils. Cultivation during the transition from pasture to crop leads to a loss of SOM, which may affect soil functionality and subsequent agricultural productivity. However, it is unclear how management practices influence SOM dynamics following this transition. We investigated the impact of initial soil fertility and application of lime and nutrients (nitrogen (N), phosphorus (P) and sulfur (S)) on changes in soil carbon (C) during the transition from a permanent pasture to a crop. The pasture was managed over 20 years with fertiliser to generate soils with initial high and low fertility (referred to as P2 and P0, respectively), based on soil C, N, P and S concentrations. Prior to sowing, pasture residue was incorporated with three treatments applied: control, lime, and lime + nutrient. Two successive crops of triticale (Triticale (× Triticosecale)) were then grown. The P0 and P2 soils were again cultivated in March 2018 with incorporation of the triticale stubble residue (9 Mg ha^–1) in each of the three soil treatments. After the two successive cereal crops, higher whole-soil C stocks were retained in the P2 than the P0 soils (difference of 2.1 Mg C ha^–1 compared with an initial difference in stocks of 2.4 Mg C ha^–1), with smaller loss of whole-soil C in P2 soils receiving the lime and lime + nutrient treatments than in the P2 control (average 10.3%, 10.0% and 20.2% loss of total C, respectively, relative to initial levels of soil C). Loss of C from the more active >0.4-mm fraction as a proportion of total C loss was higher in the first year with incorporation of legume-based pasture residue than in the second year with incorporation of C-rich, nutrient-poor crop residue (56% and 18% of the loss of C from the whole soil was from the >0.4-mm fraction in the first and second year, respectively). In P2 soil, loss of C was smaller in the more stable <0.4-mm fraction in the lime and lime + nutrient treatments than in the control (average loss of 9.6%, 11.2% and 17.6%, respectively). By contrast, in the low-fertility (P0) soil, loss of C was greater in the <0.4-mm fraction in the lime treatment than in the control (12.3% and 3.4% loss, respectively) unless supplementary nutrients were added at the time of cultivation (7.0% loss). Narrowing of nutrient ratios (C : N and C : S) in the P0 whole soil over time suggested that the loss of soil C was associated with increased microbial processing of C in the coarse-fraction soil. Taken together, the results demonstrate that loss of C from the pasture soils after cultivation was lower for soil with initially higher soil fertility when lime was applied, and that for soils with lower initial fertility, application of nutrients in addition to those for crop growth reduced C mineralisation induced by lime application.

Many agricultural soils are naturally acidic, and agricultural production can acidify soil through processes such as nitrogen (N) fixation by legumes and application of N fertiliser. This means that decisions about mitigation of soil acidity (e.g. through application of lime), crop rotation and N fertiliser application are interdependent. This paper presents a dynamic model to determine jointly the optimal lime application strategies and N application rates in a rainfed cropping system in Western Australia. The model accounts for two crop rotations (with and without a legume break crop), for the acid tolerance of different crop types, and for differences in the acidifying effect of different N fertilisers. Results show that liming is a profitable strategy to treat acidic soils in the study region, but that there are interactions between N and acidity management. Choice of fertiliser affects optimal lime rates substantially, with the use of a more acidifying ammonium-based fertiliser leading to higher lime rates. The optimal liming strategy is also sensitive to inclusion of a legume crop in the rotation, because its fixed N can be less acidifying than fertiliser, and it allows a reduction in fertiliser rates. Higher rainfall zones have greater N leaching, which contributes to a higher optimal rate of lime. We find that injection of lime into the subsoil increases profit. Optimal lime rates in the absence of subsoil incorporation are higher than usual current practice, although the economic gains from increasing rates are small.

The TIR (Toll/interleukin-1 receptor) domain has been proposed to play a signalling role in resistance responses mediated by TIR-containing proteins. The functions of some TIR-domain-containing proteins have been defined in some plants; however, there has been no study evaluating TIR-domain-containing proteins in soybean (Glycine max (L.) Merr.). In this study, GmTIR was isolated from soybean, and its functions under stresses were analysed. Analysis of tissue-specific expression patterns showed that GmTIR was strongly expressed in leaves and weakly expressed in the immature green beans. Treatments with Phytophthora sojae, salicylic acid, methyl jasmonate, abscisic acid, copper, salt and drought significantly increased GmTIR expression, and 1-aminocyclopropane-1-carboxylic acid and low temperature caused slight increases. Compared with wild type expression, GmTIR overexpression in Arabidopsis thaliana led to a higher germination rate under both salt and drought stresses, but the root length of transgenic Arabidopsis was greater than of wild type plants only under salt stress. In response to the stresses, accumulation of proline in transgenic plants was also higher. The results suggest that GmTIR could be a positive factor for promoting the survival of plants under biotic and abiotic stresses.

Limited information is available on accumulation, distribution, and remobilisation of dry matter (DM) and nutrients in cotton (Gossypium hirsutum L.) under the interaction of nutrient management and genotype. We conducted a 2-year field experiment to study the impacts of phosphorus (P) treatments (0, 16.5, 33, 66, 132 and 198 kg P ha^–1) on growth and P absorption, allocation and remobilisation in three cotton genotypes. At maturity, the maximum DM and P content allocation to seeds were 20.7% and 62.3%, respectively. Compared with the anthesis stage, leaf DM and P content at maturity significantly decreased by 46.3% and 73.6%, respectively; thus, seed P content was mainly contributed by leaves. Compared with the control (nil P), optimal P fertilisation (33–66 kg P ha^–1) increased leaf DM and P content at anthesis by 21.2% and 40.8%, promoted P translocation from leaves to seeds by 43%, and improved lint yield at maturity by 22.8%. At anthesis and maturity, the DM and P content of the entire plant, and lint and seed yields were higher in genotypes XLZ57 and XLZ19 than in XLZ13. Suitable P doses increase DM and P accumulation and yield, and improve source–sink relationships of DM and P in cotton.

The seasonal pattern of pasture production and its variability from year to year are important for pasture-based livestock production systems in south-eastern Australia because they influence key strategic decisions such as stocking rate and timing of the reproductive cycle. In this study, the effects of observed climate variations over the period 1960–2015 on pasture growth patterns were investigated by using a biophysical modelling approach. Pasture growth rates were simulated using DairyMod biophysical software at five sites ranging from high-rainfall, cool temperate at Elliott in Tasmania to medium-rainfall, warm temperate at Wagga Wagga in southern New South Wales. Annual pasture yields showed a small increasing rate of 50 kg DM/ha.year at Elliott and 40 kg DM/ha.year at Ellinbank (P < 0.05), whereas other sites showed no significant trend over time. A cross-site analysis of seasonal average pasture growth rates predicted under four different discrete periods of 14 years each showed that winter growth has increased steadily through time (P = 0.001), and spring pasture growth rate has decreased (P < 0.001) in 2002–15 compared with the earlier periods. Year-to-year pasture yield variability (coefficient of variation) during autumn and spring seasons has also increased (P < 0.05) across sites in the period 2002–15 compared with 1998–2001. At each site, the number of spring days with water stress (growth limiting factor_water <0.7) was ∼10 times greater than the number of days with temperature stress (growth limiting factor_temperature <0.7). There was an increase in the number of days with water stress at Wagga Wagga, and increased heat stress at Wagga Wagga and Hamilton (P < 0.05) in the most recent period. These results highlight the importance of incorporating more heat-tolerant and deep-rooting cultivars into pasture-based production system. Although previous studies of climate-change impact have predicted increasing winter growth rates and a contraction of the spring growing season in the future (2030), this study provides clear evidence that these changes are already occurring under the observed climate in south-eastern Australia.

Ineffective management of pastures still constitutes the main problem in the Brazilian livestock industry, in which recovery of soil fertility is a determinant for soil restoration. In this context and in combination with the adoption of sustainable technologies, the use of plant-growth-promoting bacteria (PGPB) may represent an alternative to the use of chemical fertilisers that would reduce costs and environmental impacts. In this study, morphogenetic and structural characteristics were evaluated in three Urochloa (syn. Brachiaria) varieties. Urochloa is a genus that is present in the most degraded pastures in Brazil. The three varieties were inoculated with five PGPB (Azospirillum brasilense Ab-V5 and Ab-V6, Pseudomonas fluorescens CCTB 03 and ET76, and Pantoea ananatis AMG521) and treated with different doses of nitrogen (N) fertiliser (0, 50 and 100 kg N ha^–1) in pots filled with sandy soil under greenhouse conditions. In general, for Marandu grass U. brizantha cvv. BRS Paiaguás and Xaraés, the best performances for leaf and stem elongation rates and number of basal tillers were obtained with strains CCTB 03 and AMG521. For U. ruziziensis, the best performance in the duration and rate of renewal of leaves and leaf senescence was observed with strains AMG521, Ab-V5 and Ab-V6. This result indicated the specificity of the effects of bacterial strains on different genotypes of Urochloa. Differences in the interactions between PGPB and N fertilisation were also verified. In U. brizantha, interaction effects were additive, whereas in U. ruziziensis, they were competitive. The results indicate the feasibility of inoculation of Urochloa with elite strains of PGPB that positively affect the production of forage biomass and allow reductions in N fertiliser usage.

Lucerne (alfalfa, Medicago sativa L.) is grown extensively worldwide owing to its high forage biomass production and nutritional value. Although this crop is characterised as being tolerant to drought, its production and persistence are affected by water stress. Selection of genotypes of high yield potential and persistence after a long period of drought is a major objective for lucerne-breeding programmes in Mediterranean environments. This selection could be enhanced and accelerated by the use of physiological and productivity traits and their estimation through remote-sensing methods. A set of nine cultivars of lucerne from Australia and the USA were assessed in four locations in Mediterranean central-south Chile. Several physiological and productivity traits were evaluated: forage yield (FY), stomatal conductance (gs), water potential (WP), leaf area index (LAI), nitrogen (N) content, and isotope composition (δ¹³C and δ¹⁸O) of the dry matter. Spectral-reflectance data were used to estimate the traits through spectral-reflectance indices (SRIs) and multivariate regression methods. For the SRI-based estimations, the R² values for each assessment were <0.65. However, traits such as LAI, WP, gs, and N content showed higher R² values when data from the different assessments were combined. Regression-based estimation showed prediction power similar to or higher than the SRI-based approaches. The highest R² value was for δ¹³C (0.78), but for most traits the combination of data from different assessments led to higher trait estimation, with respective R² values for LAI, FY, WP and gs of 0.67, 0.71, 0.63 and 0.85. Among regression methods, the best estimation was achieved by using support vector machine regression. The use of spectral-reflectance data collected at field level and multivariate regression models has great potential to estimate physiological and productivity traits in lucerne under water deficit and could be useful in lucerne-breeding programmes.