FROST RESISTANCE 2 (FR2) genes of wheat are C-Repeat Binding Factor (CBF) genes with two major alleles known for both Fr-A2 (‘T’ and ‘S’) and Fr-B2 (‘WT’ and ‘DEL’). VERNALIZATION 1 (VRN1) genes have a regulatory role on CBF genes, with known epistatic interactions between Vrn-A1 and Fr-A2 for tolerance to freezing temperatures during vegetative growth. VRN1 genes were also known to affect days to heading and grain yield. Therefore, FR2 genes might also affect these traits.

A wide range of cultivars was characterised for VRN1, Fr-A2 and Fr-B2 genes. A third allele of Fr-A2 was found in cvv Excalibur and Axe. The winter cultivar Norstar, which was known to have a high level of frost tolerance during vegetative growth, had the combination Vrn-A1w   Fr-A2T   Fr-B2WT, as did a spring landrace from Afghanistan that was known to have superior tolerance to frost during reproductive development. No Australian spring cultivar was found with this combination, but it could be selected from crosses between adapted cultivars. This would enable the role of VRN1 and FR2 alleles in reproductive frost tolerance to be evaluated in an adapted background. Using large, existing, plant-breeding datasets, the T allele of Fr-A2 delayed heading relative to the S allele, and the WT allele of Fr-B2 delayed heading relative to the DEL allele, but only in combination with particular alleles of the VRN1 genes. Fr-B2 affected grain yield, with the highest grain yields for spring lines produced by Fr-B2DEL in combination with the spring allele of Vrn-B1.

The expression of nitrate and ammonium transporter genes in the roots of winter wheat in response to drought stress is largely unknown. A greenhouse experiment was established to study the expression of five putative nitrate transporter (NRT) genes (TaNRT2.1, TaNRT2.2, TaNRT2.3, TaNRT1.1, TaNRT1.2) and three ammonium transporter (AMT) genes (TaAMT1.1, TaAMT1.2, TaAMT2.1) in the roots of winter wheat in response to soil drought under conditions of limited nitrogen (N) (no N added) and adequate N (addition of 0.3 g N kg^–1 soil). Two wheat genotypes with low and high N-uptake efficiencies were used, and water-stress treatments were applied at the vegetative and reproductive growth stages of wheat. Expression of all of the genes was quantified using real-time reverse transcription PCR. The results indicated that wheat plants growing in the N-adequate soil were more sensitive to drought stress than those growing in the N-limited soil. The response of the expression of the NRT and AMT genes to soil drought largely depends on N application, wheat genotype and growth stage. The expression of the two low-affinity NRT genes (i.e. TaNRT1.1 and TaNRT1.2) in the N-inefficient genotype XY6 was mainly induced by drought stress, but the expression of the two genes in the N-efficient genotype XY107 was repressed by drought stress. The expression of the high-affinity NRT gene TaNRT2.1 was repressed by drought stress, but the expression of the other two high-affinity NRT genes, TaNRT2.2 and TaNRT2.3, was induced or repressed by soil drought depending on N application and growth stage. The expression of the genes TaAMT1.1 and TaAMT2.1 was mainly repressed by drought stress, whereas the expression of the gene TaAMT1.2 was induced by drought stress. The expression of TaNRT2.1 in XY107 was significantly higher than in XY6.

Application of film antitranspirant to wheat during late stem extension reduces drought damage to yield, but the mechanism is unknown. Field experiments under rain shelters were conducted over 3 years to test the hypothesis that film antitranspirant applied before meiosis alleviates drought-induced losses of pollen viability, grain number and yield. The film antitranspirant di-1-p-menthene was applied at third-node stage, and meiosis occurred at the early boot stage, with a range of 11–16 days after spray application in different years. Irrigated, unsprayed plots were included under the rain-shelters, and pollen viability, measured in 2 years in these plots, averaged 95.3%. Drought reduced pollen viability to 80.1% in unirrigated, unsprayed plots, but only to 88.6% in unirrigated plots treated with film antitranspirant. Grain number and yield of irrigated plots, measured in all years, were 16 529 m^–2 and 9.55 t ha^–1, respectively, on average. These were reduced by drought to 11 410 m^–2 and 6.31 t ha^–1 in unirrigated, unsprayed plots, but only to 12 878 m^–2 and 6.97 t ha^–1 in unirrigated plots treated with film antitranspirant. Thus compared with unirrigated, unsprayed plots, antitranspirant gave a grain yield benefit of 0.66 t ha^–1. Further work is needed to validate the pollen viability mechanism in different climatic zones and with a wide range of cultivars.

Predicted reduced precipitation, enhanced evaporative demand and increasing CO₂ in the atmosphere will strongly influence wheat production. The association of wheat with arbuscular mycorrhizal fungi (AMF) improves growth under stressful conditions. Our objective was to test the influence of mycorrhizal inoculation on yield, and accumulation of macro- and micro-nutrients and gliadins in grains of durum wheat (Triticum durum Desf.) plants grown under different CO₂ concentrations and water regimes. The main factors of the experimental design were mycorrhizal inoculation (inoculated or non-inoculated plants); atmospheric CO₂ concentration (ambient, ACO₂, or elevated, ECO₂); and water regime (optimal or restricted water regime). At ACO₂, the simultaneous application of AMF and water deficit decreased the number of seeds per spike without affecting the biomass of grains, and grains accumulated higher contents of copper, iron, manganese, zinc and gliadins. The opposite effect was observed with ECO₂ where, regardless of mycorrhizal and water treatment factors, a general depletion of contents of micro- and macro-nutrients and gliadins was detected. Whereas mycorrhizal inoculation together with drought applied to plants cultivated at ACO₂ improved wheat grain quality parameters, under ECO₂, mycorrhization did not ameliorate grain quality parameters detected in plants that produced the largest grain dry matter values.

Climate change is predicted to decrease crop yields in semi-arid and subtropical regions of the world and this could negatively affect smallholder farmers in the developing world. Previous analysis has suggested that with low fertiliser input, yields of sorghum increased as temperatures increased. We used the wide range of tropical environments in the small mountainous island country of Timor-Leste to evaluate the impact of global warming on maize (Zea mays) yields with (i) no fertiliser input and (ii) increased nitrogen (N) supply. We calibrated the well-tested APSIM-Maize model for the cultivar of maize grown throughout Timor-Leste. We simulated maize yields at four locations with 8 years of reliable weather records, at present temperatures, 1.5°C and 3.0°C, with 0, 40 and 80 kg/ha of added N, with 1.2, 1.9 and 3.8% soil organic carbon (SOC), and with increased duration of the vegetative phase. With no added N, higher temperatures increased yields at the cooler, higher elevation sites and decreased yields at the warmest site near the coast. With fertiliser application, warming temperatures decreased yields or induced no change in simulated yield at all locations. Simulations with three levels of N supply for the four sites, which differed in temperature, showed a strong temperature × N supply interaction on yield. At maximum growing-season temperatures >31°C, yields decreased with increasing temperature at all levels of fertilisation. At maximum growing-season temperatures of 23−31°C, yields increased with increasing temperature with no added fertiliser, were unchanged with the application of 40 kg N/ha, and decreased with increasing temperatures with application of 80 kg/ha N. The changes in yield with temperature and N supply were associated with N uptake by the maize, which showed the same interaction with maximum temperature and N added. SOC acted as a source of N, so that changes in yield induced by temperature and N were similar whether the N was from an organic or an inorganic source. Increasing the duration of the vegetative phase resulted in lower or no change in yields at all sites. We conclude that global warming will increase the yield for low-input smallholder farmers growing maize at maximum growing-season temperatures <31°C, but that micro-dosing with N will increase yields at all locations with mean maximum temperatures of 20−35°C.

Effective management strategies for nitrogen (N) fertiliser are important to ensure optimum seed yields and seed quality of canola (Brassica napus L.) crop production. A field experiment was conducted for 3 years in Ontario, Canada to determine the (i) impact of different rates and timing of application of N fertiliser on canola yield and quality; and (ii) fertiliser-N economy, including agronomic N-use efficiency (aNUE), N-uptake efficiency (NupE), N-utilisation efficiency, partial N balance and N harvest index. Treatments included factorial combinations of six (2011) or eight (2012 and 2013) rates of N as urea (46% N) and timing of application (pre-plant only or preplant plus side-dressed applications at the 6-leaf stage). Side-dressed N application resulted in significant improvements in seed yield and protein concentrations (up to 16%) over equivalent preplant-only applications. The highest seed yield (2700 kg ha^–1 in 2011 and 3500 kg ha^–1 in 2013) was produced by the treatments including side-dressing: 50   50 kg N ha^–1 or 50   100 kg N ha^–1 (preplant   side-dressing). Seed protein concentrations varied from 21% to 23% in 2011 and 2013 and up to 28% in 2012. On average, the sum of protein and oil concentrations was 65–68%. Oil yield increased with increasing N rates in 2011 and 2013, but significant increases were recorded only when N was side-dressed at the 6-leaf stage. Drought conditions in 2012 negated responses to N fertiliser regardless of when it was applied. In general, aNUE and N-utilisation efficiency were decreased with increasing N fertiliser rates, but NupE varied among environments with increasing preplant and side-dressed N application. Side-dressed N applications after preplant application resulted in higher partial N balance, aNUE and/or higher NupE than comparative preplant-only N applications. Overall, side-dressed N application led to improved crop N uptake and better N economy of canola production in eastern Canada.

In this study, the genetic diversity and relationships among eight millet genera were investigated by molecular and morphological data analyses. Sixty-nine millet accessions were analysed by using amplified fragment length polymorphism (AFLP) markers, and evaluated for morphological traits. Eight AFLP primer pairs were amplified successfully and 779 bands were scored for all accessions, with a high level of polymorphism detected. Nei’s genetic distance among all accessions varied from 0.0123 to 0.4246 and the Shannon’s index was estimated at 0.9708. The neighbour joining tree, using the unweighted neighbour-joining method and Dice’s dissimilarity coefficient, was constructed. The AFLP markers revealed the close relatedness between the Eragrostis and Panicum genera, whereas the greatest distance was found the Pennisetum and Echinochloa genera. Cluster analysis based on the AFLP profiles revealed that the majority of accessions of a given millet genus tend to group together. Clustering from morphological data allocated individuals into three main clusters with high variation. The genetic variability found between the analysed accessions was weakly negatively correlated (r = –0.074) with their morphological attributes. However, high molecular and morphological variability indicated that this collection includes rich and valuable plant materials for millet breeding.

Sweet sorghum (Sorghum bicolor L. Moench) is a promising crop for biofuel and forage production, having strong resilience to multiple stresses and being capable of thriving on marginal land. The main goals in sweet sorghum improvement are to increase biomass and sugar yield. We validated quantitative trait loci (QTLs) controlling plant height, biomass, juice weight and Brix with 181 recombinant inbred lines derived from a cross between Shihong137, a dwarf grain sorghum, and L-Tian, a tall sweet sorghum, under four environments. Seven QTLs for plant height, stem and leaf fresh weight, stem fresh weight and juice weight could be repeatedly identified across four environments. However, three of those major QTLs, qPH7-2, qSLFW9 and qSFW9, had strong epistatic effect. Many QTLs related to biomass production were co-localised with previously known height QTLs, suggesting that plant height is a major trait regulating biomass production. However, qSFW1-2, qSLFW6-1, and qSLFW6-2 were mapped to positions with no known height QTL. We also identified and validated stable qBrix2 across environments. This study provided a genetic basis for integrated approaches, including plant height, to improve sweet sorghum biomass and sugar production.

The environment is the largest component of the phenotypic variance of crop yield, hence the importance of its quantitative characterisation. Many studies focussed on the patterns of water deficit for specific crops and regions, but concurrent water and thermal characterisations have not been reported. To quantify the types, spatial patterns, frequency and distribution of both water stress and thermal regimes for chickpea in Australia, we combined trial and modelled data. Data from National Variety Trials including sowing time, yield and weather from 295 production environments were entered into simulations. Associations between actual yield, in a range from 0.2 to 5.2 t/ha, actual temperature and modelled crop water stress were explored. Yield correlated positively with minimum temperature in the 800 degree-days window bracketing flowering and the correlation shifted to negative after flowering. A negative correlation between maximum temperature over 30°C and yield was found from flowering through to 1000 degree-days after flowering. Yield was negatively correlated with simulated water stress from flowering until 800 degree-days after flowering.

Cluster analysis from 3905 environments (71 locations × 55 years between 1958 and 2013) identified three dominant patterns for both maximum and minimum temperature accounting for 77% and 61% of the overall variation, and four dominant patterns for water stress accounting for 87% of total variation. The most frequent environments for minimum and maximum temperature were associated with low actual yield (1.5–1.8 t/ha) whereas the most frequent water-stress environment was associated with the second lowest actual yield (1.75 t/ha). For all temperature and water-stress types, we found significant spatial variation that is relevant to the allocation of effort in breeding programs.

Ascochyta blight is an important disease of faba bean (Vicia faba L.). Yield losses can be as high as 90% and losses of 35–40% are common. The line 29H is one of the most resistant accessions to the pathogen (Ascochyta fabae Speg.) ever described. In this work, we aimed to validate across generations the main quantitative trait loci (QTLs) for ascochyta blight resistance identified in the cross 29H × Vf136 and to test their stability under field conditions. QTLs located on chromosomes II and III have been consistently identified in the recombinant inbred line (RIL) population of this cross, in both controlled (growth chamber) and field conditions and, thus they are good targets for breeding. In addition, a new QTL for disease severity on pods has been located on chromosome VI, but in this case, further validation is still required.

A synteny-based approach was used to compare our results with previous QTL works dealing with this pathogen. Our results suggest that the QTL located on chromosome II, named Af2, is the same one reported by other researchers, although it is likely that the donors of resistance differ in the allele conferring the resistance. By contrast, the location of Af3 on chromosome III does not overlap with the position of Af1 reported by other authors, suggesting that Af3 may be an additional source of resistance to ascochyta blight.

Cultivar mixtures of perennial ryegrass (Lolium perenne L.), which mostly contain both diploids and tetraploids, are widely used in agricultural grassland systems, and yet limited knowledge exists on their competitive interactions after sowing. Two diploid cultivars (AberMagic, Twystar) and a tetraploid (Greengold), sown in different binary mixture ratios, were monitored over a 2-year period under frequent cutting to simulate cattle grazing and conservation managements. Composition was determined from fluctuations in phosphoglucoisomerase allozyme frequencies relative to the frequencies of the component cultivars.

An interaction occurred between cultivar sown ratio and seasonal period whereby greater changes in proportions occurred early in the first year. Cultivar proportions were significantly influenced by sown ratio, seasonal period and management. The diploid mixtures remained similar to their sown ratios, whereas the diploid–tetraploid mixtures, sown at 15% and 30%, increased to 33–61% under simulated grazing and 40–59% under conservation use. No changes were observed in the 50 : 50 diploid–tetraploid mixtures. A competitive equilibrium was attained after 1 year and compositions remained stable throughout the second year. The differences in large canopy structure between ploidies are a likely factor affecting competitive ability, and mixture construction should account for these hierarchies to achieve the desired sward composition.

Brevicoryne brassicae (Linnaeus), Lipaphis pseudobrassicae (Davis), Acyrthosiphon kondoi (Shinji), Aphis craccivora (Koch) and Rhopalosiphum padi (Linnaeus) are among the most important aphid pests in Australian broadacre systems. In this study a leaf-dip method was used to assay pirimicarb, dimethoate, α-cypermethrin and imidacloprid against field populations collected from Victoria, New South Wales, South Australia, Western Australia and Queensland. This research established toxicity baseline data that will be important for future monitoring of insecticide responses in broadacre crops. It also provided an opportunity to identify any chemical tolerance that may be evolving in these pests. Acyrthosiphon craccivora populations showed differences in their responses to dimethoate, pirimicarb and imidacloprid (but not to α-cypermethrin), indicating possible shifts in field sensitivity to these three chemicals. Rhopalosiphum padi had the lowest sensitivity to all insecticides tested, with two populations (collected from South Australia and Queensland) showing less than 100% mortality when tested at the field rate of α-cypermethrin. There were few differences in insecticide responses between populations of the other three species. Continued screening of A. craccivora and R. padi populations is needed to fully assess the current status of tolerance among field populations and to strengthen resistance management tactics.