Faba bean (Vicia faba L.) is an important cool-season legume crop that ranks fourth after chickpea (Cicer arietinum L.), field pea (Pisum sativum L.) and lentil (Lens culinaris L.) in terms of total production. The global production of faba bean was 4.8 Mt in 2017, with China, Ethiopia and Australia being the largest producers (1.8, 0.93 and 0.37 Mt, respectively). However, its area of production is not increasing relative to other crops, mainly because of high yield instability. This can be attributed to several factors related to plant traits (e.g. phenology, morpho-physiology) and biotic and abiotic stresses. Faba bean has a very poor flower : pod ratio, with a maximum 20% of flowers resulting in pods. Environmental stresses such as frost, heat and drought cause significant damage to flowers and young pods; therefore, matching phenology of crops to the environment is important for avoiding or minimising detrimental effects of unfavourable environmental conditions. In order to improve adaptation and yield, we need to understand the main factors affecting plant growth, including biotic stresses, identify the main yield components, and find traits associated with tolerance to frost, heat and drought.

Zinc (Zn) deficiency in rotations of rice (Oryza sativa L.) and wheat (Triticum aestivum L.) impedes the productivity of both component crops. Fertilisation with Zn and switching to conservation tillage systems may help to improve soil health and the productivity of both rice and wheat. However, it is not clear whether, in conservation tillage systems, Zn application to either crop will fulfil the requirement of the following crop through a residual effect. This study was designed to evaluate the influence of Zn applied to wheat on the performance of rice under conventional (puddled transplanted rice, PuTR) and conservation (direct-seeded aerobic rice, DSAR) tillage. As a part of a long-term experiment, Zn was applied as foliage spray (FA, 0.025 M), by seed priming (SP, 0.5 M) and by soil application (SA, 10 kg ha^–1) in plough-till wheat (PTW) and no-till wheat (NTW). Controls without Zn application were included (PTW-C, NTW-C). After wheat harvest, rice was planted as PuTR and DSAR in each of the eight Zn application × wheat tillage treatment combinations. Compared with PuTR, DSAR significantly improved soil fertility (nitrogen, phosphorus, Zn), soil organic matter (1.5–4.5%), soil organic carbon (3%), soil microbial biomass carbon (2.5%) and grain yield (5.6%). Overall, DSAR preceded by NTW had higher soil organic carbon (4.3%), soil microbial biomass nitrogen (1.6%) and soil microbial biomass carbon (3.7%) than PuTR sown after either PTW or NTW. Residual Zn enhanced grain Zn concentration by 15% in rice planted after PTW-SA and 12% after NTW-SA. Overall order of improvement in rice-grain Zn concentration was PTW-SA = NTW-SA > NTW-C = NTW-SP. Likewise, higher grain yield with residual Zn availability was in the order DSAR-NTW-SA > PuTR-PTW-SA during 2018. Highest economic return with high benefit : cost ratio was recorded for DSAR-NTW-SA. Zinc application to the wheat crop effectively improved crop performance and grain quality of the following rice crop in both conventional and conservation tillage systems. However, the conservation system DSAR-NTW-SA may be chosen for improved soil health, and for increased harvest grain yield with better grain quality.

The rice (Oryza sativa L.) landrace Horkuch from Bangladesh maintains efficient photosynthesis and detoxification under salt stress and was therefore considered to be a useful donor for tolerance traits. Reciprocally crossed bi-parental mapping populations were generated from salt-tolerant Horkuch and high-yielding salt-sensitive variety IR29, in order to identify superior salt-tolerant high-yielding lines as donors. The present study reports on the phenotypic screening data of ∼300 F₃ segregating populations from the reciprocal cross and their parental lines in seedlings and screening of a subset at maturity stage under gradual salt stress of 12 dS m^–1 for seedlings and 8 dS m^–1 for mature plants. Correlation, broad-sense heritability and principal component analyses for salt tolerance as well as yield-related traits were conducted in the populations at the two developmental stages. Level of salt injury was found to be correlated with traits such as filled grain weight at maturity stage and biomass-related traits at the seedling stage. This association between yield-related and survival traits helped to identify tolerant and sensitive plants, which were predicative of agronomic performance under salt stress. Moreover, use of the reciprocal-cross population showed how cytoplasmic inheritance of specific traits such as K⁺ concentrations can affect characteristics of donor plants. Measurement of a large number of traits and analysis of their co-inherited interrelation can therefore help identify the best performing plants under salt stress for effective breeding strategies. The data are being utilised in mapping of quantitative trait loci, and selected progenies are being used as breeding lines for producing durable salt-tolerant, high-yielding rice varieties.

The quality and yield of wheat (Triticum aestivum L.) are dramatically affected by drought. We used morphological and physiological characteristics and degree of DNA methylation to compare the responses of two wheat cultivars under osmotic stress, and found that the two cultivars behaved differently. Root development, leaf growth, and the accumulation of proline and soluble carbohydrate in wheat cv. AK58 all showed drought tolerance. Drought tolerance of wheat cv. XM13 was mainly improved by accumulation of proline and soluble carbohydrate. The degree of DNA methylation in wheat showed tissue specificity and increased significantly in leaf tissue with increasing osmotic stress, but decreased significantly in root tissue under mild osmotic stress. In addition, changes of DNA methylation differed between two wheat cultivars under osmotic stress, and this change was especially significant in AK58. Therefore, wheat AK58 may have stronger self-adjustment ability under osmotic stress compared with XM13, and might respond more rapidly to osmotic stress through the change of DNA methylation. This finding could be significant for revealing drought-tolerance mechanisms of plants.

Early leaf senescence in wheat (Triticum aestivum L.) is one of the limiting factors for developing high yield potential. In this study, a stably inherited, early leaf-senescence mutant LF2099 was initially identified in an M₂ population of the common wheat accession H261 after ethyl methanesulfonate (EMS) mutagenesis. Early leaf senescence was observed in the LF2099 mutant during the three-leaf-stage, and then the etiolated area of the wheat leaf increased gradually from the bottom to the top throughout development. Compared with H261, the chlorophyll (Chl a, Chl b) and carotenoid contents and photosynthetic capacity of the mutant were significantly decreased. All of its yield-related traits except for spike length were also significantly reduced. Dissolved cytoplasm, abnormal chloroplast structure, dissolved chloroplast membrane, abnormal thylakoid development, and more plastoglobules were observed in the senescent leaf region of the mutant by transmission electronic microscope. Genetic analysis indicated that the early leaf-senescence phenotype is controlled by an incomplete-dominance nuclear gene, here designated Els2. Using single nucleotide polymorphisms and bulked segregant analysis, the els2 gene was anchored in a region on chromosome 2BL between simple sequence repeat (SSR) markers gpw4043 and wmc149. Six new polymorphic SSR markers were developed from the Chinese Spring 2BL shotgun survey sequence contigs. By means of comparative genomics analyses, the collinearity genomic regions of the els2 locus on wheat 2BL were identified in Brachypodium distachyon chromosome 5, rice (Oryza sativa) chromosome 4 and sorghum (Sorghum bicolor) chromosome 6. Five intron polymorphism (IP) markers were further developed from this collinearity genomic region. Ultimately, Els2 was mapped in a genetic interval of 0.95 cM flanked by IP markers 2BIP09 and 2BIP14. The co-segregating IP markers 2BIP12 and 2BIP17 provide a starting point for the fine mapping and map-based cloning of Els2.

Grain yield is frequently constrained by soil acidity in southern Australia yet limestone crushing plants are few and distant, making the use of limestone costly. The efficient technology of agricultural liming is therefore critical to the continuation of the practice following its adoption during the 1980s. We hypothesise that finer particles are the most effective materials for ameliorating soil acidity even over the longer term, when the residual value of coarser particles might be expected to be greater. Finer particle sizes of limestone, particularly <0.075 mm, initially gave the largest increases in soil pH per tonne of limestone applied. Despite the rapid and large increase in soil pH with finer particles, there was no less residual value in surface soil pH after 7 years or in grain yield in the 7th and 8th growing seasons compared with coarser particles. Most particle size fractions of limestone converged to a similar soil pH_ca at 0–10 cm depth after about 6 years but the coarsest particle size fraction (2–5 mm) lagged the other five. Finer particles also resulted in better movement of alkali and Ca into the subsurface soil layers below the depth of incorporation (0–10 cm). The measurement of unreacted limestone in the soil showed that the dissolution of limestone took up to 3 years (1807 mm of rainfall) for the 2.5 t/ha rate and up to 6 years (3592 mm) for the 5 t/ha rate. The rapid increase in soil pH in Year 1, the slow ongoing reaction of limestone over 3–6 years as measured by unreacted limestone, the slow but measurable improvement in subsurface acidity, and the sustained residual value to grain yield over in excess of eight seasons, indicate that the use of finer liming materials should remain a viable practice for growers.

Grown in water-limited environments, sorghum (Sorghum bicolor (L.) Moench) is often exposed to water deficits of varying extent and timing. One of the impacts of water stress on sorghum production is lodging; however, there has been no published study quantifying the temporal and spatial frequency and severity of lodging in grain sorghum in Australia. In this study, we investigated the frequency and severity of lodging, using a dataset of 83 advanced yield-testing trials of the sorghum pre-breeding program grown in the seven major sorghum-production environments in Australia over 14 summer growing seasons. Lodging occurred in most production regions but with varying frequency and severity. Lodging was significantly greater in regions that were more prone to water stress (e.g. Central Highlands in Queensland) and significantly lower in regions that were less likely to suffer from water stress (e.g. Liverpool Plains in northern New South Wale) compared with the overall average across regions. The severity of lodging also varied across regions, with the most severe lodging (>20%) occurring in Central Highlands and Western Downs in Queensland. In addition, seasonal patterns of lodging frequency and severity were also observed. Over the 14 growing seasons, the frequency of lodging varied from 0% to 100%, with the most severe lodging (>20%) observed in 2005, 2016 and 2017. The Southern Oscillation Index explained 29% of the seasonal variation in lodging frequency. The findings of this study clearly support a link between lodging incidence and water stress across regions and seasons. Our data also showed that although there was a substantial turnover of commercial hybrids during the period of this study, the level of resistance to lodging appeared not to have improved. It is possible that this is due to plant breeders trading off improvements in lodging resistance to increase grain yield.

Phalaris aquatica is known to cause toxicity in livestock in the form of acute or chronic staggers or sudden death neurological (SDN) syndrome. Breeding of cultivars that produce lower concentrations of suspected alkaloid toxins has been conducted, but these cultivars continue to cause staggers and SDN toxicity. Field samples of grazed phalaris pasture were collected during one growth season (February–June 2016), and from pastures where cases of staggers and/or SDN had occurred in previous years, and immediately after two cases of toxicity. Pasture collected from a paddock where a case of SDN occurred 4 days prior had elevated levels of 5-methoxy-N,N-dimethyltryptamine (5-MeO DMT) and slightly elevated levels of dimethyltryptamine (DMT) compared with other collections from the region. Pasture collected from a paddock at the time of a case of phalaris staggers did not have elevated levels of the quantified alkaloids. Across the measurement period, potentially toxic alkaloids gramine, hordenine, DMT and 5-MeO DMT were observed to decrease in concentration, whereas β-carboline (norharmane) was not detected in any sample. Excessive drying out of dormant plants was hypothesised to be a risk factor for phalaris toxicity. Continued management of potentially toxic phalaris pasture could include measures to manipulate the physiological processes that result in increased toxic alkaloids, including methods to reduce drying out of dormant phalaris plants, and managing stocking rates and grazing species to mitigate potential toxicity.

In the American tropics, livestock production is highly restricted by forage availability. In addition, the breeding and development of new forage varieties with outstanding yield and high nutritional quality is often limited by a lack of resources and poor technology. Non-destructive, high-throughput phenotyping offers a rapid and economical means of evaluating large numbers of genotypes. In this study, visual assessments, digital colour images, and spectral reflectance data were collected from 200 Urochloa hybrids in a field setting. Partial least-squares regression (PLSR) was applied to relate visual assessments, digital image analysis and spectral data to shoot dry weight, crude protein and chlorophyll concentrations. Visual evaluations of biomass and greenness were collected in 68 min, digital colour imaging data in 40 min, and hyperspectral canopy data in 80 min. Root-mean-squared errors of prediction for PLSR estimations of shoot dry weight, crude protein and chlorophyll were lowest for digital image analysis followed by hyperspectral analysis and visual assessments. This study showed that digital colour image and spectral analysis techniques have the potential to improve precision and reduce time for tropical forage grass phenotyping.