Context. Investigating agronomic responses of dryland maize (Zea mays L.) systems under global change could provide important insights in designing climate-resilient cropping systems.

Aims and methods. In this study, we integrated Agricultural Production Systems sIMulator (APSIM) with Representative Concentration Pathways 8.5 and 20 Global Climate Models to systematically: (1) calibrate and validate APSIM using large-field study conducted in East-Central Texas; (2) evaluate the impacts of climate change on maize productivity and risks; and (3) investigate the variations in growth stage lengths.

Key results. Results indicated that APSIM simulated grain yield, biomass production, precipitation productivity (PP; kg ha^-1 mm^-1) and developmental stage transition agreed well with observation (NRMSE < 14.9%). Changes in temperature and precipitation shortened growing seasons and affected available water, resulting in widely varied yield and PP. Mean grain yield changed from -34.8 to +19.7%, mean PP were improved 9.2-36.5%. The grain production could be maintained at least the standard of 75% of historical in most cases, but with greater risks for achieving higher threshold (50% of baseline). Finally, simulations indicated shortened days (4-13 days) for reaching key developmental stages for maize.

Conclusions and implications. The results advocate adoptions of management practice that incorporating early sowing, irrigations at sowing/VT stages, and selections of late-maturing cultivars for better sustainability and higher productivity.

Context. The fungal endophyte Serendipita indica enhances plant growth and plant resistance to biotic and abiotic stresses. Inoculum concentration greatly impacts the endophyte-plant interaction from mutualism to antagonism.

Aims and methods. We used both microscopy and qPCR to examine the effect of inoculum concentrations on the extent (%) and density of Brassica napus L. root colonisation by S. indica. B. napus seeds were inoculated with the fungus at five different inoculum concentrations (1-10% w/w basis).

Key results. Standard curves were constructed using the mean threshold cycle (Ct) and serially diluted gDNA ranging between 4.14 × 10² and 2.65 × 10⁵ colony forming units (CFU). The result indicated a linear relationship between Ct and the log of input DNA. Variation in inoculum concentration significantly affected the root colonisation density by the fungus shown by qPCR. However, the percent root colonisation (PRC) measure was not affected and remained the same across all the treatments.

Conclusions. Our findings show that the qPCR assay developed will determine the colonisation density whereas PRC gives a measure of the incidence of infected roots. Also, we suggest that the optimum quantity of inoculum is a key factor for a successful interaction that impacts the plant-S. indica interaction.

Implications. To our knowledge, this is the first study that quantitative qPCR has been used to investigate the correlation between inoculum quantities and the corresponding density of root colonisation in S. indica.

Fungicide use has become a fundamental part of many crop protection systems around the world, including to control blackleg disease on canola (Brassica napus L.). In Australia, most canola growers routinely apply at least one fungicide, and potentially multiple fungicides with different modes of action, in a single growing season. There is evidence for the emergence of fungicide resistance in Leptosphaeria maculans, the causal agent of blackleg disease, to the demethylation inhibitor (DMI) class of fungicides in Australia. However, it is not known whether resistance exists towards other chemical classes such as the succinate dehydrogenase inhibitors (SDHI). In this work, 397 samples were screened for resistance towards seven fungicide treatments in stubble-borne L. maculans populations collected from eight canola-growing agro-ecological regions of Australia from 2018 to 2020, a time frame that bridges the introduction of new chemicals for blackleg control. We confirmed that DMI resistance in L. maculans is pervasive across all of the sampled canola-growing regions, with 15% of fungal populations displaying high levels (resistance scores >0.5) of resistance towards the DMI fungicides. Although resistance to newly introduced SDHI fungicides was low, we found evidence of positive cross-resistance between established DMI-only fungicides and a newly introduced combined DMI and quinone outside inhibitor fungicide, suggesting that the efficacy of the latter may be limited by widespread DMI resistance. Proactive surveillance, as performed here, may provide a means to avoid the rapid loss of fungicide efficacy in the field.

Fennel (Foeniculum vulgare Mill.) is an old medicinal plant and has been commonly used as a traditional food and medicine. This study aimed to evaluate genetic variation for agro-morphological traits and essential oil content and components in a worldwide collection of bitter fennel (F. vulgare var. vulgare). We examined production stability of different accessions, and identified associations between traits in order to find the best criteria for use in future breeding programs. The study evaluated 33 bitter fennel accessions from 11 countries in the field for morphological characters across 4 years (2015-18), and for important phytochemical characters in 2 years (2015 and 2016). Comparisons across years revealed varied responses from fennel genotypes. Highest mean production was observed in the third year, and highest essential oil content in the second year. Based on gas chromatography-mass spectrometry analysis, trans-anethole (59.86-78.82% of total oil content), estragole (3.61-24.39%), fenchone (9.58-18.26%) and limonene (0.52-3.66%) were detected as major essential oil components in the studied germplasm. Based on principal component and cluster analysis, genotypes were grouped into different clusters. Classification of genotypes was mainly in agreement with available information regarding their origins. The results support available information on the history of human establishments and the introduction of fennel from Mediterranean gene pools to other regions in ancient times. The negative correlation between some essential oil components indicates that some components are isomers and this could limit the simultaneous selection of components. Superior genotypes were identified in the studied germplasm, which can be used for future breeding programs with specific purposes.

Trifolium subterraneum L. subsp. yanninicum is a pasture legume that is widely grown in medium and high rainfall areas of southern Australia and shows waterlogging tolerance. This study investigated diversity within subsp. yanninicum corresponding to eco-geographic variables, which may help to identify adapted parents with new traits for genetic improvement. Diversity for 10 morphological traits, flowering time and leaf isoflavone content was investigated using 108 ecotypes derived from wild Mediterranean populations and 10 cultivars, grown as spaced plants. Among the ecotypes, the range of flowering time was 94-149 days after sowing, and contents of formononetin, genistein and biochanin A were 0.05-1.38%, 0.73-2.33% and 0.15-2.10% of dry matter, respectively. Leaf markings also varied considerably. Leaf size and petiole length were correlated at each growth stage. Later flowering genotypes had larger leaves, longer petioles, longer internodes and thicker stems at flowering, but smaller leaves and shorter petioles at both 63 and 88 days after sowing. Contents of genistein and biochanin A were unrelated, but both were negatively associated with formononetin. Flowering time had a weak positive influence on genistein and biochanin A, but a weak negative influence on formononetin. All traits among the ecotypes (except stem diameter and leaf mark crescent size) were significantly correlated with at least one of 22 eco-geographic variables from their collection sites. Precipitation and altitude were more influential than temperature. The study found sufficient diversity to broaden the narrow genetic base of current subsp. yanninicum cultivars; however, other agronomically important traits also need to be considered. Further diversity may result from targeted collection, particularly in areas not represented in annual legume genebanks.

Context. The effect of long-term gypsum on nitrogen (N) responsiveness in black oat (Avena strigosa Schreb.) forage lacks information.

Aims and methods. This study evaluated interactions between different rates of N (0, 50 and 100 kg N ha^-1) and gypsum (0, 3, 6, 9 and 12 Mg ha^-1) on the yield, nutrition and bromatology of forage black oats in a long-term experiment using a no-till system (NTS) in a Ferralsol in southern Brazil.

Key results. There was an interaction between residual gypsum and N rate on biomass forage yield in 2015, but not for the 2016 growing season. In 2015, the rate of 100 kg N ha^-1 increased yield by 10% in the absence of gypsum and by 30% at low-medium rates of residual-gypsum (3 and 6 Mg ha^-1), but there was no response to high N rate under high gypsum rates (9 and 12 Mg ha^-1). In 2016, a poor-growing season, a gypsum rate of 6 Mg ha^-1 and N rate of 100 kg ha^-1 independently improved forage yield by 5%. Gypsum application produced higher forage contents of N, P, K, Ca and S, and decreased Mg content. N-fertilisation increased the N, K, Ca, and Mg contents, but decreased P content and S concentration. Gypsum had no effect on forage bromatological quality, and even with equivalent forage yield between 50 and 100 kg N ha^-1, only the high N rate improved some of the forage quality attributes in both years.

Conclusions and implications. Neither gypsum nor topdressing of N altered N use by black oat forage.

Common vetch (Vicia sativa subsp. sativa) is one of the most economically important forage legumes, with high nutritional value and multiple uses. Although microsatellite markers have been developed and applied on a large scale for evaluation of common vetch germplasm, intron-length polymorphic (ILP) markers have not been systematically investigated and exploited. In this study, introns within the common vetch genome were located by aligning the RNA-Seq sequences of common vetch with barrel medic (Medicago truncatula), soybean (Glycine max) and Arabidopsis thaliana genome sequences, and then used for VsILP marker development. In total, 10 400 markers were generated from 44 582 common vetch unigenes. Of 300 randomly selected VsILP markers, 283 were successfully amplified in common vetch. Among these markers, 40 produced length variation in 30 accessions of common vetch, collectively yielding 166 alleles with an average of 4.0 alleles per locus. The polymorphic information content values extended from 0.06 to 0.81 with a mean of 0.49. Of the 283 VsILP markers, 84.8% exhibited transferability to other species, both leguminous (common vetch, lucerne (Medicago sativa), barrel medic, soybean, yellow sweet clover (Melilotus officinalis), Lotus corniculatus and Sophora alopecuroides) and non-leguminous (rice (Oryza sativa), Arabidopsis and tobacco (Nicotiana tabacum)). Here, we present the first large-scale development of ILP markers in common vetch and their utility in germplasm evaluation and transferability, which will be valuable for further comparative genomic studies, genetic relationship assessments, and marker-assisted breeding of leguminous and non-leguminous species.