In the Czech Republic, Barley yellow dwarf virus (BYDV) and Wheat dwarf virus (WDV) are the prevailing viral species that can cause significant yield losses in cereal stands. Another virus, which has been on the increase in the Czech Republic and whose impact is expected to increase, is Wheat streak mosaic virus (WSMV). In this study, a TaqMan Multiplex Real-Time (qPCR) assay for simultaneous detection of BYDV (species PAV, PAS and MAV), WDV and WSMV was developed. Furthermore, additional assays for the viruses’ quantification in wheat and barley were developed. The assay was optimised and used to identify possible synergistic or antagonistic relations between the viruses in wheat and barley which would be characterised by increases or decreases of the titre of the individual viruses. For this, a greenhouse experiment with artificial inoculations of mixed and single infections of BYDV-PAV, WDV and WSMV was carried out, and field samples from the wheat and barley stands with mixed and single infections of BYDV and WDV were collected. No trend of increasing or decreasing titre was recorded for any of the viruses apart from WSMV titre which was decreased approximately five times in mixed infections with BYDV or WDV compared with the single WSMV infection. Further analyses are needed to expand the idea of possible interactions between WSMV and WDV or BYDV.

The phytopathogenic fungus Sclerotinia sclerotiorum forms dormant structures (termed sclerotia) that germinate myceliogenically under certain environmental conditions. During myceliogenic germination, sclerotia produce hyphae, which can infect leaves or stems of host plants directly from the ground; this is termed basal infection. This study determined which abiotic conditions were most important for promoting myceliogenic germination of sclerotia in vitro. A high sclerotium hydration level and low incubation temperature (15°C) improved mycelial growth in the presence of a nutrient source. Sclerotia incubated without a nutrient source on moist sand, vigorously myceliogenically germinated most frequently (63%) when they had been previously imbibed and then conditioned at −20°C. By far the most consistent amount of vigorous myceliogenic germination (>75%) was produced when sclerotia were heat-dried before being submerged in water. The hyphae of these sclerotia were shown to infect and proliferate on leaves of intact Brassica napus plants. This research provides a better understanding of the abiotic conditions that are likely to increase the risk of basal infection by S. sclerotiorum.

The small-seeded legumes are important forage crops for grazing animals and contribute nitrogen to succeeding crops in crop rotation systems. However, the susceptibility of several of the forage legumes to the specialist pea aphid Acyrthosiphon pisum (Harris) has never been investigated. The present study on aphid probing behaviour using the Electrical Penetration Graph technique revealed that the forage legumes studied were (i) highly acceptable (common vetch Vicia sativa L.), (ii) acceptable (wooly vetch Vicia villosa Roth), (iii) moderately acceptable (fodder galega Galega orientalis Lam., crimson clover Trifolium incarnatum L., Persian clover Trifolium resupinatum L., white clover Trifolium repens L.), (iv) barely acceptable (common bird’s-foot-trefoil Lotus corniculatus L., yellow lucerne Medicago falcata L., alfalfa Medicago sativa L., sand lucerne Medicago × varia Martyn, common bird’s-foot Ornithopus sativus Brot., alsike clover Trifolium hybridum L., red clover Trifolium pratense L., common sainfoin Onobrychis viciifolia Scop.), and (v) unacceptable (white melilot Melilotus albus Medik.) to the pea aphid. On (i) plants, probing occupied 85% of experimental time, all aphids (100%) succeeded in feeding on phloem sap, phloem phase occupied 50% of probing time, sap ingestion periods were long (mean duration: 100.8 ± 28.2 min.) and engaged 97% of the phloem phase. On (ii) plants, probing occupied 73% of exp. time, feeding activity occurred in 66.7% of aphids, phloem phase occupied 30% of probing time, sap ingestion periods were long (mean duration: 115.5 ± 46.7 min) and engaged 80% of the phloem phase. On (iii) plants, probing ranged from 53% of exp. time on T. repens to 70% on T. incarnatum and T. resuspinatum, feeding occurred in 35.3% of aphids on T. resuspinatum up to 54.5% on T. incarnatum, phloem phase occupied 10% of exp. time on G. orientalis, T. incarnatum, and T. resuspinatum and 20% on T. repens, sap ingestion periods were from 9.8 ± 1.8 min. on G. orientalis to 51.9 ± 20.7 min. long on T. resuspinatum and engaged from 30% of phloem phase on G. orientalis to 80% on T. incarnatum. On (iv) plants, probing occupied 25% of exp. time on O. viciifolia up to 38% on O. sativus and T. hybridum, feeding occurred in 6.7% of aphids on T. hybridum to 28% on O. sativus, phloem phase occupied less than 1% of probing time on all plants except O. viciifolia (4%) and O. sativus (5%) and it consisted mainly of salivation. On M. albus (v), probing occupied 22% of experimental time, the probes were short (1.8 ± 0.3 min), and no aphid on M. albus showed feeding on phloem sap. M. albus can be recommended for intercropping, ‘push-pull’ strategies, or as a barrier crop against A. pisum in sustainable agricultural practices.

Agroforestry (the integration of trees into agricultural landscapes) has been promoted, in Australia and elsewhere, as a way to increase farm productivity by providing a wide range of benefits. Despite this, adoption of agroforestry in Australian agricultural systems remains low. To implement agroforestry, farmers must be convinced the benefits of including trees outweigh the costs. This review evaluates the available quantitative data on shelter benefits with emphasis on Australian conditions, identifies key research gaps and determines if there is sufficient knowledge to make accurate predictions about impacts on farm productivity.

Availability of quantitative data on windbreak shelter benefits was examined in five key areas; water use and evaporation, crop/pasture production, livestock mortality, livestock productivity and the capacity to model impacts of windbreaks on crop/livestock systems. Good quantitative data exists for many areas, particularly for changes in environmental conditions following tree establishment, however there were many gaps in key areas. Importantly, the ability to predict crop growth under spatially and temporally variable environmental conditions and the impact of windbreaks on livestock productivity is not yet able to be meaningfully quantified. Thus modelling the profitability of windbreaks is difficult and existing models require additional quantitative data to validate and improve them.

Three species of Desmanthus adapted to the heavy clay soils of northern Australia were studied to determine their nutritive value and effects on in vitro fermentation with rumen fluid, compared with Rhodes grass (Chloris gayana) hay. Leaves and stems of D. leptophyllus cv. JCU 1, D. virgatus cv. JCU 2 and D. bicornutus cv. JCU 4 were collected in summer, winter and spring of 2014 and analysed for chemical composition. Apparent digestibility as in vitro organic matter digestibility (IVD-OM) and fermentation parameters including methane (CH₄) production were measured during 72-h fermentations using rumen fluid from steer donors grazing tropical grasses and legumes. Desmanthus bicornutus was on average more digestible than both D. leptophyllus and D. virgatus at 24, 48 and 72 h of incubation. This species also demonstrated an anti-methanogenic potential, in particular when harvested in summer with a reduction in CH₄ production of 26% compared with Rhodes grass hay after 72 h of incubation. At this time point, D. leptophyllus produced higher volatile fatty acids (VFA per g of organic matter fermented) compared with the other forages. This legume also reduced the CH₄ production up to 36% compared with the Rhodes grass hay reference. However, D. leptophyllus showed lower IVD-OM. Overall, Desmanthus species produced lower in vitro CH₄ and lower volatile fatty acids concentration compared with the reference grass hay. These effects may be due to presence of secondary compounds such as hydrolysable tannins, condensed tannins and/or their combination in Desmanthus species. The IVD-OM was influenced by the season after 72 h of incubation; the digestibility was higher in plants collected in spring. This study suggests that contrasting fermentative profiles in Desmanthus cultivars may offer the opportunity to reduce the greenhouse gas contribution of the beef industry. The next step in demonstration of these promising in vitro results is demonstration of Desmanthus in vivo as proof of concept confirming the productivity and CH₄ reduction ability of these legumes in the pastoral systems of northern Australia.

In many south-eastern Australian dairying regions, supraoptimal ambient temperatures (T_a > 30°C) often challenge the perennial ryegrass (Lolium perenne L.)-dominated feed-base during the summer months. A glasshouse experiment was undertaken to identify alternative summer-active temperate (C₃) perennial forages more tolerant of supraoptimal temperature stress (day/night T_a of 38/25°C) than perennial ryegrass. Supraoptimal temperature stress was imposed both with and without irrigation. Chicory (Cichorium intybus L.) was the only species to survive 18 days of combined supraoptimal temperature stress and non-irrigation. Lucerne (Medicago sativa L.), plantain (Plantago lanceolata L.), and tall fescue (Festuca arundinacea Schreb.) survived 12 days of this treatment. Twelve days of exposure to these conditions caused death of perennial ryegrass, prairie grass (Bromus catharticus Vahl.), cocksfoot (Dactylis glomerata L.), birdsfoot trefoil (Lotus corniculatus L.), and red clover (Trifolium pratense L.). Irrigation (daily to through drainage) mitigated detrimental effects of imposed supraoptimal temperature stress on the growth and survival of all species. Chicory and to a lesser extent lucerne, plantain, and tall fescue may have a role to play in south-eastern Australian dairying regions, where supraoptimal temperature stress is a frequent and ongoing issue.

Climate change projections for Portugal showed warming and drying trends, representing a substantial threat for the sustainability of forage production in perennial grassland. The objective of the present study was to assess climate change impacts on seasonal dry matter yield (DMY) in three locations (North-west-, Central-inner and South-Portugal) with different climatic conditions, for two grassland production systems deviating in growing season length, either early cuts in spring (ES) or late cuts in summer (LS). Impacts were estimated using the STICS (Simulateur mulTIdisciplinaire pour les Cultures Standard) crop model, by comparing a historical baseline period (1985–2006) with simulated projections over future periods (2021–2080). For this purpose, the STICS crop model was driven by high-resolution climate data from a coupled Global Climate Model/Regional Climate Model chain. As a result, we obtained that, during the baseline period, DMY of LS was consistently much higher than that of ES in all three locations. For LS, significant reductions in mean DMY were forecasted during 2061–2080, ranging from mild (–13%) in the north to severe (–31%) in the south of Portugal. In contrast, seasonal DMY was largely maintained for ES among sites until 2080, benefiting from low water deficits, the expected atmospheric CO₂ rise and the forecasted temperature increase during cool season. Thus, the yield gap was projected to gradually decrease between the two regimes, in which mean DMY for ES was foreseen to exceed that of LS over 2061–2080 in the southern site. Moreover, ES was projected to have very low exposure to extreme heat and severe water stresses. Conversely, LS, subjected to high summer water deficit and irrigation needs, was projected to experience increased summertime water stress (9–11%) and drastically increased heat stress (33–57%) in 2061–2080, with more pronounced heat stress occurring in the south. Frequency of occurrence of extreme heat stress was projected to gradually increase in summer over successive study periods, with a concomitant increased intensity of DMY response to inter-annual variability of heat stress during 2061–2080. Heat stress tended to be more important than water stress under the prescribed irrigation strategy for LS, potentially being the main limiting factor for summertime DMY production under climate change scenario.

The invasive herbaceous species Parthenium hysterophorus L. (Asteraceae), commonly known as parthenium weed has rapidly become a significant weed in more than 30 countries. Parthenium weed litter taken from the introduced biotypes was relatively more phytotoxic than that taken from biotypes coming from the native range when tested on lettuce and this may indicate one reason for invasion success. However, no significant difference was observed in phytotoxicity to lettuce seedling growth when two Australian biotypes of parthenium weed were compared, one invasive and one non-invasive, indicating that invasiveness was not associated with litter phytotoxicity in all cases. Residue from the invasive parthenium weed biotype had a greater phytotoxic effect upon Australian native pasture grass species relative to the introduced pasture grass species with buffel grass (Cenchrus ciliaris L.) and bull Mitchell grass (Astreble sequarrosa C.E.Hubb) showing the greatest tolerance to parthenium weed phytochemicals. When compared with residue taken from plants that has a range of phytotoxic capacity, parthenium weed residue was considered to be only moderately phytotoxic suggesting that the phytotoxicity of its residue may not be the main reason for the plants invasive trait.

Low plant-available phosphorus (P) in degraded arid steppes greatly limits plant yields. However, whether exterior P addition will improve the soil P availability and thus increase plant yield in these degraded arid steppes is still not certain. In the current study, a severely degraded arid steppe in Inner Mongolia, China, with soil-available P <5 mg/kg, was fertilised annually with chemical or manure P for two years (2014, dry year; 2015, wet year). There were six fertilisation treatments: 0, 30 kg P/ha, 60 kg P/ha, 90 kg P/ha, 4000 kg sheep manure/ha (equalling 16.4 kg P/ha) and 8000 kg sheep manure/ha (32.8 kg P/ha). A pot experiment with Stipa krylovii (the dominant plant species in the tested steppe) and five P application rates (0, 30, 60, 90 and 120 kg P/ha) was also conducted, under well-watered and nitrogen-fertilised conditions, using surface soils from unfertilised plots in the field. Results indicated that the tested soils had strong P adsorption capacity and weaker desorption capacity, and that the labile P fractions were quickly transformed into less labile fractions, reducing P availabilities. Overall, chemical P fertiliser resulted in the accumulation of Ca₁₀-P and occluded P, whereas sheep manure resulted in the accumulation of moderately resistant organic P and highly resistant organic P. Phosphorus fertilisation was associated with an increase in plant P concentrations in both 2014 and 2015, and a low P rate (30 kg P/ha in the current study) was able to improve the aboveground biomass in both the field experiment in the wet year and the pot experiment under well-watered conditions. Thus, in degraded arid steppes, P fertilisation may be unnecessary in dry years. A low rate of P fertilisation is recommended in wet years to improve soil P status and steppe plant productivity.