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In New Zealand, facial eczema (FE) is a serious health and welfare issue for grazing ruminants caused by ingesting toxic spores of the fungus Pseudopithomyces chartarum.A literature review of research about the effect of pasture plant species, farm management practices and associated environmental factors on FE in New Zealand, was undertaken. An important outcome of this research has been the development of spore count techniques used on-farm to monitor P. chartarum during the summer/autumn risk period. Other research outcomes include: Reduce pasture litter (decaying herbage) by hard spring grazing, with minimal topping, and use pasture species that reduce litter.Avoid hard grazing during the riskiest autumn period.Minimise grazing of perennial ryegrass dominant pastures by increasing legume content or use the less risky species such as tall fescue.Utilise specialist (non-ryegrass) legume and herb-based pastures that provide less litter, are grazed to higher residuals, and provide high-quality feed.Future FE research should focus on the incorporation of ‘high-quality’ FE-safe species, such as tall fescue, legumes and herbs, into existing farming systems. They can enhance feed supply during the summer/autumn FE risk period but require appropriate management guidelines to maximise production and persistence.Reduce pasture litter (decaying herbage) by hard spring grazing, with minimal topping, and use pasture species that reduce litter.Avoid hard grazing during the riskiest autumn period.Minimise grazing of perennial ryegrass dominant pastures by increasing legume content or use the less risky species such as tall fescue.Utilise specialist (non-ryegrass) legume and herb-based pastures that provide less litter, are grazed to higher residuals, and provide high-quality feed. [ABSTRACT FROM AUTHOR]

Legumes have underpinned transformational change on New Zealand sheep and beef farms over the last 30 years. This was through an emphasis on ewe nutrition based on lucerne or red clover dominant pastures, and increased use of subterranean and white clovers on uncultivatable hill country. Pre- and post-weaning lamb growth rates have increased, and enabled earlier slaughter of heavier lambs. The farm systems results include greater numbers of hoggets mated, higher lambing percentages and greater ewe efficiency (kg lamb weaned/kg ewe mated). Extension packages to support legume use have compared growth rates of resident and legume-based pastures, economic analyses of successful farms and management packages for the most appropriate legume in different environments. Over the same period, the dairy industry rapidly expanded in cow numbers and area onto flat irrigated land on the Canterbury Plains. The nitrogen deficiency of perennial ryegrass was overcome by a linear increase in nitrogen fertiliser use. Environmental concerns from this intensification has led to a legislated nitrogen cap of 190 kg/ha.year. This, coupled with a recent trebling in urea price, has returned attention to increasing the white clover content of these pastures. Nitrogen applications can be minimised by using diverse pastures sown with a legume, herb and <8 kg/ha of perennial ryegrass. Work on other legumes, including annuals and those with condensed tannins, has to date failed to increase their use in most pastoral settings, with the exception of the perennial lupin which is adapted to high-aluminium soils in the South Island High Country. Legumes have underpinned the New Zealand pastoral-based economy for over 100 years. White clover remains the most widely sown, but specialist red clover based pastures are providing high quality feed for fattening livestock in wetter regions of the country. In the drier east coast, lucerne management has been refined based on crop physiology principles. This has allowed earlier lambing, leading to transformational change on-farm. Subterranean clover remains the dominant annual legume used. Successful integration of legumes on-farm has required understanding of the genotype by environment by management interactions. [ABSTRACT FROM AUTHOR]

Atmospheric carbon dioxide concentrations ([CO2]) are increasing, but little is known about how this will affect macronutrient (nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)) accumulation and partitioning in the aboveground biomass (AGB) for different hard spring wheat genotypes. We examined the responses of six spring wheat genotypes ('Discovery', 'Duchess', 'Reliance', PFR-3026, PFR-3019, PFR-2021) to two CO2 levels (ambient [aCO2] and elevated [eCO2]) and six nitrogen rates (N; 1–10 mM), at the stem elongation growth stage of wheat grown in controlled environment chambers. The AGB yield increased by 35.2% with increasing [CO2] when N rate was >2 mM. Increasing N supply also increased AGB by up to 3.2-fold over the entire N range applied. The AGB responses to N differed among the genotypes, being lowest for PFR-3019 (7.71 ± 0.11 g/pot) and highest for PFR-2021, PFR-3026 and Duchess at 8.84 ± 0.11 g/pot at both CO2 levels. Macronutrient concentrations decreased with eCO2 by 28.0% for Ca to 17.4% for P and K. Nevertheless, absolute nutrient uptake was higher for eCO2 treatments, because the AGB increase (20.0–52.0%) was proportionally higher than the 4.0–28.0% increase in nutrient uptake. The AGB non-response to [CO2] at N rates <2mM indicates that this nutrient deficiency was more limiting than the effects of CO2 level. Therefore, the impact of eCO2 in the future will depend on N fertilizer management. These results suggest that critical nutrient concentrations used to diagnose the nutrient status of wheat crops will need to be reassessed for eCO2 conditions. [ABSTRACT FROM AUTHOR]

Radiation interception, radiation use efficiency (RUE) and harvest index (HI) are the key determinants of grain yield in cereal species. However, little is known about how these traits affect grain yield among spring wheat genotypes grown under low and optimum nitrogen (N) fertiliser supply. We used two experiments, in a field (Experiment 1; 2017–2018) and glasshouse (Experiment 2; 2018–2019) to investigate the effects of these traits on grain yield. Grain yield increased by 35% with increasing N fertiliser supply to 8.80 t/ha in Experiment 1 and 151% to 8.33 t/ha in Experiment 2. Grain yield was lowest for 'Reliance' and highest for 'Discovery' in both experiments. Differences in grain yield were not associated with HI. As the RUE did not differ among genotypes, the yield differences were attributed to the different amounts of radiation intercepted; a result of the faster leaf area expansion rate (LAER) and subsequent higher maximum green leaf area index (GLAI), and a longer leaf area duration (LAD). The differences in LAER and maximum GLAI among the genotypes were associated with a differences in specific leaf area (cm2/g). Our results suggest that improved grain yields in spring wheat can be achieved by focusing breeding efforts on canopy characteristics to increase radiation interception. [ABSTRACT FROM AUTHOR]

The New Zealand economy is export-driven and heavily reliant on the productivity of the pastoral sector. The transformation of native forest and tussock grassland ecologies to temperate grasslands occurred rapidly with the arrival of Europeans. However, this transplanted ecology required the development and use of plant, microbial, animal and management technologies for successful grassland farming. These have enabled New Zealand pastoral agriculture to compete effectively in international markets, without subsidies. The extensive list of plant-based and associated microbial-based adaptations, and the management strategies that have enabled the development of highly productive grasslands are described and reviewed. Credible science is required to inform the debate on the environmental impacts of pasture production to avoid misinformation proliferating. This needs transparent and objective integrity from the science community using funding that seeks no defined or preconceived outcomes. Critically, much of the success of New Zealand pastoral farming has been due to the willingness and ability of farmers to use, adapt, adopt and integrate new ideas and technologies into their farming systems. Historic, current and future challenges, and threats that impact on the productivity and sustainability of pastoral agriculture are described and the means to achieve further technology development to manage these is discussed. [ABSTRACT FROM AUTHOR]

Analyses of New Zealand farm systems require estimates of herbage yield and quality. These are available for perennial ryegrass and white clover pastures but not for other common pasture species. We used five lucerne datasets to derive functional relationships between growth rate and temperature. This required three functions to account for partitioning in lucerne between spring and autumn and differences between seedling and regrowth crops. The maximum mean daily growth rate of 206 ± 5.95 kg DM/ha/d occurred with full canopy cover at mean air temperatures between 15°C and 22°C. This represents the upper end of the temperature range available. The relationship was summarised into a matrix that could be incorporated into existing forage forecasters for farm system analyses. Alternatively, a simplified model assessed growth rate in relation to thermal time. This showed after 140°Cd accumulated from 1 July, lucerne initiated spring growth at 11.9 kg DM/ha/°Cd until mid-January and then decreased to 6.7 kg DM/ha/°Cd from mid-January to 30 June for fully irrigated crops. An exponential heightchron relationship was also calculated to estimate crop height based on the thermal time required per mm as photoperiod changed. This relationship allows lucerne quality to be predicted from the leaf:stem ratio. [ABSTRACT FROM AUTHOR]

The annual regeneration from seeds of subterranean clover plants after initial sowing depends on the hardseededness (HSmax, %), its breakdown rate (HSbreak, %/ °C) and the germinability of the seeds over time. Hardseededness is a physical mechanism of dormancy that prevents germination of seeds and is ecologically important for the persistence of subterranean clover in a range of environments. The effects of genotype (G) and sowing time (environment, E) on hardseedednes and germination were investigated for 'Antas', 'Denmark', 'Leura', 'Monti', 'Narrikup' and 'Woogenellup' harvested from six different sowing dates (June 2015–March 2016) in a field experiment in Canterbury, New Zealand. 'Antas' had a lower HSmax (53%) than 'Monti' (86%). HSbreak was affected by the G x E interaction with a doubling of HSbreak from 0.011%/°C for the June sowing date to ∼0.02%/°Cd for the February sowing date for 'Denmark', 'Leura', 'Monti' and 'Narrikup'. There was less sensitivity of 'Antas' and 'Wogenellup' to sowing time. There was an increase in the percentage of abnormal seedlings as the sowing date advanced from winter to late-summer. The developed parameters enabled estimation of seedling emergence and indicate cultivars which have a competitive advantage of an early seedling regeneration in temperate regions. [ABSTRACT FROM AUTHOR]