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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]

Durante o período experimental de novembro de 1995 a abril de 1996 variáveis como disponibilidade de MS da planta toda, do resíduo pós-pastejo e das perdas de pastejo de uma pastagem de capim Tobiatã foram avaliadas. O ciclo de pastejo foi de 34 dias (33 de descanso e 1 de ocupação) para o lote principal de vacas de leite. Os dados obtidos foram divididos em períodos de pastejo e esses comparados entre si pelos testes de variância do recurso Proc-GLM do pacote estatístico SAS. Observou-se uma queda crescente na eficiência de colheita da pastagem a medida que o ciclo avançou. Em contrapartida, a quantidade de resíduo pós-pastejo aumentou. Eficiências de pastejo de 68,57% e 18,82% foram observadas quando a quantidade de resíduo foi 1491,50 e 7917,90 kg MS/ha durante os meses de novembro e abril, respectivamente. A composição botânica mostrou-se menos favorável com o avançar da estação de pastejo. A relação haste/folha aumentou de 0,33 para 1,92 do período de novembro/dezembro para abril/maio, respectivamente. Concluiu-se que a pressão de pastejo para o capim Tobiatã deve ser maior do que as utilizadas nesse experimento (8,84%PV) para que a eficiência de colheita aumente. A quantidade de resíduo pós-pastejo parece uma melhor como referência de manejo, como ferramenta para minimizar as perdas de pastejo.

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 effects of water stress on fodder beet (Beta vulgaris L.) production in the field are confounded by the influences of variable inter- and intra-season rainfall. In this study, a rain shelter experiment investigated the effect of water and nitrogen (N) stress on dry matter (DM) production, DM allocation and N partitioning in fodder beet ('Rivage'). Two water-management treatments, irrigated (replacement of the profile water lost weekly) and unirrigated (limited water applied only during fertigation), and three fertiliser N treatments (0, 50 and 300 kg N ha−1 (hereafter, 0N, 50N, 300N)) were evaluated during the 2016–2017 season. Under irrigation, the yield was greater (P =.02) for the 50N than 0N treatments (29.4 and 24.9 t DM ha−1, respectively). Yield did not differ (P =.42) between irrigated 50N and 300N (30.6 t DM ha−1) treatments, indicating surplus N application to the latter. Water and N stress restricted leaf growth, lowered N uptake and reduced yield by 48%–51%. Surplus N in irrigated 300N treatments resulted in increased N uptake and leaf proportion but reduced the storage root proportion. These results demonstrate the plasticity of fodder beet biomass and N allocation in adapting to the availability of water and N. [ABSTRACT FROM AUTHOR]

Two fodder beet (Beta vulgaris L.) cultivars ('Rivage' and SF Brigadier™) were evaluated in a field experiment to quantify the effect of cultivar and sowing date on growth physiology. The crops were sown on 19 September, 17 October, 17 November and 15 December in 2014. Crops were sequentially harvested and separated into storage root, leaf blade and petiole for analysis. Fodder beet growth was sigmoidal; the growth of leaf blades and petioles dominated the lag phase while storage root growth dominated the exponential phase. The appearance of the 25th leaf marked the beginning of the exponential phase. The maximum growth rate was not affected by the cultivar or sowing date. Total dry matter (DM) yield was the same for September- and October-sown crops (2444 ± 164 g DM m−2); showing little advantage of early sowing because cold temperatures slowed canopy development. The November- and December-sown crops produced 18% and 30% lower yield than the October-sown crops. 'Rivage' partitioned 5% greater DM to the storage root, an indication of greater sink strength, than SF Brigadier. Information on the pattern of growth can aid management decisions for optimising yield, and is valuable for the improvement of fodder beet models. [ABSTRACT FROM AUTHOR]