The development of knowledge on bread wheat (Triticum aestivum L.) biofortification in zinc (Zn) and iron (Fe), related to its potential agronomical use and the nutritional and technological implications, is becoming important to strategies for improving human nutrition. In this context, we studied the accumulation of Zn and Fe in grains, considering potential uptake and translocation kinetics, photoassimilate production and deposition, and related yields, in grains of cv. Roxo produced under controlled-environment conditions and used thereafter in field trials. The metabolic plasticity of this wheat genotype grown under controlled-environment conditions allowed a 10- and 4-fold enhancement in accumulation of Zn and Fe in the grains after nutrient supplementation with a 5-fold concentrated Hoagland solution (5S), after two generations. Moreover, when these seeds were sown under field conditions and the resulting plants supplemented with or without Zn and Fe, the accumulation of these nutrients decreased within the next two generations. Such field seeds obtained without further Zn and Fe supplementation (with nitrogen only; F_3(S) and F_4(S)) maintained enhanced levels of Zn (∼400%) and Fe (40–50%) compared with the initial seeds. If Zn and Fe supplement was given to the plants germinated from F_2(5S), the subsequent F_3(5S) and F_4(5S) seeds maintained the Zn increase (∼400%), whereas a further enhancement was observed for Fe, to 75% and 89%, respectively. Toxic limits were not reached for photosynthetic functioning. Even under the highest Zn and Fe supplement dose given to the F_3(5S) plants, there was only a slight effect on photosystem II photochemical performance; in fact, enhanced net photosynthesis values were observed. In conclusion, within this experimental design, Zn and Fe biofortification can be obtained without toxicity effects on photosynthetic performance and with negligible modifications to grain texture and nutritional value (protein quality and contents as well as fatty acids).

Understanding how complexes with amino acids in soil solution affect plant zinc (Zn) uptake may aid in optimising plant Zn nutrition. We investigated the influence of histidine and glycine in nutrient solution on apoplastic and symplastic uptake and root-to-shoot translocation of Zn in a triticale (×Triticosecale cv. Elinor) and a bread wheat cultivar (Triticum aestivum cv. Back Cross Rushan). Six-week-old seedlings of the two cultivars were transferred to a nutrient solution containing 20 µm Zn, to which 50 µm histidine, 50 µm glycine or no amino acids were added. Control plants were transplanted to nutrient solution with no Zn or amino acids. Higher concentrations of Zn were found in root and shoots of wheat and triticale plants supplied with Zn than in the control plants without Zn supply. Among the treatments with Zn supply, histidine enhanced, whereas glycine reduced, symplastic root Zn concentration in bread wheat. Both amino acids decreased the symplastic root Zn concentration but had no effect on apoplastic Zn in triticale. Both amino acid treatments also reduced Zn concentrations in the xylem sap of the two plant species compared with the treatment with Zn addition only. In bread wheat, the effect was stronger for glycine than for histidine; in triticale, it was the same for both amino acids. The concentration of Zn in xylem sap was always greater in wheat than in triticale. Addition of histidine to the nutrient solution increased the total amount of shoot Zn in triticale but not in bread wheat, compared with the treatment with Zn addition only, whereas glycine had no significant effect on total shoot Zn in either of the plant species. The results show that histidine, but not glycine, can enhance Zn uptake and translocation into the aboveground parts of triticale. We suggest that this ability of histidine was due to the formation of strong complexes with Zn.

Following the first morphological and taxonomic inventory of Portuguese wheat in 1933, an archival collection of representative varieties has been maintained, replanted and documented by the National Institute of Agricultural and Veterinary Research (INIAV), specifically by its division formerly known as the National Station for Plant Improvement (ENMP-Elvas, now INIAV-Elvas). The INIAV-Elvas wheat collection has always been an invaluable asset in studies of agronomic and/or genetic development of wheat lines, as well as providing a frame of reference for the nutritional evolution of Portuguese wheat crops. This work addresses the status of selenium (Se) in a pool of 46 accessions of bread wheat. Special attention is paid to the (low) levels of Se, for which wheat acts as an important source in human diets, with a view to curbing its deficiency in Portuguese cultivars through biofortification strategies. All grain samples were irradiated at the Portuguese Research Reactor, and total Se was determined through cyclic neutron activation analysis. Our results indicate that the best candidates for an improvement of Se contents in mature grains are cvv. Ideal, Ribeiro (b) and Ribeiro (a), and the worst candidates are cvv. Restauração, Galego Rapado and Rieti.

This study concerned the effect of different intercropping systems (alternating rows and alternating strips) of maize and soybean compared with single cropping, in combination with different fertilisers (biofertiliser, organic fertiliser, and urea) on the potential availability of magnesium (Mg), iron (Fe) and zinc (Zn) from grain, through their ratio with phytate (as inhibitor) and β-carotene (as promoter). The higher grain yield and land equivalent ratio obtained under alternating rows   biofertiliser treatment demonstrated the improved ability of crops in close proximity for better utilisation of existing agro-ecological conditions. Alternating rows   organic fertiliser decreased the molar ratios phytate : β-carotene, phytate : Fe, phytate : Mg and phytate : Zn, indicating increased availability of the mineral elements in both crops. However, alternating strips   organic fertiliser contributed mostly to an increase in β-carotene, Mg, Fe and Zn concentrations in soybean. Increased grain yield of both crops was followed by decrease in β-carotene and increase in phytate, particularly in maize. In soybean, β-carotene could be considered as the main contributor to Fe availability. Accordingly, cropping in alternating rows or strips, combined with biofertilisers, could serve as fortification measures for improved nutritional quality of maize and soybean grain, without grain yield losses.

There is increasing interest in the hydroponic technology to produce leafy vegetables for ready-to-eat salads. Optimisation of the growing system can lead to higher yield and/or improved nutritional value of the product. Selenium (Se) is an essential element for animal and humans, with quite a narrow range between deficiency and toxicity, whereas it is assumed beneficial for plants. In the present study, two cultivars (Gala and Baron) of corn salad (Valerianella locusta (L.) Laterr.) were used to test the possibility to increase Se content in the edible parts (leaves). Effects on yield, nitrate content, and accumulation of sulfur (S) and S-containing amino acids and Se and Se-containing amino acids were studied. Results showed that corn salad tolerates selenate (Na₂SeO₄) concentrations ranging from 10 to 40 µm in the nutrient solution, with plants accumulating Se at levels compatible with the need in human diets at 10 µm selenate. Se-treated plants showed some benefits with respect to a decrease of nitrate concentration and increase of pigment contents (chlorophylls and carotenoids). At 10 µm selenate, Se-cysteine and Se-methionine were produced, without affecting non-protein thiols or cysteine and methionine contents. At the higher Se supply, sulfate accumulated in the leaves with a parallel decrease in the amount of S-amino acids and a rise in the relative amount of Se-amino acids. Based on the chemical analyses, cv. Gala showed better tolerance than cv. Baron to moderate selenate supply (40 µm).

Warming trends involve two agronomically relevant aspects: a gradual increase in long-term mean temperature with the primary effect of shifting phenological patterns, and an increasing incidence of heat waves. Depending on timing, intensity and duration, heat can reduce crop growth and disrupt reproduction. Agronomic and breeding adaptations to elevated temperature have been listed but there is an overall lack of frameworks for systematic analysis. This paper provides agronomic and physiological background for the quantitative assessment of spatial patterns of the thermal regimes for wheat, barley, canola, field pea and chickpea. First, we revise the notion that Australian agriculture is ‘European’ and ill-adapted to the local environments. By showing that Australian agriculture in the southern and western regions is rather Levantine, we advance a more accurate and relevant framework to the thermal regimes of winter crops. Second, we outline the direct and indirect effects of temperature on crop traits and highlight the limitations of different approaches to investigate crop responses to temperature. This is important to make explicit the assumptions of studies dealing with crop responses to temperature; for example, indirect effects of temperature on crops mediated by effects on weeds, pathogens or herbivores could be important. Third, we compare the cardinal temperatures (including base, optimal, and critical thresholds) of our target crops. Cardinal temperatures respond to both natural and agronomic selection and are relevant for crop adaptation. Fourth, we develop a conceptual framework to assess thermal effects on crop yield and adaptive practices and traits, based on the notions of yield being a primary function of seed number, the species-specific critical window for the determination of seed number, and two complementary perspectives involving the photothermal quotient and crop growth rate in the critical window. The framework accounts for both aspects of warming: non-stressful elevated temperature and heat stress. Testable propositions are advanced that inform future research on crop adaptation to elevated temperature.

The dynamics of soil phosphorus (P) fractions were investigated, in the rhizosphere of fababean (Vicia faba L.) and maize (Zea mays L.) grown in calcareous and acid soils. Plants were grown in a mini-rhizotron with a thin (3 mm) soil layer, which was in contact with the root-mat, and considered as rhizosphere soil. Hedley sequential fractionation was used to evaluate the relationship between soil pH and P dynamics in the rhizosphere of fababean and maize. Soil pH influenced the dynamics of P fractions in both calcareous and acid soils. Fababean and maize roots decreased rhizosphere pH by 0.4 and 0.2 pH units in calcareous soil, and increased rhizosphere pH by 1.2 and 0.8 pH units in acid soil, respectively, compared with the no-plant control. The acid-soluble inorganic P fraction in the rhizosphere of calcareous soil was significantly depleted by fababean, which was probably due to strong rhizosphere acidification. In contrast, maize had little effect on this fraction. Both fababean and maize significantly depleted the alkali-soluble organic P fractions in calcareous soil, but not in acid soil. Fababean and maize utilised different P fractions in soil, which was partly due to their differing abilities to modify the rhizosphere. This study has decoupled successfully the effects of chemically induced pH change from plant growth effects (such as mineralisation and P uptake) on P dynamics. The effect of soil pH on plant exudation response in P-limited soils has been demonstrated in the present study.

Biserrula is an annual pasture legume endemic to the Mediterranean basin and has been recently domesticated for use in Mediterranean environments in southern Australia. Over the past 10 years the species has been associated with isolated cases of what appears to be a primary photosensitisation in sheep that graze green pastures in winter and spring. Whole-top samples of biserrula pasture were taken from a range of farmers’ paddocks over 2 years (including paddocks where photosensitisation had been observed) and methanolic extracts were screened by high-performance liquid chromatography and liquid chromatography coupled to mass spectrometry for known primary photosensitising compounds belonging to the classes furanocoumarins and dianthrones. None of these were detected. Pyrrolizidine alkaloids were also not detected and this supports the view that a secondary photosensitisation is not involved. Chlorophyll profiles were relatively unchanged between samples and this suggested that chlorophyll metabolites are unlikely to be responsible for a primary photosensitisation. A series of luteolin and apigenin mono- and diglycosides were identified in the extracts, but these are not regarded as photosensitising compounds. Further work is required to establish the photosensitising agent(s) in biserrula.

With the aim of increasing peanut production in Australia, the Australian peanut industry has recently considered growing peanuts in rotation with maize at Katherine in the Northern Territory—a location with a semi-arid tropical climate and surplus irrigation capacity. We used the well-validated APSIM model to examine potential agronomic benefits and long-term risks of this strategy under the current and warmer climates of the new region. Yield of the two crops, irrigation requirement, total soil organic carbon (SOC), nitrogen (N) losses and greenhouse gas (GHG) emissions were simulated. Sixteen climate stressors were used; these were generated by using global climate models ECHAM5, GFDL2.1, GFDL2.0 and MRIGCM232 with a median sensitivity under two Special Report of Emissions Scenarios over the 2030 and 2050 timeframes plus current climate (baseline) for Katherine. Effects were compared at three levels of irrigation and three levels of N fertiliser applied to maize grown in rotations of wet-season peanut and dry-season maize (WPDM), and wet-season maize and dry-season peanut (WMDP). The climate stressors projected average temperature increases of 1°C to 2.8°C in the dry (baseline 24.4°C) and wet (baseline 29.5°C) seasons for the 2030 and 2050 timeframes, respectively. Increased temperature caused a reduction in yield of both crops in both rotations. However, the overall yield advantage of WPDM increased from 41% to up to 53% compared with the industry-preferred sequence of WMDP under the worst climate projection. Increased temperature increased the irrigation requirement by up to 11% in WPDM, but caused a smaller reduction in total SOC accumulation and smaller increases in N losses and GHG emission compared with WMDP. We conclude that although increased temperature will reduce productivity and total SOC accumulation, and increase N losses and GHG emissions in Katherine or similar northern Australian environments, the WPDM sequence should be preferable over the industry-preferred sequence because of its overall yield and sustainability advantages in warmer climates. Any limitations of irrigation resulting from climate change could, however, limit these advantages.

Sugarcane (Poaceae) has not undergone any commercial selection based upon seed characteristics. As the plant is grown from vegetative cuttings and the stalk harvested for its sucrose content, relatively little is known about its seed compared with other grass crops. The seeds of sugarcane were small, 1.8 × 0.8 mm, and the embryo comprised about one-third of the seed volume. Among the samples analysed, the seed contained on average 37%, 20% and 10% of the fresh weight as starch, protein and lipid, respectively. Histochemical staining showed that the starch was confined to the endosperm and the lipid to the embryo and aleurone layer. Protein was found in the embryo, endosperm and aleurone layer. There were small but significant differences between the sources of sugarcane seed. The wild relative S. spontaneum had significantly less starch than the commercial hybrid sugarcane seed. The lipid content was higher for sugarcane seed than for the seeds of many other grasses, possibly because of the high ratio of lipid-containing embryo to endosperm. Following artificial ageing, the observed decline in seed viability was not closely reflected by any significant changes in composition, although protein and sugars were reduced after 168 h. These results contribute to our understanding of the sexual reproductive biology of sugarcane, which is important for the science-based environmental risk evaluation of the release of genetically modified sugarcane.

The nutritional quality of lucerne (alfalfa, Medicago sativa L.) plants correlates positively with the presence of multifoliolate (MF) leaves. Using phenotypic recurrent selection, we developed populations with an increased percentage of MF expression from 6.7% in the original population (C0) to 77.7% in the fourth cycle (C4). The effect of selection on genetic diversity within and among populations was evaluated. The populations C0 and C4 were represented by 40 plants genotyped by using 25 simple sequence repeats (SSR). The number of alleles per locus was large in both C0 and C4, averaging 6.28. The within-population genetic diversity (H_E) overall estimation was 0.723 for C0 and 0.726 for C4, the absence of significant difference between the two populations indicating that the genetic diversity was as large in C4 as in C0. The Nei’s population differentiation (G_ST) overall estimation was 0.013, meaning that only 1.3% of the total genetic diversity was between populations and 98.7% was within populations. An efficient selection process was conducted without any increase in inbreeding or genetic drift.

Field and glasshouse experiments confirmed the occurrence of boron (B) deficiency in subterranean clover (Trifolium subterraneum L.) pasture in eastern Victoria. Diminished productivity was linked to the small-seededness of clover and the poor effectiveness of clover root-nodule bacteria (rhizobia, Rhizobium leguminosarum bv. trifolii). Productivity, especially of clover and clover seed, increased following applications of up to 6 kg B ha^–1 (P < 0.001). The response was delayed, occurring several years after the initial application of B, unless the land was resown with fresh clover seed inoculated with an effective strain of rhizobia.

B deficiency in the nodulated legume induced conditions within the plant and or its rhizobia that led to impaired nitrogen (N₂) fixation. Glasshouse research indicated that populations of soil-borne rhizobia taken from B-deficient soils were poorly effective in N₂ fixation and that rhizobia from soils growing subterranean clover cv. Leura were significantly less effective (P < 0.05) than rhizobia from a soil growing cv. Mt Barker.

Additionally, subterranean clover seed generated in B-deficient soils was at least one-third smaller than the seed of commercial seed but responded to inoculation with effective rhizobia. This indicated that any symbiotic malfunction of clover from B-deficient soils was not due to an inability to respond to nitrogen per se. On the other hand, cv. Leura from B-deficient soils fixed significantly less N₂ than commercial cv. Leura when each was inoculated with rhizobia from B-deficient soils.