Context. In order to identify best crop genotypes for recommendation to breeders, and ultimately for use in breeding, evaluation is usually conducted in field trials across a range of environments, known as multi-environment trials. Increasingly, many breeding traits are measured over time, for example with high-throughput phenotyping at different growth stages in annual crops or repeated harvests in perennial crops.

Aims. This study aims to provide an efficient, accurate approach for modelling genotype response over time and across environments, accounting for non-genetic sources of variation such as spatial and temporal correlation.

Methods. Because the aim is genotype selection, genetic effects are fitted as random effects, and so the approach is based on random regression, in which linear or non-linear models are used to model genotype responses. A method for fitting random regression is outlined in a multi-environment situation, using underlying cubic smoothing splines to model the mean trend over time. This approach is illustrated on six wheat experiments, using data on grain-filling over thermal time.

Key results. The method correlates genetic effects over time and environments, providing predicted genotype responses while incorporating spatial and temporal correlation between observations.

Conclusions. The approach provides robust genotype predictions by accounting for temporal and spatial effects simultaneously under various situations including those in which trials have different measurement times or where genotypes within trials are not measured at the same times. The approach facilitates investigation into genotype by environment interaction (G × E) both within and across environments.

Implications. The models presented have potential to increase accuracy of predictions over measurement times and trials, provide predictions at times other than those observed, and give a greater understanding of G × E interaction, hence improving genotype selection across environments for repeated-measures traits.

Context. Cadmium (Cd) is a toxic metal for both plants and humans. Wheat grown on Cd-contaminated soils may accumulate toxic levels of Cd in grains.

Aim. This study aimed to compare soil zinc (Zn) application and seed Zn-priming for decreasing grain Cd concentration in standard and Zn-biofortified wheat cultivars grown on Cd-spiked soil.

Methods. Standard (Jauhar-2016) and Zn-biofortified (Zincol-2016) wheat cultivars were grown in pots filled with Cd-spiked soil (8 mg Cd kg⁻¹). The tested Zn treatments were un-primed, hydro-primed, and Zn-primed seeds with and without soil Zn application at 8 mg kg⁻¹.

Key results. Zinc treatments significantly mitigated the toxic effects of Cd on the growth and physiological parameters of both cultivars. As compared to control, all Zn treatments significantly increased Zn and decreased Cd concentration in grains of the cultivars. On average, the maximum increase in grain Zn concentration over control was approximately 36% with Zn-priming + soil Zn. The same treatment, as compared to control, decreased grain Cd concentration by 42% in Zincol-2016 and 35% in Jauhar-2016. Grain Cd concentration was within the permissible level (≤0.2 mg kg⁻¹) in Jauhar-2016 at all Zn treatments and in Zincol-2016 at Zn-priming + soil Zn.

Conclusion. Soil Zn application, seed Zn-priming, and their combination were effective in decreasing grain Cd accumulation in wheat grown on Cd-contaminated soil.

Implication. Zinc treatments, especially the combination of soil Zn application and seed Zn-priming, should be recommended for wheat grown on Cd-contaminated soil.

Context. Morphometric digital analysis of plant seeds enables taxonomic discrimination of species based on morpho-colorimetric traits, and may be used to classify genotypes of wheat (Triticum aestivum L.).

Aims. This study was focused on the isolation and classification of cultivars and landraces of Iranian wheat based on morpho-colorimetric traits, and the prediction of yield and seedling vigour based on these traits.

Methods. In total, 133 wheat genotypes (91 native landraces and 42 cultivars) were evaluated by alpha lattice design in two crop years (2018–19 and 2019–20) under rainfed and conditions. After seed harvesting, 40 morpho-colorimetric traits of wheat seeds were measured by imaging. Seed colour, morphometric seed, seed vigour and yield were also assessed.

Key results. Using linear discriminant analysis based on morpho-colorimetric traits, wheat cultivars and landraces were separated with high validation percentage (90% in well-watered and 98.6% in rainfed conditions). Morpho-colorimetric traits L, Whiteness index, Chroma, a, Feret and Rectang were found to be the most discriminant variables in the rainfed field. In analysis based on seed colour according to descriptors of the International Union for the Protection of New Varieties of Plants and International Board for Plant Genetic Resources, wheat genotypes were classified into four groups with high accuracy by using linear discriminant analysis. Specifically, 97.3% could be identified as yellow and 99.7% as medium-red wheat groups.

Conclusions. Our observations suggest that seed digital analysis is an affordable and valuable approach for evaluating phenotypic variety among a large number of wheat genotypes. Morphometric analysis of cultivars and native populations can provide an effective step in classifying genotypes and predicting yield and seedling vigour.

Implications. Morphometric databases will help plant breeders when selecting genotypes in breeding programs.

Context. In the malting industry, the low protein content of barley grains is a major issue. A useful strategy to overcome this problem is to complement the initial fertilisation with a foliar application of nitrogen (N) near anthesis.

Aims. This study aimed to advance knowledge of the metabolic adjustments displayed by plants grown under common management practices in response to foliar N fertilisation at anthesis.

Methods. Field experiments with two different rates of foliar N application near anthesis were performed at three commercial sites under the common practice of each farmer.

Key results. Grain protein content increased upon foliar fertilisation in all sites without affecting leaf senescence or N remobilisation efficiency. Barley plants also showed a rapid assimilation of the N applied at anthesis, increasing the leaf N organic pools and the global phloem amino acid mobilisation during grain filling. These results could be attributed to the increase in the gene expression of glutamine synthetase 1 and two amino acid transporters (HvAAP6 and HvAAP7).

Conclusions. Foliar N applied was rapidly assimilated and exported with high efficiency to the grain with no negative impact over the contribution of N from vegetative organs. Furthermore, phloem N contribution was shown to be of major importance for grain protein content.

Implications. Foliar fertilisation near anthesis is an efficient strategy to correct grain protein content to meet maltsters’ requirements because it did not affect pre-assimilated N remobilisation, and was useful under the different nutrient availabilities explored here (N sufficiency, N deficiency and sulfur deficiency).

Context. Photosynthetic electron transport and apparatus are highly susceptible to abiotic stressors during photosynthesis. Hordeum jubatum L. is an ornamental grass with excellent salt tolerance, used for soil improvement and ecological restoration in Northeast China. However, the comparative effects of salt, alkali and drought conditions on the photosynthetic apparatus of H. jubatum under uniform water potential are little known.

Aims. We explored the photosynthetic response of H. jubatum to uniform levels of water potential stress induced by three different stressors: salt, alkali and drought.

Methods. Seedlings of H. jubatum were irrigated with three concentrations of NaCl, NaHCO₃ and PEG-6000 to induce water potentials of −0.21, −0.47 and −0.82 MPa. Transient fluorescence of chlorophyll a in the seedlings was measured, and JIP-test parameters were obtained.

Key results. Lower values of J–I phase fluorescence intensity and appearance of a K-band under stress treatments indicated restricted electron transfer from the oxygen-evolving complex in the donor of photosystem II. In addition, the values of ΔI-band and parameters M_O and N increased, whereas those of S_m, ϕ_Eo and ψ_O decreased, indicating interruption of electron flow between electron acceptors pheophytin and NADP⁺. Serious adverse effects of alkali stress on the acceptors were observed; the low water potential induced by NaHCO₃ damaged the thylakoid membrane on the chloroplast, resulting in increased degradation of D1 protein.

Conclusions. The results suggest that H. jubatum seedlings have greater tolerance to salt and drought stress, but are highly sensitive to alkali stress in the photosynthetic system.

Implications. This study provides physiological information for the successful cultivation of H. jubatum under adverse environment conditions.

Context. With the widespread use of transgenic soybeans (Glycine max (L. ) Merr.), their nutritional assessment for human food and animal feed is an important aspect of safety evaluation. WRINKLED 1 (WRI1) is a transcriptional activator of genes involved in fatty acid synthesis.

Aims. We aimed to evaluate the effect of overexpression of GmWRI1a in soybean on the nutritional profile of soybean seeds.

Methods. Using molecular biology techniques, we identified three transgenic soybean lines stably overexpressing GmWRI1a (GmWRI1a-OE). We quantified the nutritional and anti-nutritional components in seeds of GmWRI1a-OE and wild-type (DN50) soybean, and compared them on the basis of the principle of substantial equivalence.

Key results. The GmWRI1a and Bar genes were stably inherited in the three GmWRI1a-OE lines, and GmWRI1a protein content was higher in transgenic soybean seeds than in wild-type seeds. Overexpression of GmWRI1a resulted in changes in fatty acid composition, a significant increase in oil content, and a significant decrease in stachyose content in seeds. Contents of other nutritional components (proximates, amino acids and isoflavones) and anti-nutritional factors (phytic acid, trypsin inhibitors and raffinose) in seeds were not significantly different between the wild-type and GmWRI1a-OE lines.

Conclusions. Contents of nutritional and anti-nutritional components of GmWRI1a-OE seeds were all within the reference ranges reported for commercially available soybeans and, therefore, are substantially equivalent to those of wild-type seeds.

Implications. GmWRI1a-OE soybean seeds are a high-quality product for health-conscious consumers.

Faba bean (Vicia faba L.) is an important component of cropping systems in cool, arid environments. However, no review has specifically focused on the quantitative sensitivity of physiological processes in faba bean to low temperature and water deficits. The objective of this review was to examine published functional relationships between physiological activity and these environmental variables. Among faba bean genotypes, temperature generally resulted in a consistent linear response in plant ontogeny and leaf area development. By contrast, nitrogen fixation exhibited a sharp threshold response to temperature such that at temperatures below ~13.5–15°C faba bean had virtually no nitrogen fixation activity. This inability to fix nitrogen under cool temperatures is likely to be a major weakness for faba bean in cool-season production systems. Water deficit also had a large impact on the physiology of faba bean. Ontogeny was generally shortened when plants were subjected to drought, resulting in major yield decreases. Genotypic differences within faba bean have been identified for initiation of partial stomata closure at high soil-water content, resulting in possible soil-water conservation in the field. Also, differences among genotypes have been identified in the sensitivity of nitrogen fixation activity to water deficits. Finally, collectively the reviewed functional relationships have been applied to simulation analysis of the geospatial impact of irrigation regimes and of sowing date for faba bean production. These geospatial studies offered insights on options to improve faba bean management.

Context. Tall bunch-type tropical forage grasses are known for their rapid (true) stem elongation late in the regrowth cycle, even during the vegetative phase.

Aims. This study aimed to evaluate the stem and pseudostem growth pattern of ‘Mombaça’ guineagrass [Megathyrsus maximus (Jacq.) BK Simon & SWL Jacobs] grown in field conditions and how this relates to its high biomass accumulation during long regrowth cycles.

Methods. A guineagrass field was managed from December 2017 to January 2019, in three regrowth cycles of 10, 14 and 12 weeks duration. Individual tillers were assessed weekly to measure stem, pseudostem and leaf elongation, leaf appearance; and angle of insertion of the leaves. Aboveground biomass samples were taken weekly for biomass accumulation and leaf area index assessment.

Key results. At the beginning of each regrowth cycle, the pseudostem elongated while the stem length remained constant. Subsequently, the pseudostem length reached a plateau, while the stem length increased at a constant rate. Because of a positive relationship between pseudostem and leaf laminae lengths, the long pseudostem ensured the formation of long leaves in tall tillers and positive net leaf elongation in long regrowth cycles.

Conclusions. The high biomass accumulation reflected the continuous positive net leaf elongation by the tillers and was underpinned by the younger leaves being more erect than the older ones, allowing for lower self-shading of the older leaves and greater leaf tissue retention.

Implications. The high production of tropical forage grasses in late regrowth should be utilised with caution, as it is underpinned by stem elongation and meristem elevation.

Context. Red clover (Trifolium pratense L.) is an important legume forage in temperate agricultural zones. Evaluation of self- and cross-pollination fertility is important for setting up an effective breeding-program scale. However, the outcrossing rate of red clover under open-pollination conditions is not certain. Development of a reliable and time-saving marker system is needed to quantify and characterise outcrossing rates.

Aim. We aimed to develop a duplex PCR-based protocol based on a genome-wide simple sequence repeat (SSR) screen, and to determine the outcrossing rate of red clover under open-pollination environments.

Methods. We screened 209 SSR markers with pooled DNA samples of 60 plants from 20 red clover accessions, and selected 185 SSR markers that produced clear scorable bands for testing with 24 individual DNA samples to determine polymorphism. We selected 70 primer pairs, and then assembled a core set of 24 loci into 12 sets of duplex markers, which were used for outcrossing behaviour analysis of 60 maternal parents and their respective 22 half-sib progenies.

Key results. Mean polymorphic information content (PIC) for the 70 markers was 0.490 (range 0.117–0.878). Minimum, mean and maximum PIC values for the 24 markers constituting the 12 duplexes were 0.226, 0.594 and 0.781, respectively. The outcrossing rate was identified as 99.4% for red clover in a natural environment.

Conclusion. We successfully developed a duplex SSR-based PCR protocol consisting of 24 markers. This SSR system was applied to determine the outcrossing rate of red clover in a natural environment.

Context. Continuous grazing in extensive grassland creates grazed and ungrazed patches, which are important for ecosystem service delivery. One possibility for optimising ecosystem services is to target a defined compressed sward height, which can be measured with rising plate meters supplied with internal global navigation satellite system (GNSS) receivers.

Aims. We assessed the ability of a modern rising plate meter to map long-term patch structure in extensively grazed grassland as a means to improve estimation of phytodiversity at paddock scale as a paramount ecosystem service.

Methods. The patch class proportions obtained from interpolating the georeferenced compressed sward height values were used to calculate phytodiversity indicators at paddock scale as determined by dry-weight ranking. In addition, a modern rising plate meter with internal GNSS receiver was compared with an established one without GNSS receiver.

Key results. The mapping of the patch classes revealed decreasing proportions of tall patches with increasing stocking intensity. Phytodiversity at paddock scale depended on the proportions of respective patches, highlighting the importance of accurate mapping of patches for ecosystem service assessment.

Conclusions. The new rising plate meter extends the utilisation of compressed sward height measurements into a spatial context. Patch size, spatial distribution of patches within a paddock and spatial clustering of patches, as well as repeated mapping over time, can be utilised to detect change and monitor long-term management schemes without the need for sophisticated remote-sensing applications.

Implications. The combination of the new rising plate meter and dry-weight ranking extends grazing management towards biodiversity monitoring in an easy-to-learn approach.