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Background and Aims Some Caryophyllales species accumulate abnormally large shoot sodium (Na) concentrations in non-saline environments. It is not known whether this is a consequence of altered Na partitioning between roots and shoots. This paper tests the hypotheses (1) that Na concentrations in shoots ([Na]shoot) and in roots ([Na]root) are positively correlated among Caryophyllales, and (2) that shoot Na hyperaccumulation is correlated with [Na]shoot/[Na]root quotients. Methods Fifty two genotypes, representing 45 Caryophyllales species and 4 species from other angiosperm orders, were grown hydroponically in a non-saline, complete nutrient solution. Concentrations of Na in shoots and in roots were determined using inductively coupled plasma mass spectrometry (ICP-MS). Key Results Sodium concentrations in shoots and roots were not correlated among Caryophyllales species with normal [Na]shoot, but were positively correlated among Caryophyllales species with abnormally large [Na]shoot. In addition, Caryophyllales species with abnormally large [Na]shoot had greater [Na]shoot/[Na]root than Caryophyllales species with normal [Na]shoot. Conclusions Sodium hyperaccumulators in the Caryophyllales are characterized by abnormally large [Na]shoot, a positive correlation between [Na]shoot and [Na]root, and [Na]shoot/[Na]root quotients greater than unity.

Summary • The question ‘are fragmented wild populations of raspberry adaptively differentiated from each other and from cultivated forms of the same species?’ is addressed here. • Plants collected from the coast, where commercial raspberries are grown, northwards by 49 km to an altitude of 600 m in Tayside, Scotland, were cultured in two common environments. Twenty phenotypic traits were recorded over 2 yr, on vegetative primocanes and then the single dominant floricane retained for year 2. A novel approach is presented for selecting traits that best discriminate between individuals using principal coordinate analysis. Phenotypic variation among accessions was then quantified using principal coordinate analysis followed by principal component analysis. • A consistent north–south trend was found. Plants from northern sites were shorter, bushier with less lateral growth and fewer flowers per lateral on the dominant fruiting cane. Plants from southern sites produced few, tall primocanes with greater cane diameters, lateral growth and flowering. The results were consistent across test environments. • The results confirm substantial, adaptive differentiation between populations and suggest a limited effect of cultivation on wild forms.

The effects of phosphorus and zinc applications on phosphorus and zinc concentrations in plants grown in different soil types have rarely been investigated. The aim of this study was to evaluate the effects of different soil types and phosphorus and zinc addition on growth and mineral element composition of red cabbage (Brassica oleracea var. capitata L. cv. Red Drumhead). Plants were grown for six weeks in three different soils (a freely drained Cambisol, an imperfectly drained Cambisol, and a Stagnosol) in a glasshouse. Each soil was amended with one of 25 combinations of phosphorus and zinc fertiliser. Soil characteristics, growth, and mineral element concentrations in shoots were assessed. Soil type significantly affected shoot growth and concentrations of phosphorus, zinc, potassium, calcium, magnesium and manganese, but not iron concentration of red cabbage. Across soils, the observed responses were attributed to soil phosphorus, potassium, calcium, magnesium, and sulphur concentrations, organic matter content, and mineral composition, mainly kaolinite and plagioclase. Soil type effects on mineral element composition of red cabbage could have important implications for increasing mineral element concentration in crops to alleviate mineral element deficiencies in human diets.

Shoot zinc (Zn) concentration in Brassica oleracea is affected by soil Zn and phosphorus (P) supply. Most problematic is the negative impact of P fertilizers on Zn concentrations in crops, which makes balancing yield and mineral quality challenging. To evaluate early molecular mechanisms involved in the accumulation of large shoot Zn concentrations regardless of the P supply, two B. oleracea accessions differing in root architecture and root exudates were grown hydroponically for two weeks with different combinations of P and Zn supply. Ionome profiling and deep RNA sequencing of roots revealed interactions of P and Zn in planta, without apparent phenotypic effects. In addition, increasing P supply did not reduce tissue Zn concentration. Substantial changes in gene expression in response to different P and/or Zn supplies in roots of both accessions ensured nutritionally sufficient P and Zn uptake. Numerous genes were differentially expressed after changing Zn or P supply and most of them were unique to only one accession, highlighting their different strategies in achieving nutrient sufficiency. Thus, different gene networks responded to the changing P and Zn supply in the two accessions. Additionally, enrichment analysis of gene ontology classes revealed that genes involved in lipid metabolism, response to starvation, and anion transport mechanisms were most responsive to differences in P and Zn supply in both accessions. The results agreed with previously studies demonstrating alterations in P and Zn transport and phospholipid metabolism in response to reduced P and Zn supply. It is anticipated that improved knowledge of genes responsive to P or Zn supply will help illuminate the roles in uptake and accumulation of P and Zn and might identify candidate genes for breeding high-yield-high-Zn brassicas.

Crop genotypes that make best use of potassium (K) fertilizers can promote agricultural sustainability. However, screening germplasm collections for responses to K fertilizers is often laborious and expensive. To reduce costs, the number of K fertilizer treatments required to identify better genotypes should be minimized. This might be achieved by exploiting the mathematical relationships between biomass, plant K content, and K supply. This study employed 14 barley (Hordeum vulgare L.) genotypes growing in a hydroponics system that allowed the K supply to roots to be controlled through the K concentration in a flowing solution. It sought to determine the minimal number of treatments required to model the relationships between (a) shoot biomass and K supply, (b) plant K content and K supply, and (c) shoot biomass and plant K content. The relationships between (a) shoot biomass and K supply and (b) plant K content and K supply for any given genotype could be fitted by Michaelis–Menten equations and ...

The diets of many people lack sufficient zinc (Zn). This article investigates the production of potato (Solanum tuberosum L.) crops with greater tuber Zn concentrations to increase dietary Zn intakes. Field experiments were undertaken to increase Zn concentrations in potato tubers using foliar Zn fertilisers. Foliar Zn fertilisers increased tuber Zn concentrations but excessive applications reduced tuber yield in all four potato genotypes studied. Zinc oxide and zinc sulphate were more effective than zinc nitrate as foliar fertilisers for increasing tuber Zn concentrations whilst maintaining yields. Foliar Zn-fertilisers increased Zn concentrations in both flesh and skin of tubers. Although Zn-biofortification had no effect on the concentrations of iron, manganese, copper, calcium, magnesium or potassium in tubers, it increased tuber phytate concentrations. Cooking reduced Zn concentrations in Zn-biofortified tubers and this effect was exacerbated by peeling. After cooking, the quotient of Zn concentrations in Zn-biofortified/non-biofortified tubers ranged from 2.36 to 3.58. Applying foliar Zn fertilisers to a preceding potato crop increased Zn concentrations in grain of a following barley crop significantly in only one out of 3 years. Foliar Zn fertilisers can increase Zn concentrations in potato tubers and, potentially, dietary Zn intakes.

Broccoli crops are produced throughout the year. They are grown under a wide range of environmental conditions, which results in large variation in the time to head initiation and in head growth after initiation. Mis-scheduling broccoli crops has financial consequences. Models to predict the harvest dates of broccoli crops allow growers to adapt their commercial strategies to maintain an appropriate supply of broccoli throughout the year in a cost-effective manner. The work described here developed models for the phenology and yields of Scottish broccoli crops using data from field trials and commercial crops that allow the prediction of harvest dates from observations or forecasts of daily temperatures and radiation. The models were validated using independent data obtained from commercial broccoli growers and used to explore the local, seasonal and year-to-year variation in the predicted harvest dates of broccoli in Scotland. The date of transplanting seedlings to the field had the largest effect on the time to harvest, although there was also considerable annual variation. Geographical location had least effect on the time to harvest.

Background Phosphorus (P) deficiency limits crop production worldwide. Crops differ in their ability to acquire and utilise the P available. The aim of this study was to determine root traits (root exudates, root system architecture (RSA), tissue-specific allocation of P, and gene expression in roots) that (a) play a role in P-use efficiency and (b) contribute to large shoot zinc (Zn) concentration in Brassica oleracea. Results Two B. oleracea accessions (var. sabellica C6, a kale, and var. italica F103, a broccoli) were grown in a hydroponic system or in a high-throughput-root phenotyping (HTRP) system where they received Low P (0.025 mM) or High P (0.25 mM) supply for 2 weeks. In hydroponics, root and shoot P and Zn concentrations were measured, root exudates were profiled using both Fourier-Transform-Infrared spectroscopy and gas-chromatography-mass spectrometry and previously published RNAseq data from roots was re-examined. In HTRP experiments, RSA (main and lateral root number and lateral root length) was assessed and the tissue-specific distribution of P was determined using micro-particle-induced-X-ray emission. The C6 accession had greater root and shoot biomass than the F103 accession, but the latter had a larger shoot P concentration than the C6 accession, regardless of the P supply in the hydroponic system. The F103 accession had a larger shoot Zn concentration than the C6 accession in the High P treatment. Although the F103 accession had a larger number of lateral roots, which were also longer than in the C6 accession, the C6 accession released a larger quantity and number of polar compounds than the F103 accession. A larger number of P-responsive genes were found in the Low P treatment in roots of the F103 accession than in roots of the C6 accession. Expression of genes linked with “phosphate starvation” was up-regulated, while those linked with iron homeostasis were down-regulated in the Low P treatment. Conclusions The results illustrate large within-species variability in root acclimatory responses to P supply in the composition of root exudates, RSA and gene expression, but not in P distribution in root cross sections, enabling P sufficiency in the two B. oleracea accessions studied.

Aims\ud Potato (Solanum tuberosum L.) has a large phosphorus (P)-fertiliser requirement. This is thought to be due to its inability to acquire P effectively from the soil. This work tested the hypothesis that early proliferation of its root system would enhance P acquisition, accelerate canopy development, and enable greater yields.\ud \ud Methods\ud Six years of field experiments characterised the relationships between (1) leaf P concentration ([P]leaf), tuber yield, and tuber P concentration ([P]tuber) among 27 Tuberosum, 35 Phureja and 4 Diploid Hybrid genotypes and (2) juvenile root vigour, P acquisition and tuber yield among eight Tuberosum genotypes selected for contrasting responses to P-fertiliser.\ud \ud Results\ud Substantial genetic variation was observed in tuber yield, [P]leaf and [P]tuber. There was a strong positive relationship between tuber yields and P acquisition among genotypes, whether grown with or without P-fertiliser. Juvenile root vigour was correlated with accelerated canopy development and both greater P acquisition and tuber biomass accumulation early in the season. However, the latter relationships became weaker during the season.\ud \ud Conclusions\ud Increased juvenile root vigour accelerated P acquisition and initial canopy cover and, thereby, increased tuber yields. Juvenile root vigour is a heritable trait and can be selected to improve P-fertiliser use efficiency of potato.

The combined application of nitrogen (N) and zinc (Zn) fertilizers is a promising agronomic strategy for the biofortification of wheat grain with Zn for human nutrition. A glasshouse experiment was carried out to assess the effects of supplying N on the uptake, translocation and accumulation of Zn in tissues of two wheat genotypes (Quartzo and BRS Parrudo) with contrasting potential for grain Zn biofortification. Winter wheat genotypes were grown to maturity in 5 cm diameter, 100 cm length tubes filled with a mixture of sand, grit and gravel (40:40:20 v/v/v) over a layer of 0.1 m3 of gravel, and supplied a full nutrient solution with low Zn (0.15 μM) or high Zn (2.25 μM) and low N (0.4 mM) or high N (4.0 mM) concentrations. High N supply increased biomass production, Zn concentration and Zn content of straw and grain in both Quartzo and BRS Parrudo. Grain Zn content more than doubled when the supplies of Zn and N were both increased from low to high in both genotypes. Quartzo had a greater grain yield than BRS Parrudo. BRS Parrudo had greater grain Zn concentration and Zn content than Quartzo. A greater N supply promoted better uptake, translocation to the shoot and accumulation of Zn within the grain. Quartzo and BRS Parrudo differed in their partitioning of biomass and Zn between tissues. It might be possible to combine the greater grain yield of Quartzo with the greater grain Zn accumulation of BRS Parrudo to deliver a greatly improved genotype for human food security.

Background: There are numerous systems and techniques to measure the growth of plant roots. However, phenotyping large numbers of plant roots for breeding and genetic analyses remains challenging. One major difficulty is to achieve high throughput and resolution at a reasonable cost per plant sample. Here we describe a cost-effective root phenotyping pipeline, on which we perform time and accuracy benchmarking to identify bottlenecks in such pipelines and strategies for their acceleration.\ud \ud Results: Our root phenotyping pipeline was assembled with custom software and low cost material and equipment. Results show that sample preparation and handling of samples during screening are the most time consuming task in root phenotyping. Algorithms can be used to speed up the extraction of root traits from image data, but when applied to large numbers of images, there is a trade-off between time of processing the data and errors contained in the database.\ud \ud Conclusions: Scaling-up root phenotyping to large numbers of genotypes will require not only automation of sample preparation and sample handling, but also efficient algorithms for error detection for more reliable replacement of manual interventions.

The prevalence of sodium (Na) “hyperaccumulator” species, which exhibit abnormally large shoot sodium concentrations ([Na]shoot) when grown in non-saline environments, was investigated among angiosperms in general and within the Caryophyllales order in particular. Shoot Na concentrations were determined in 334 angiosperm species, representing 35 orders, grown hydroponically in a non-saline solution. Many Caryophyllales species exhibited abnormally large [Na]shoot when grown hydroponically in a non-saline solution. The bimodal distribution of the log-normal [Na]shoot of species within the Caryophyllales suggested at least two distinct [Na]shoot phenotypes within this order. Mapping the trait of Na-hyperaccumulation onto the phylogenetic relationships between Caryophyllales families, and between subfamilies within the Amaranthaceae, suggested that the trait evolved several times within this order: in an ancestor of the Aizoaceae, but not the Phytolaccaceae or Nyctaginaceae, in ancestors of several lineages formerly classified as Chenopodiaceae, but not in the Amaranthaceae sensu stricto, and in ancestors of species within the Cactaceae, Portulacaceae, Plumbaginaceae,Tamaricaceae and Polygonaceae. In conclusion, a disproportionate number of Caryophyllales species behave as Na51 hyperaccumulators and multiple evolutionary origins of this trait can be identified within this order.

Summary Species diversity and abundance in weed seedbanks were measured at the beginning, and after 3 and 6 yr of the TALISMAN experiment at ADAS Boxworth, Drayton and High Mowthorpe. Fifty species were distinguished in the seedbanks of treatments comprising winter and spring rotations and full and reduced herbicide input. After 6 yr, the number of seedbank species in the main treatments ranged from 11 in the most intense to 26 in the least intense management. Principal co-ordinate analysis showed that the seedbank community diverged over time between sites and additionally between the two rotation treatments at Boxworth. Only four species were common to all sites but community-scale descriptors indicated that the change in seedbanks following reduced inputs had common features at the three sites. First, species-area relations showed a greater relative increase in number of taxa at a plot scale than in the site as a whole, indicating lower inputs encouraged the common weeds more than rare species. Second, both the mean and the standard deviation of the species-abundance distribution at 6 yr increased in response to reduced inputs. As a result, the number of species slightly more than doubled as herbicide units were reduced from four to one while the total number of seeds increased by two orders of magnitude. Some causes of seedbank change were identified: spring-germinating species tended to increase when spring cultivation was common in the rotation, while some competitive weeds had a relatively low abundance when they were targeted by herbicide. The results are discussed in relation to optimising the various functions of the seedbank.

Genetic control of germination time in oilseed rape might enable some cultivars to adapt locally as a volunteer weed or a feral plant. The heritability of withinpopulation germination characteristics was therefore investigated for the oilseed rape cultivar Martina. Two groups of seed were selected from a batch of seeds germinated at 5 °C: those germinating up to about the 20th percentile, termed early germinators, and those above the 80th percentile, viable non-germinators, which did not germinate at 5°C but did so subsequently when moved to a higher temperature. The groups of seeds were isolated, grown to flowering and the plants self-pollinated. Germination of the new seed from the two groups was then compared with seed from the original population at temperatures between 4 C and 19°C on a thermal plate. Differences between seed lots were small at 19 °C, but large below 10 C. The differences in spread of time were analysed by fitting exponential curves to the non-linear relation of 1/time on temperature for each of five percentiles, 10, 20 50, 80, and 90. The fitting procedure tested the extent to which variation within and between seed lots was caused by variation in the base temperature, the curvature of the relation and a parameter for scaling the curve between percentiles. Progeny of the early seed germinated much more rapidly than the original, and germinated completely even at low temperature. The more rapid germination was attributed to a lower extrapolated base temperature of — 2.3 °C, compared to —0.7 C for the original, and slightly greater curvature. Progeny of non-germinato r seed contained a higher proportion of viable non-germinating seed (for example, 20% germination at 4 °C, compared to 50% for the original), but the germinating seed differed only slightly from the original in time to germination. Among the germinating percentiles, both types of progeny displayed less spread in time to germination than the original seed. It was concluded that the cultivar had the potential to give rise to genetically distinct populations able to exploit different seasonal opportunities.

BACKGROUND AND AIMS Phosphorus commonly limits crop yield and is frequently applied as fertilizer; however, supplies of quality rock phosphate for fertilizer production are diminishing. Plants have evolved many mechanisms to increase their P-fertilizer use efficiency, and an understanding of these traits could result in improved long-term sustainability of agriculture. Here a mutant population is utilized to assess the impact of root hair length on P acquisition and yield under P-deficient conditions alone or when combined with drought. METHODS Mutants with various root hair phenotypes were grown in the glasshouse in pots filled with soil representing sufficient and deficient P treatments and, in one experiment, a range of water availability was also imposed. Plants were variously harvested at 7 d, 8 weeks and 14 weeks, and variables including root hair length, rhizosheath weight, biomass, P accumulation and yield were measured. KEY RESULTS The results confirmed the robustness of the root hair phenotypes in soils and their relationship to rhizosheath production. The data demonstrated that root hair length is important for shoot P accumulation and biomass, while only the presence of root hairs is critical for yield. Root hair presence was also critical for tolerance to extreme combined P deficit and drought stress, with genotypes with no root hairs suffering extreme growth retardation in comparison with those with root hairs. CONCLUSIONS The results suggest that although root hair length is not important for maintaining yield, the presence of root hairs is implicit to sustainable yield of barley under P-deficient conditions and when combined with extreme drought. Root hairs are a trait that should be maintained in future germplasm.

SUMMARY Ninety-eight soil samples were collected from cereal farms on mainland Scotland and examined for migratory plant-parasitic and predatory nematodes. Soil analysis was also carried out on each sample. Of the 25 parasitic nematode species identified Longidorus elongatus was the most frequently found and while populations were generally low, populations great enough to cause damage were detected. Populations of other plant-parasites were usually low. Individual species were unlikely to cause economic losses but their combined effect could possibly reduce yields. Analysis of the relationships between nematode species suggested that neither competition nor predation were important factors limiting population size. With few exceptions, none of the soil factors measured influenced the occurrence or abundance of the nematodes identified.

Insufficient calcium (Ca) or magnesium (Mg) in the diets of humans and animals has negative effects on health. Knowledge of the concentrations of Ca and Mg in edible crops can help inform the formulation of appropriate diets. There are large differences in shoot concentrations of both Ca ([Ca]shoot) and Mg ([Mg]shoot) between angiosperm orders. For example, relative to other angiosperms, commelinid monocot species generally have lower [Ca]shoot and [Mg]shoot; species from the Cucurbitales, Malvales and Brassicales generally have higher [Ca]shoot and [Mg]shoot; and species from the Oxalidales and Caryophyllales generally have higher [Mg]shoot but similar [Ca]shoot, which results in higher [Mg]shoot/[Ca]shoot quotients. In this paper the evolution of the combined traits of high [Mg]shoot and high [Mg]shoot/[Ca]shoot quotient in the Caryophyllales was resolved at the family level. All Caryophyllales families had high mean [Mg]shoot and [Mg]shoot/[Ca]shoot quotients, suggesting that both of these traits evolved in an ancient ancestor of all Caryophyllales families.