A cultivation of durum wheat that established in a field with soil poor in micronutrients received foliar applications at the initiation of the dough stage towards biofortifying the spikes with micronutrients. The morphology of the spike is crucial in determining grain yield, and the spikelets, the components of the inflorescence, influence each other. The number and arrangement of these spike components affect spike length, spike weight, spike chaff (the non-grain biomass in the spike), grain number per spike, grain weight per spike, and spikelet number per spike, and all contribute to final grain yield per spike. The spike’s developmental program responded to the interventions regarding the morphological traits; this response was analyzed for each spike component, and an acclimation program seemed to be activated by each intervention. Cysteine or methionine has been added as a potential enhancer of the biofortification process, and the application mixtures were coupled with selected surfactants, an organosilicon ethoxylate or an alcohol ethoxylate one, while products with targeted composition for biofortification with micronutrients have also been studied. Their effect on the developmental acclimation program of the treated spike is presented and discussed. The action of this program provided grains of similar weight, regardless of the intervention.

This article comments on: D’Hooghe P, Kopriva S, Avice JC, Trouverie J. 2025. Tuning of sulfur flow and sulfur seed metabolism in oilseed rape under sulfate-limited conditions. Journal of Experimental Botany 76, https://doi.org/10.1093/jxb/eraf028

A two-year field experiment (2022–2023) was carried out to investigate the impact of different sowing periods (spring and winter) and nitrogen levels (0, 30, 60 kg/ha) on the phytoextraction potential of flax. The study site is characterized by high concentrations of heavy metals (Cd, Ni, Cu, Pb, Zn) and belongs to the Mediterranean climate type. Flax (var. Calista) was sown in the spring of 2022 and in the winter of 2023, following a split plot experimental design with three rep-lications, and applying low-input practices. Results showed that spring-sown flax produced short-er but thicker plants with significantly higher biomass (5.27 tn ha-1) when treated with 30 kg ha-1 N compared to winter-sown (2.30 tn ha-1) when treated with 60 kg ha-1 N. The concentration of contaminants in the aerial biomass varied according to metal type and sowing period. The higher biomass production in spring resulted in a higher quantity of heavy metals being removed from the soil, making flax a promising crop for phytoextraction purposes, especially in soils contami-nated with multiple heavy metals.

The aim of this study was to assess the phytoremediation potential of fiber flax (Linum usitatissimatum L., var. Calista) cultivated in a soil contaminated with multiple metals, under real field conditions. A two-year (2022 and 2023) field experiment was conducted in a site contaminated with elevated concentrations of Cd, Ni, Cu, Pb, and Zn due to mining and metallurgical activities. Three different nitrogen fertilization levels were tested (N0: 0 kg N ha−1, N1: 30 kg N ha−1, N2: 60 kg N ha−1), and both spring and winter sowings were conducted. At full maturity, growth parameters and yields were measured. The phytoremediation potential of flax was assessed in terms of the metal concentrations in the above-ground biomass and of the metal uptake (i.e., the potential removal of the soil metals in g ha−1 and per year). Flax demonstrated a shorter growth cycle, with shorter and thicker plants and higher yields when sown in spring compared to winter sowing. Plant growth and productivity were not evidently influenced by additional nitrogen fertilization during plant growth. The cadmium bioaccumulation factor was 1.06, indicating that flax accumulates this metal. For Ni, Cu, Pb, and Zn, the corresponding values were 0.0, 0.04, 0.004, and 0.02, suggesting that this crop excludes these metals. The order of the higher uptake in plant tissues was as follows: Zn > Pb > Cd > Cu > Ni. In conclusion, flax demonstrated tolerance to heavy metals in the soil, effectively supporting soil restoration through cultivation. Additionally, flax showed potential as a cadmium accumulator while excluding nickel, copper, lead, and zinc.

Broccoli serves as a functional food because it can accumulate selenium (Se), well-known bioactive amino-acid-derived secondary metabolites, and polyphenols. The chemical and physical properties of Se are very similar to those of sulfur (S), and competition between sulfate and selenate for uptake and assimilation has been demonstrated. Towards an efficient agronomic fortification of broccoli florets, the working questions were whether we could overcome this competition by exogenously applying the S-containing amino acids cysteine (Cys) or/and methionine (Met), or/and the precursors of Glucosinolate (GSL) types along with Se application. Broccoli plants were cultivated in a greenhouse and at the beginning of floret growth, we exogenously applied sodium selenate in the concentration gradient of 0, 0.2, 1.5, and 3.0 mM to study the impact of increased Se concentration on the organic S (Sorg) content of the floret. The Se concentration of 0.2 mM (Se0.2) was coupled with the application of Cys, Met, their combination, or a mixture of phenylalanine, tryptophane, and Met. The application took place through fertigation or foliar application (FA) by adding isodecyl alcohol ethoxylate (IAE) or a silicon ethoxylate (SiE) surfactant. Fresh biomass, dry mass, and Se accumulation in florets were evaluated, along with their contents of Sorg, chlorophylls (Chl), carotenoids (Car), glucoraphanin (GlRa), glucobrassicin (GlBra), glucoiberin (GlIb), and polyphenols (PPs), for the biofortification efficiency of the three application modes. From the studied selenium concentration gradient, the foliar application of 0.2 mM Se using silicon ethoxylate (SiE) as a surfactant provided the lowest commercially acceptable Se content in florets (239 μg or 0.3 μmol g−1 DM); it reduced Sorg (−45%), GlIb (−31%), and GlBr (−27%); and it increased Car (21%) and GlRa (27%). Coupled with amino acids, 0.2 mM Se provided commercially acceptable Se contents per floret only via foliar application. From the studied combinations, that of Met,Se0.2/FA,IAE provided the lowest Se content per floret (183 μg or 0.2 μmol g−1 DM) and increased Sorg (35%), Car (45%), and total Chl (27%), with no effect on PPs or GSLs. Cys,Met,Se0.2/FA,IAE and amino acid mix,Se0.2/FA,IAE increased Sorg content, too, by 36% and 16%, respectively. Thus, the foliar application with the IAE surfactant was able to increase Sorg, and methionine was the amino acid in common in these treatments, with varying positive effects on carotenoids and chlorophylls. Only the Cys,Met,Se0.2 combination presented positive effects on GSLs, especially GlRa, but it reduced the fresh mass of the floret. The foliar application with SiE as a surfactant failed to positively affect the organic S content. However, in all studied combinations of Se 0.2 mM with amino acids, the Se content per floret was commercially acceptable, the yield was not affected, the content of GSLs was increased (especially that of GlRa and GlIb), and PPs were not affected. The content of GlBr decreased except for the treatment with methionine (Met,Se0.2/FA,SiE) where GlBr remained unaffected. Hence, the combination of Se with the used amino acids and surfactants can provide enhanced biofortification efficiency in broccoli by providing florets as functional foods with enhanced functional properties.

Sulfate is taken up from the soil solution by the root system; and inside the plant, it is assimilated to hydrogen sulfide, which in turn is converted to cysteine. Sulfate is also taken up by the leaves, when foliage is sprayed with solutions containing sulfate fertilizers. Moreover, several other sulfur (S)-containing compounds are provided through foliar application, including the S metabolites hydrogen sulfide, glutathione, cysteine, methionine, S-methylmethionine, and lipoic acid. However, S compounds that are not metabolites, such as thiourea and lignosulfonates, along with dimethyl sulfoxide and S-containing adjuvants, are provided by foliar application—these are the S-containing agrochemicals. In this review, we elaborate on the fate of these compounds after spraying foliage and on the rationale and the efficiency of such foliar applications. The foliar application of S-compounds in various combinations is an emerging area of agricultural usefulness. In the agricultural practice, the S-containing compounds are not applied alone in spray solutions and the need for proper combinations is of prime importance.

Pollen grains of 19 Fritillaria (Liliaceae) taxa and 2 hybrids from Greece were investigated by scanning electron microscopy. The majority of the taxa are studied for the first time and 13 of them are Greek endemic plants. All studied Fritillaria taxa had symmetrical, heteropolar and monosulcate grains, with prolate or perprolate shape. Eight types of exine sculpturing were observed: rugulate-reticulate, rugulate-perforate, psilate-perforate, perforate-reticulate, reticulate, reticulate-heterobrochate and psilate-reticulate. The sulcus always extends from distal to proximal and its apex is either round or sharp. The sulcus membrane is rugulate-granulate, psilate-granulate, gemmate or, as in most cases, verrucate. Our study provides new data on the pollen morphology of Fritillaria, ensures its inter- and intra-specific heterogeneity, and suggests that pollen morphological characters may contribute to the classification of Fritillaria taxa at species level.

The aim of this work was to study maize root phenotype under sulfur deficiency stress towards revealing potential correlations between the altered phenotypic traits and the corresponding dry mass, sulfur, and iron allocation within plants at the whole-plant level. The dynamics of root morphological and anatomical traits were monitored. These traits were then correlated with plant foliage traits along with dry mass and sulfur and iron allocation dynamics in the shoot versus root. Plants grown under sulfate deprivation did not seem to invest in new root axes. Crown roots presented anatomical differences in all parameters studied; e.g., more and larger xylem vessels in order to maximize water and nutrient transport in the xylem sap. In the root system of S-deficient plants, a reduced concentration of sulfur was observed, whilst organic sulfur predominated over sulfates. A reduction in total iron concentration was monitored, and differences in its subcellular localization were observed. As expected, S-deprivation negatively affected the total sulfur concentration in the aerial plant part, as well as greatly impacted iron allocation in the foliage. Phenotypic adaptation to sulfur deprivation in maize presented alterations mainly in the root anatomy; towards competent handling of the initial sulfur and the induced iron deficiencies.

Sulfur (S) is an essential macronutrient for plants, being necessary for their growth and metabolism and exhibiting diverse roles throughout their life cycles. Inside the plant body, S is present either in one of its inorganic forms or incorporated in an organic compound. Moreover, organic S compounds may contain S in its reduced or oxidized form. Among others, S plays roles in maintaining the homeostasis of essential micronutrients, e.g., iron (Fe), copper (Cu), zinc (Zn), and manganese (Mn). One of the most well-known connections is homeostasis between S and Fe, mainly in terms of the role of S in uptake, transportation, and distribution of Fe, as well as the functional interactions of S with Fe in the Fe-S clusters. This review reports the available information describing the connections between the homeostasis of S and Fe, Cu, Zn, and Mn in plants. The roles of S- or sulfur-derived organic ligands in metal uptake and translocation within the plant are highlighted. Moreover, the roles of these micronutrients in S homeostasis are also discussed.

In this chapter root anatomical traits and trait states, and nutrient acquisition mechanisms, along with the environmental issues affecting nutrient acquisition are summarized. Then, the whole range of adaptations of root anatomical traits, and its impact on nutrient acquisition are discussed. Combinations of anatomical traits lead to suggestions of root ideotypes potentially capable of supporting agricultural productivity under different edaphic constraints. Spatiotemporal aerenchyma formation in the various root types of maize under nitrate, phosphate or sulfate deprivation is discussed in a case study.

Plant growth promoting rhizobacteria (PGPR) can be functional microbial fertilizers and/or biological control agents, contributing to an eco-spirit and safe solution for chemical replacement. Therefore, we have isolated rhizospheric arylsulfatase (ARS)-producing bacteria, belonging to Pseudomonas and Bacillus genus, from durum wheat crop grown on calcareous soil. These isolates harbouring plant growth promoting (PGP) traits were further evaluated in vitro for additional PGP traits, including indole compounds production and biocontrol activity against phytopathogens, limiting the group of multi-trait strains to eight. The selected bacterial strains were further evaluated for PGP attributes associated with biofilm formation, compatibility, salt tolerance ability and effect on plant growth. In vitro studies demonstrated that the multi-trait isolates, Bacillus (1.SG.7, 5.SG.3) and Pseudomonas (2.SG.20, 2.C.19) strains, enhanced the lateral roots abundance and shoots biomass, mitigated salinity stress, suggesting the utility of beneficial ARS-producing bacteria as potential microbial fertilizers. Furthermore, in vitro studies demonstrated that compatible combinations of multi-trait isolates, Bacillus sp. 1.SG.7 in a mixture coupled with 5.SG.3, and 2.C.19 with 5.SG.3 belonging to Bacillus and Pseudomonas, respectively, may enhance plant growth as compared to single inoculants.

In vase life studies, cut flower fresh weight is often recorded, but mass distribution is not. Here, we addressed the variation in mass distribution among the different cut flower organs, and assessed its role in water relations. In the first part of the study, excised leaves, flower, and stem were exposed to desiccation. Water loss (per fresh mass) of both flower and stem was low, relatively constant over time and comparable between the three studied cultivars. Instead, water loss (per fresh mass) of leaves was initially much higher, and decreased upon desiccation due to stomatal closure. Leaves had the greatest contribution to cut flower water loss, while this contribution was different among the tested cultivars. Similar findings were obtained following evaluation of the contribution of leaves, stem, and flower to cut flower transpirational water loss under conditions where water supply was not limiting. A strong correlation between the leaf weight loss in the desiccation experiment and the length of vase life was found. Low evaporative demand during vase life evaluation increased vase life, and alleviated vase life differences between cultivars. Instead, high evaporative demand during evaluation shortened vase life, and increased the noted differences in vase life between cultivars. In the second part of the study, fresh weight partitioning was assessed within and among cut rose cultivars. Among eight cultivars, same weight flowering stems may have over 11% difference in leaf weight. In conclusion, cultivar differences in transpirational water loss between cut flowers of the same weight may be attributed to variations in both stomatal characteristics and mass partitioning to the leaves.

The compatibility of macronets with soil and their hydrophilic character as well increase proportionally to the number of ionic groups that are introduced into their structure. A variety of examples of starch-polyacrylamide conditioner application in soil systems is reported while blends of starch-grafted polyacrylonitrile or polyacrylamide with unmodified starch or polyvinyl alcoholare reported. The ion-exchange properties are associated with an increase of the hydrophilic character and result in elevated swelling degrees of the polymer in polar media, when ionic groups are introduced to cross-linked macronets to a certain degree, usually more than 25% of the available units. The recent trends and perspective of cross-linked polymeric soil conditioners (PSC) are particularly connected with postpolymerization processes. So cross-linked PSC, prepared via postpolymerization reactions are based on various modifications of linear macromolecules and grafted or block copolymers with multifunctional compounds as cross-linking agents.

Employing supplementary light (SL) with increased energy efficiency would reduce cultivation costs of greenhouse grown crops. Prior to implementation, however, the plant response to the resultant dynamic cog-efficient light regime ought to be addressed. This response was examined in two Passiflora genotypes by evaluating growth, chlorophyll fluorescence of (expanding and fully-expanded) leaves, as well as stomatal anatomy (density, index, size and pore dimensions) and gas exchange response to evaporative demand. The control plants received fixed day length SL, whereas other plants received a cost-efficient light regime with fluctuating periods of SL based on forecasted solar irradiance and electricity price. The dynamic cost-efficient light pattern neither impeded flower development nor delayed the flowering time in either genotype. Dynamic light promoted (22 %) biomass accumulation in one genotype, which also exhibited increased (34,8 %) assimilation rate over a large evaporative demand range (7-18 mb). Stomatal anatomical traits and the quantum efficiency of open photosystem II centers (F-v/F-m) were not affected by the light regime. Although both genotypes exhibited increased stomatal conductance (25-44 %) under the dynamic cost-efficient light regime, the stomatal response to evaporative demand was not attenuated. These results indicate that SL can be dynamically scheduled without compromising either the external quality traits or the control of water loss in Passiflora pot plants.

High relative air humidity (RH >= 85%) is frequent in controlled environments, and not uncommon in nature. In this review, we examine the high RH effects on plants with a special focus on stomatal characters. All aspects of stomatal physiology are attenuated by elevated RH during leaf expansion (long-term) in C-3 species. These include impaired opening and closing response, as well as weak diel oscillations. Consequently, the high RH-grown plants are not only vulnerable to biotic and abiotic stress, but also undergo a deregulation between CO2 uptake and water loss. Stomatal behavior of a single leaf is determined by the local microclimate during expansion, and may be different than the remaining leaves of the same plant. No effect of high RH is apparent in C-4 and CAM species, while the same is expected for species with hydropassive stomatal closure. Formation of bigger stomata with larger pores is a universal response to high RH during leaf expansion, whereas the effect on stomatal density appears to be species- and leaf side-specific. Compelling evidence suggests that ABA mediates the high RH-induced stomatal malfunction, as well as the stomatal size increase. Although high RH stimulates leaf ethylene evolution, it remains elusive whether or not this contributes to stomatal malfunction. Most species lose stomatal function following mid-term (4-7 d) exposure to high RH following leaf expansion. Consequently, the regulatory role of ambient humidity on stomatal functionality is not limited to the period of leaf expansion, but holds throughout the leaf life span.

Sulfur is an essential macronutrient for growth of higher plants. The entry of the sulfate anion into the plant, its importation into the plastids for assimilation, its long-distance transport through the vasculature, and its storage in the vacuoles require specific sulfate transporter proteins. In this study, mycorrhizal and non-mycorrhizal maize plants were grown for 60 days in an S-deprived substrate, whilst iron was provided to the plants in the sparingly soluble form of FePO4. On day 60, sulfate was provided to the plants. The gene expression patterns of a number of sulfate transporters as well as sulfate assimilation enzymes were studied in leaves and roots of maize plants, both before as well as after sulfate supply. Prolonged sulfur deprivation resulted in a more or less uniform response of the genes' expressions in the roots of non-mycorrhizal and mycorrhizal plants. This was not the case neither in the roots and leaves after the supply of sulfur, nor in the leaves of the plants during the S-deprived period of time. It is concluded that mycorrhizal symbiosis modified plant demands for reduced sulfur, regulating accordingly the uptake, distribution, and assimilation of the sulfate anion.

As an essential nutrient required for plant growth and development, sulfur (S) deficiency in productive systems limits yield and quality. This special issue hosts a collection of original research articles, mainly based on contributions from the 11th International Plant Sulfur Workshop held on 16–20 September 2018 in Conegliano, Italy, focusing on the following topics: (1) The germinative and post-germinative behaviour of Brassica napus seeds when severe S limitation is applied to the parent plants; (2) the independence of S deficiency from the mRNA degradation initiation enzyme PARN in Arabidopsis; (3) the glucosinolate distribution in the aerial parts of sel1-10, a disruption mutant of the sulfate transporter SULTR1;2, in mature Arabidopsis thaliana plants; (4) the accumulation of S-methylcysteine as its γ-glutamyl dipeptide in Phaseolus vulgaris; and (5) the role of ferric iron chelation-strategy components in the leaves and roots of maize, have provided new insights into the effect of S availability on plant functionality. Moreover, the role of S deficiency in root system functionality has been highlighted, focusing on (6) the contribution of root hair development to sulfate uptake in Arabidopsis, and (7) the modulation of lateral root development by the CLE-CLAVATA1 signaling pathway under S deficiency. The role of S in plants grown under drought conditions has been investigated in more detail focusing (8) on the relationship between S-induced stomata closure and the canonical ABA signal transduction machinery. Furthermore, (9) the assessment of S deficiency under field conditions by single measurements of sulfur, chloride, and phosphorus in mature leaves, (10) the effect of fertilizers enriched with elemental S on durum wheat yield, and (11,12) the impact of elemental S on the rhizospheric bacteria of durum wheat contributed to enhance the scientific knowledge on S nutrition under field conditions.

Iron (Fe) is an essential element for plant growth and productivity, and human and animal diets rely on Fe from plant sources. Despite the large number of studies on plants’ Fe deficiency responses, considerably less is known about the morphological and anatomical alterations that root systems of plants undergo, especially in the graminaceous plants following a chelation strategy to take up Fe3+ from the rhizosphere. A stress symptom observed in Fe-deprived maize plants is an ectopic lateral root branching occurring at the terminal 5 cm of the root. In order to understand this response, one-week-old maize seedlings were placed in containers with either full nutrient solution, or nutrient solution lacking an Fe source. Control and Fe-deprived plants were grown for another 14 days, and the trait of ectopic lateral root branching was observed both on roots that emerged before the onset of Fe deprivation, as well as on roots that emerged after the onset of the deprivation. Ongoing in silico analysis of a quantitative trait locus known to be related to this trait of maize grown under limited Fe, revealed several genes coding for known and unknown proteins, as well as long intergenic non-coding RNAs.

Increasing the light level in protected cultivation of ornamental crops via supplementary lighting is critical to enhance both production and external quality especially during the periods of low light availability. Despite wide applications the effects of light intensities were not previously addressed on water loss pathways. In this study rose plants were cultivated at 100, 200 or 400 μmol/(m2.s) photosynthetic photon flux density (PPFD). The stomatal responsiveness to desiccation, stomatal anatomical features and cuticular transpiration were determined. Plant biomass as well as photosynthesis response to light and CO2 were also assessed. Increasing growth PPFD led to a considerable increase in plant biomass (85 and 57% for 100 to 200 and 200 to 400 μmol/(m2.s) respectively). Photosynthesis was marginally affected by increasing growth PPFD from 100 to 200 μmol/(m2.s) while a further rise to 400 μmol/(m2.s) considerably increased photosynthetic rate at high light intensities. Higher PPFD during cultivation generally led to larger stomata with bigger pores. A PPFD increase from 100 to 200 μmol/(m2.s) had a small negative effect on stomatal closing ability whereas a further rise to 400 μmol/(m2.s) had a substantial stimulatory effect. Cultivation at a PPFD higher than 100 μmol/(m2.s) led to lower rates of cuticular transpiration. In conclusion, high growth PPFD (> 200 μmol/(m2.s)) enchanced both photosynthetic and stomatal anatomical traits. High light intensity (> 200 μmol/(m2.s)) also led to a better control of water loss due to more responsive stomata and decreased cuticular permeability.

The genus Fritillaria is represented in Greece by 31 taxa, more than a half of which are endemic to the country. This is the first report studying the seed morphology of this genus in Greece, in an attempt to prove its taxonomic importance. Seeds from 59 Greek populations, representing 25 taxa have been studied concerning 11 morphological parameters. All examined taxa have numerous seeds per capsule that are flat and characterised by the presence of a peripheral wing. Their shape is ovate to widely ovate-triangular, with the exception of F. epirotica which is more hemispherical. The smallest seeds of all studied taxa belong to F. montana. The morphometric data, along with the multivariate analysis (PCA) and paired t-tests, can lead to interesting conclusions concerning the taxonomic relationships among several taxa. For example, taxa currently considered as synonyms, like F. sporadum within F. ehrhartii and F. theophrastii within F. pontica are found statistically different concerning seed morphology. On the other hand, taxonomically well distinct taxa, such as F. ionica subsp. thessala, F. graeca, and F. messanensis subsp. gracilis, share similar seed morphology. Finally, the two—very similar—subspecies of Fritillaria obliqua share the same seed features, rising again questions upon their taxonomic distinctiveness.