Theodora Matsi

Tulipa scardica (Balkan endemic) was last recorded in Greece in 1896, possibly attributed to longstanding taxonomic ambiguity, as it has frequently been considered as conspecific with T. gesneriana or T. undulatifolia. In the present study we aimed to investigate the historical Greek locality of T. scardica and to reassess its taxonomic status in comparison with the closely related T. undulatifolia (also native to Greece and member of T. scardica complex). Targeted field surveys were conducted to verify the presence of T. scardica in Greece. The newly identified tulip population was subjected to an integrated analytic approach, including qualitative and quantitative morphological assessment, seed micromorphology, DNA barcoding, karyological investigation, and habitat/soil properties analyses. These datasets were comparatively evaluated against four reference populations of T. undulatifolia. Molecular data did not provide consistent species-level resolution, whereas morphological and karyological evidence statistically supported their distinction. Mitotic metaphase chromosomes of T. scardica were documented herein for the first time, while first-time scanning electron microscopy (SEM) analysis revealed the presence of different types of stomatal complexes in seed coats of both taxa. In addition, soil parameters differed between the examined taxa, and those of the rediscovered population were consistent with habitat preferences of T. scardica. Although both taxa exhibited considerable variability, the combined evidence derived from the present study strongly supported the rediscovery of T. scardica in Greece after approximately 130 years, unless proven otherwise in a wider context across its Balkan range.

Melon ( Cucumis melo L . ) is a globally significant crop, yet its productivity is increasingly threatened by rising soil salinity in many cultivation areas. In this context, plant growth‐promoting rhizobacteria (PGPR) have emerged as a promising strategy to enhance plant growth and improve tolerance to salinity stress. This study investigated the effect of inoculating melon seedlings with a previously characterized strain AXSa06 (identified as Pseudomonas oryzihabitans ) under salt stress (250 mM NaCl), focusing on plant growth, photosynthesis, antioxidant responses, metabolomic profiles, nutrient balance, abscisic acid (ABA) levels, and expression of ABA signaling pathway genes. Inoculation improved the growth and photosynthetic performance of melon plants under salt stress, while reducing Na ⁺ accumulation and facilitating better nutrient homeostasis. The elevated levels of malondialdehyde (MDA) and catalase (CAT), along with the increased ABA content upon inoculation, pointed to a priming effect that prepared plants to manage oxidative stress, as evidenced by the reduced antioxidant activity upon stress. Expression of CmPYL9 and several CmPP2AC isoforms was upregulated only in inoculated stressed plants, suggesting improved ABA sensitivity and a fine‐tuned transcriptional control of signaling. AXSa06‐inoculated stressed plants also displayed notable metabolic reprogramming, primarily affecting carbohydrate metabolism, following shifts in TCA cycle metabolites already evident under control conditions. Taken together, these findings suggest that AXSa06 could serve as a promising biostimulant agent improving melon tolerance to salt stress by modulating physiological and biochemical responses. This study offers valuable insights into PGPR‐driven stress priming and its role in developing strategies for sustainable crop production under saline conditions.

Knowledge concerning the use of solid residues from the distillation of medicinal and aromatic plants (MAP) as amendments-fertilizers for acid soils, instead of their combustion or disposal to the environment, is too limited. The aim of the study was a preliminary evaluation of the use of solid residues from the distillation of selected medicinal and aromatic plants as amendments-fertilizers for acid soils. Specifically, in the perspective of further and extensive investigation, the fertilization capacity of solid residues from the distillation of selected MAP was initially realized and the optimal range of application rates of the residues to acid soils was initially determined. From that point of view, the present study was a preliminary study and lasted for six months. Solid residues from the distillation of hemp ( Cannabis sativa L.), helichrysum ( Helichrysum italicum (Roth) G. Don), lavender ( Lavandula angustifolia Mill.), oregano ( Origanum vulgare L.), rosemary ( Rosmarinus officinalis L.) and sage ( Salvia officinalis L.) were collected from industries of essential oils of northern Greece. Then the residues were added to a strongly to moderately acid soil at 0 (control), 1, 2, 4 and 8% rates (treatments), in three replications and the soil treatments were analyzed for chemical properties and fertility indices. pH significantly increased compared with control upon the addition of all residues at the 2% rate and above. Although pH remained acid in all cases, it increased more than one unit in soils treated with 4% and 8% flower-leaf residues from hemp distillation, making soil’s reaction slightly acidic. Similar results were obtained for electrical conductivity (EC) and the carbon/nitrogen (C/N) ratio. It is worth noting that EC increased six-ten times upon the 8% application of flower-leaf residues, whereas the C/N ratio increased considerably with the 8% addition of lavender and helichrysum residues. Regarding soil available macronutrients, nitrate-nitrogen (NO ₃ -N), phosphorus (P) and potassium (K) significantly increased from adequate to high levels compared with control. From the soil available micronutrients, only boron (B), zinc (Zn) and manganese (Mn) consistently affected by the application of residues and significantly increased. It is worth noting the multiple increases of B and Zn in soils treated with 8% residues compared with control, which were somewhat concerning. In almost all treatments, soil available B, Cu and Zn ranged at sufficiency levels, whereas Fe and Mn ranged at high levels. The solid residues from the distillation of the studied MAP, especially the flower-leaf residues, could be used as amendments-fertilizers for acid soils, at application rates between 2 and 4%. Rates lower than 2% are not expected to significantly affect soil properties, whereas rates higher than 4% should be avoided, because of risks of soil salinization, N immobilization and B, Zn and probable Mn phytotoxicities. Graphical Abstract

The current study focuses on a preliminary evaluation of the use of solid residues produced from the distillation of selected medicinal and aromatic plants (MAP) as fertilizers for alkaline soils. Specifically, the residues of hemp (Cannabis sativa L.), helichrysum (Helichrysum Italicum (Roth) G. Don), lavender (Lavandula angustifolia Mill.), oregano (Origanum vulgare L.), rosemary (Rosmarinus officinalis L.) and sage (Salvia officinalis L.) were added in an alkaline and calcareous soil at the rates of 0 (control), 1, 2, 4 and 8%, in three replications (treatments), and the treated soils were analyzed. The results showed that upon application of the residues, soil electrical conductivity (EC), organic C, total N and the C/N ratio significantly increased, especially at the 4 and 8% rates. The same was found for soil available P, K, B, Cu and Mn. The effects of the residues on soil pH, cation exchange capacity (CEC) and available Zn and Fe were rather inconclusive, whereas soil available N significantly decreased, which was somewhat unexpected. From the different application rates tested, it seems that all residues could improve soil fertility (except N?) when they were applied to soil at rates of 2% and above, without exceeding the 8% rate. The reasons for the latter statement are soil EC and available Mn: the doubling of EC upon application of the residues and the excessive increase in soil available Mn in treatments with 8% residues raise concerns of soil salinization and Mn phytotoxicity risks, respectively. This work provides the first step towards the potential agronomic use of solid residues from MAP distillation in alkaline soils. However, for the establishment of such a perspective, further research is needed in respect to the effect of residues on plant growth and soil properties, by means of at least pot experiments. Based on the results of the current study, the undesirable effect of residues on soil available N should be investigated in depth, since N is the most important essential element for plant growth, and possible risks of micronutrient phytotoxicities should also be studied. In addition, application rates between 2 and 4% should be studied extensively in order to recommend optimum application rates of residues to producers.

Origanum dictamnus L. (Lamiaceae), a local endemic plant of Crete (Greece), creates polysaccharide-containing subcuticular compartments presenting biological activity against phytopathogenic fungi, and, among others, significantly affects the fungal cell wall polysaccharides. This field study introduces a fertilization scheme for O. dictamnus, which was developed and refined to optimize the yield as well as critical herbal quality aspects. Five fertilization schemes were investigated, based on a polysaccharide-based Integrated Nutrient Management (INM), a mixture of conventional inorganic fertilizers (ChF) and two biostimulants (not algae) via foliar and soil application. Plant growth, together with leaf chlorophyll fluorescence and color (SPAD meter, DA meter, Chroma Meter) were determined. The leaf content of chlorophyll, three critical antioxidant compounds (carotenoids, flavonoids, phenols) and nutrients were also assessed. Considering all three antioxidants together, the enhanced efficiency, non-toxic, water-soluble, polysaccharide-based INM by foliar application was the most stimulatory scheme, playing an important role in plant growth and development. The present field study provides, for the first time, baseline fertilization data improving key herbal quality features in O. dictamnus and unravels the attainment of high antioxidant properties. The latter may be exploited in favor of its further utilization as a raw material for tea preparation, medicinal purposes, natural food flavoring and/or food preservative.

Due to the combined climate and biodiversity crisis, the sustainable utilization of phytogenetic resources stands as a one-way alternative, while nutrient management strategies are gaining an increasing role in agriculture. Building on previous studies regarding the Endangered local endemic of Crete (Greece) Carlina diae (Asteraceae), with medicinal and ornamental value, this investigation focused on its pilot cultivation and fertilization (foliar or soil application). Foliar application comprised inorganic fertilization (conventional) or integrated nutrient management (INM). Soil application consisted of conventional inorganic fertilizers, biostimulants, or INM with biostimulants. Above-ground biomass content of nutrients, leaf chlorophyll fluorescence, and color parameters (SPAD meter, DA meter, Chroma Meter) were estimated. The leaf chlorophyll content, three key antioxidant compounds, and nutrient titers were also determined. The fertilization scheme did not influence plant growth and visually perceived quality (leaf color and shape). Notably, foliar INM fertilization increased biomass partitioning to inflorescences (harvestable organs for either medicinal or ornamental purposes) and decreased tissue water content (facilitating processing). Considering all three antioxidants together, INM with biostimulant appeared the optimum scheme, being associated with the highest (carotenoids, phenolics) or the second highest (flavonoid) content. In C. diae, therefore, INM fertilization was optimal for upgrading yield (foliar) and herbal quality in terms of antioxidant profile (INM with biostimulant), which might be embraced as an eco-friendly approach for high-quality yields.

Herein, we applied DNA barcoding for the genetic characterization of Sideritis syriaca subsp. syriaca (Lamiaceae; threatened local Cretan endemic plant) using seven molecular markers of cpDNA. Five fertilization schemes were evaluated comparatively in a pilot cultivation in Crete. Conventional inorganic fertilizers (ChFs), integrated nutrient management (INM) fertilizers, and two biostimulants were utilized (foliar and soil application). Plant growth, leaf chlorophyll fluorescence, and color were assessed and leaf content of chlorophyll, key antioxidants (carotenoids, flavonoids, phenols), and nutrients were evaluated. Fertilization schemes induced distinct differences in leaf shape, altering quality characteristics. INM-foliar and ChF-soil application promoted yield, without affecting tissue water content or biomass partitioning to inflorescences. ChF-foliar application was the most stimulatory treatment when the primary target was enhanced antioxidant contents while INM-biostimulant was the least effective one. However, when the primary target is yield, INM, especially by foliar application, and ChF, by soil application, ought to be employed. New DNA sequence datasets for the plastid regions of petB/petD, rpoC1, psbK-psbI, and atpF/atpH were deposited in the GenBank for S. syriaca subsp. syriaca while the molecular markers rbcL, trnL/trnF, and psbA/trnH were compared to those of another 15 Sideritis species retrieved from the GenBank, constructing a phylogenetic tree to show their genetic relatedness.

Due to combined climate and biodiversity crisis, the sustainable utilization of phytogenetic resources stands as one-way alternative while nutrient management strategies gain an increasing role in agriculture. Building on previous studies regarding the Endangered local endemic of Crete (Greece) Carlina diae (Asteraceae) with medicinal and ornamental value, this investigation focused on its pilot cultivation and fertilization (foliar or root application). Foliar application included chemical fertilizer (conventional) or integrated nutrient management (INM). Root application consisted of chemical fertilizer, biostimulant, or INM with biostimulant. Above-ground biomass content of nutrients, together with leaf chlorophyll fluorescence and colour parameters (SPAD meter, DA meter, Chroma Meter) were determined. The leaf content of chlorophyll, three key antioxidant compounds and minerals’ titers were also assessed. The fertilization scheme did not influence plant growth and visually perceived quality (leaf color and shape). Notably, foliar INM fertilization increased biomass partitioning to inflorescences (harvestable organ for either medicinal or ornamental purposes), and decreased tissue water content (facilitating processing). Considering all three antioxidants together, INM with biostimulant appeared the optimum scheme, being associated with the highest (carotenoids, phenolics) or the second highest (flavonoid) content. In C. diae, therefore, INM fertilization was optimal for upgrading yield (foliar) and herbal quality in terms of antioxidant profile (INM with biostimulant), which might be embraced as an eco-friendly approach for high quality yields.

Origanum dictamnus L. (Lamiaceae), a local endemic plant of Crete (Greece), creates polysaccharide-containing subcuticular compartments presenting biological activity against phytopathogenic fungi, and, among others, significantly affecting the fungal cell wall polysaccharides. This field study introduces a fertilization scheme for O. dictamnus, which was developed and refined to optimize yield as well as critical herbal quality aspects. Five fertilization schemes were investigated, based on a polysaccharide-based Integrated Nutrient Management (INM), a mixture of chemical fertilizers and two biostimulants (not algae) via foliar and soil application. Plant growth, together with leaf chlorophyll fluorescence and colour (SPAD meter, DA meter, Chroma Meter) were determined. The leaf content of chlorophyll, three critical antioxidant compounds (carotenoids, flavonoids, phenols) and minerals were also assessed. Considering all three antioxidants together, the enhanced efficiency, non-toxic, water-soluble, polysaccharide-based INM by foliar application was the most stimulatory scheme, playing an important role in plant growth and development. The present field study provides for the first time baseline fertilization data improving key herbal quality features in O. dictamnus and unravels the attainment of high antioxidant properties. The latter may be exploited in favor of its further utilization as raw material for tea preparation, medicinal purposes, natural food flavoring and/or food preservative.