Sara Ibáñez-Asensio

Essential oil-bearing plants are valued for their aromatic qualities and medicinal value. An example of such a plant is sage (Salvia officinalis L.), one of the most important aromatic herbal plants. Rich in essential oil (EO), sage herb is used in pharmaceutical and cosmetic production and as a spice. This study was conducted to determine the effect of arbuscular mycorrhizal fungi (AMF) on the morphological characteristics, yield, and EO production of sage under different irrigated conditions: 95 ± 5, 75 ± 5, 50 ± 5, and 25 ± 5% field capacity (FC). Maximum herb dry biomass yield and leaf dry biomass yield were obtained at the 95, 75% FC irrigation level, and the highest leaf EO (1.361%) was at 75% FC. The high yield of herb and leaf dry biomass, as well as the highest EO in herb and leaves, was observed with AMF. A group of monoterpenes and sesquiterpenes dominated the EO. The main compounds were 1,8-cineole, α-thujone, β-thujone, camphor, E-caryophyllene, and viridiflorol. The chemical composition of EO has changed under irrigation. Under severe stress (25% FC) and moderate soil moisture (50% FC), the proportion of monoterpene hydrocarbons and oxidized sesquiterpenes was higher than at 75% and 95% FC. The proportion of camphor, α-thujone, and β-thujone was higher with AMF only under severe water stress. With increasing soil moisture, the proportion of α-thujone and β-thujone in EO decreased. A positive correlation was found between EO content and the number of leaves per plant. Our results indicate the prospects for practical application of AMF in combination with the irrigation of sage plants.

Cardoon leaves are of great pharmaceutical importance due to their high content of polyphenol compounds. Polyphenolic compounds have attracted much interest due to their health-promoting effects. The content of these compounds in C. cardunculus depends on several factors, such as genotype, crop management, plant tissues, harvest time, and storage time. In this study, the effects of nitrogen (N) fertilisation (rates and forms) on the biomass yield and polyphenol profile of the leaves were determined. Increasing the amount of N up to 180 kg-ha⁻¹ in fertilisation did not significantly increase the air-dried biomass yield of the leaves. On the contrary, it led to lower concentrations of total phenolic compounds (TP), total flavonoids (TF), caffeic acid, cynarin, and luteolin. Improvements in performance were achieved when 120 kg-ha⁻¹ N rate was applied and increases in TP, TF content, and radical scavenging activity were observed. The applied N forms (NO₃, NH₄ or urea) had different effects on the concentrations of individual compounds and leaf air-dried biomass. Higher concentrations of cynarin, luteolin, and luteolin-7-O-glucoside were found when the N forms NH₄ and urea were applied; higher caffeic acid content was found when urea was applied. The application of NO₃ and urea in fertilisation reduced the level of luteolin-7-O-rutinoside, while the application of NO₃ and NH₄ reduced the amount of caffeic acid. The obtained results provide a better understanding of the effects of N rates and forms on cardoon leaves over two growing seasons.

Soil salinity is one of the major causes of losses in agricultural production, which is accentuated by global warming. A sustainable strategy to mitigate the effects of the increasing soil salinisation is the use of biostimulants. In this study, the effect of a plant-based biostimulant was tested on tomato plants exposed to different salinity levels in loamy and sandy soils. Salinity in the soils reached a maximum value of 14.35 dS m⁻¹. The treatments included a control (tap water) and a dose of 0.4 mL L⁻¹ of the commercial biostimulant BALOX^®, containing polyphenols and glycine betaine. After 60 days of treatment, several growth and biochemical parameters were evaluated in the plants, and different responses were found depending on the type of soil texture. Salt stress inhibited plant growth, mainly affecting the roots of plants not treated with the biostimulant, in both soil texture types. It also caused a reduction of total chlorophyll and carotenoid levels by 44% and 38%, respectively, under severe salinity conditions. High salinity induced a significant increase in ionic, osmotic and oxidative stress in plants, as indicated by the accumulation of toxic Na⁺ and Cl⁻ ions, higher proline and MDA levels, and increased antioxidant enzyme activities. However, the application of BALOX^® stimulated plant growth and root system development in all experimental conditions. The areas of roots and leaves and the stem length and diameter showed higher mean values in biostimulant-treated plants on both soil types, with more pronounced differences with the controls in sandy soils. The total fresh weight showed maximum increases of 54% and 93% on loamy and sandy soils, respectively. In addition, BALOX^® significantly improved the active transport of nutrients such as K⁺ and Ca²⁺, and the concentration of photosynthetic pigments by up to 64% over control values; it also allowed greater protection against salt stress as shown by a significant reduction of proline levels, by up to 36%, and MDA by 51% under strongly saline conditions. The application of BALOX^® generally decreased the level of stress in the tomato plants, promoting plant growth and enhancing their biochemical responses, even on strongly salinised soils.

Global warming is linked to progressive soil salinisation, which reduces crop yields, especially in irrigated farmland on arid and semiarid regions. Therefore, it is necessary to apply sustainable and effective solutions that contribute to enhanced crop salt tolerance. In the present study, we tested the effects of a commercial biostimulant (BALOX^®) containing glycine betaine (GB) and polyphenols on the activation of salinity defense mechanisms in tomato. The evaluation of different biometric parameters and the quantification of biochemical markers related to particular stress responses (osmolytes, cations, anions, oxidative stress indicators, and antioxidant enzymes and compounds) was carried out at two phenological stages (vegetative growth and the beginning of reproductive development) and under different salinity conditions (saline and non-saline soil, and irrigation water), using two formulations (different GB concentrations) and two doses of the biostimulant. Once the experiments were completed, the statistical analysis revealed that both formulations and doses of the biostimulant produced very similar effects. The application of BALOX^® improved plant growth and photosynthesis and assisted osmotic adjustment in root and leaf cells. The biostimulant effects are mediated by the control of ion transport, reducing the uptake of toxic Na⁺ and Cl⁻ ions and favoring the accumulation of beneficial K⁺ and Ca²⁺ cations, and a significant increase in leaf sugar and GB contents. BALOX^® significantly reduced salt-induced oxidative stress and its harmful effects, as evidenced by a decrease in the concentration of oxidative stress biomarkers, such as malondialdehyde and oxygen peroxide, which was accompanied by the reduction of proline and antioxidant compound contents and the specific activity of antioxidant enzymes with respect to the non-treated plants.

Climate change accentuates abiotic stress conditions putting at risk several commercial cultivars particularly vulnerable to salinity in the early stages of development, which makes adopting new technologies in tune with the environment necessary to mitigate its impact. In this study, we tested the possible effects of a commercial biostimulant (BALOX^®) on enhancing salt stress tolerance in salt-treated tomato plants, analysing plant growth and several stress biochemical markers: photosynthetic pigments, ion contents in roots and leaves, leaf concentrations of different osmolytes, oxidative stress markers, non-enzymatic antioxidants, and the specific activities of major antioxidant enzymes. The experimental design consisted of three soil salinity levels (non-saline, saline, and very saline), two biostimulant doses (0.4 mL and 0.8 mL of the BALOX^® stock per litre of irrigation water), and the non-treated control (without biostimulant), evaluated at 30 and 60 days of treatment. The biostimulant favoured plant growth, especially at the root level and in saline soils. In addition, it helped reduce Na⁺ and Cl⁻ uptake by the roots and seemed to stimulate, to some extent, K⁺ and Ca²⁺ transport to the aerial part of the plant. The BALOX^® application significantly reduced the level of stress affecting the plants in saline soils, as shown by the decrease in the contents of proline and oxidative stress biomarkers and the activity of salt-induced antioxidant enzymes. Some of the biostimulant effects were also observed under low salinity conditions; therefore, in addition to enhancing salt stress responses, BALOX^® appears to stimulate the growth of tomato plants through a general improvement of photosynthesis and primary metabolism.

Artichoke herb is of great pharmaceutical importance, mainly due to the high content of phenolic compounds. This paper presents the effect of late nitrate (N) fertilization with mineral and organic N on the yield of air-dried herb, the total content of polyphenolic acids (TCQA), the polyphenolic profile as well as on the antioxidant activity (AA). These parameters were measured in organic (ORG) and conventional (CON) cropping systems. The principal outcomes revealed that the highest TCQA content was determined in the herbal extracts of ORG management treatments with late N fertilization of 20 kg ha⁻¹. This result explained the highest AA content of the extract in the ABTS+ (2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)), FRAP (ferric-reducing antioxidant power), and DPPH (2,2-diphenyl-1-picrylhydrazyl) assays. Late N fertilization increased the content of cynarin and ferulic acid in both systems. In addition, chlorogenic acid increased between 37% and 45% in the CON cropping systems depending on the fertilizer dose. In the same treatment, luteolin increased 39% compared to the control. Lastly, in the ORG management system, caffeic acid and apigenin content increased 10% and 30%, respectively. Both treatments showed high collinearity values, where ORG systems were related to ferulic acid and cynarin, and CON systems were associated with chlorogenic acid and AA potential (ABTS, DPPH, FRAP). To sum up, ORG cropping systems can obtain an acceptable yield size with a high-quality content of bioactive compounds, allowing a better understanding of the effect of N fertilization in ORG and CON cropping systems.