Search Results (153)

Scaligeria napiformis (Willd. ex Spreng) Grande is an underutilized wild edible plant associated with the Cretan flora and diet, yet cultivation-oriented information on its response to nutrient management remains limited. This study compared two practical foliar nutrient management regimes, including a biostimulant-containing foliar product (INM-b) and a conventional foliar fertilization regime (CovF), together with an untreated control (Ctrl). Relative chlorophyll status, assessed by SPAD, maximum quantum efficiency of PSII photochemistry (Fv/Fm), CIE L*a*b* leaf colour parameters, fresh and dry biomass, and macro- and micronutrient concentrations in the edible aerial parts were determined. Foliar nutrient management significantly affected the SPAD-based relative chlorophyll status, leaf colour, edible biomass and selected mineral elements, whereas Fv/Fm was not significantly affected by treatment. CovF was associated with the highest SPAD values, darker, greener and less yellow leaves, and the highest N, Zn and Fe concentrations. Both INM-b and CovF increased fresh and dry biomass relative to the Ctrl and increased the P, K and Mn concentrations, while Ca, Mg and B were not significantly affected. Because INM-b and CovF differed in nutrient composition, formulation and nutrient supply, the present design does not isolate the specific effect of the biostimulant-containing component. Therefore, these findings should be interpreted as preliminary responses of S. napiformis to the tested foliar management strategies under pot cultivation, requiring future validation through isonutrient-, factorial- and field-based experiments. Full article

Understanding phenotypic variation in traits associated with drought and heat tolerance is essential for developing climate-resilient spring wheat cultivars under increasingly variable environmental conditions. To evaluate phenotypic and physiological variation in water-use efficiency (WUE), carbon isotope discrimination (δ¹³C), and heat tolerance, 198 Canadian spring wheat cultivars representing diverse breeding backgrounds were assessed under controlled drought and high-temperature conditions. Traits measured included whole-plant water-use efficiency (WUE_WP), carbon isotope composition (δ¹³C), biomass accumulation, water use per plant, and chlorophyll fluorescence across six developmental stages. Whole-plant WUE ranged from 3.07 to 7.81 g L⁻¹, while δ¹³C values ranged from −24.06‰ to −29.33‰. Biomass accumulation and water use were strongly positively correlated (r = 0.94, p < 0.001), indicating that greater biomass production was associated with increased water consumption. In contrast, the relationship between WUE_WP and δ¹³C was weak (r = −0.09), suggesting that δ¹³C alone may not be a reliable proxy for WUE_WP under combined drought and heat stress conditions. Phenotypic diversity across the cultivar panel was relatively low to moderate (Shannon diversity index, H^′ = 1.88–2.62), indicating limited adaptive capacity within the evaluated germplasm. Principal component analysis explained 76.6% of the total variation and effectively differentiated cultivar responses to stress. Chlorophyll fluorescence, particularly the maximum quantum efficiency of PSII photochemistry (F_V/F_M), was highly sensitive to stress-induced reductions in photosynthetic performance. Measurements obtained during reproductive drought and heat stress stages showed stronger associations with biomass, water use, WUE_WP, and δ¹³C than measurements collected during non-stress periods, indicating that F_V/F_M can be a reliable physiological indicator for screening drought and heat tolerance. Overall, the results revealed detectable phenotypic variation but relatively modest diversity and generally weak to moderate trait associations, highlighting the potential value of incorporating diverse germplasm and integrated phenotyping approaches to improve climate resilience in Canadian spring wheat. Full article

Drought stress during early growth stages severely limits wheat productivity globally. Understanding varietal physiological responses to drought stress is critical for breeding climate-resilient cultivars. Two-week-old plants from two winter wheat (Triticum aestivum L.) cultivars—Katya (drought-tolerant) and Zora (drought-sensitive)—were subjected to drought for seven days, followed by rehydration. The experiments were conducted in pots in controlled conditions. The photosystem II (PSII) function was evaluated using chlorophyll a fluorescence (OJIP transients), thermoluminescence emissions and pigment content analysis. Under drought, Katya maintained functional PSII integrity with stable quantum efficiency and increased chlorophyll content, while Zora exhibited chlorophyll degradation. Fresh and dry weight declined in both genotypes but significantly only in Zora; recovery occurred after rehydration. Chlorophyll fluorescence revealed that varietal divergence was localized to the O–J phase of PSII photochemistry, indicating differences in reaction-center behavior confirmed by thermoluminescence. Katya demonstrated preserved PSII reaction-center density, balanced energy partitioning, homogeneous PSII populations, and superior recovery capacity. Conversely, Zora showed reaction-center depletion, elevated energy dissipation, impaired electron transport beyond Q_A, and persistent PSII heterogeneity even after rehydration. Drought tolerance in the studied genotypes was associated with the maintenance of PSII structural integrity, efficient photochemical function, and rapid recovery mechanisms. These physiological markers—particularly early PSII photochemistry kinetics and reaction-center stability—provide valuable selection criteria for breeding programs, targeting drought resilience under changing climate conditions. Full article

Weed interference and herbicide-induced phytotoxicity, particularly from HPPD inhibitors such as tembotrione, represent significant limitations to yield stability in grain sorghum. Developing strategies to enhance crop tolerance without compromising weed control is of high practical interest. This study tested the hypothesis that a commercial Ascophyllum nodosum-based biostimulant can mitigate tembotrione-induced oxidative stress and phytotoxicity in sorghum without compromising the weed-control activity of the herbicide. Sorghum plants at the V4 phenological stage (four fully expanded leaves) were subjected to five treatments: (1) untreated control; (2) biostimulant application alone; (3) tembotrione application alone; (4) simultaneous application of tembotrione and biostimulant; and (5) tembotrione followed by biostimulant application after six days of application (6 DAT). After 10 days of treatment, photosynthetic pigment synthesis, primary photochemistry, gas exchange, antioxidant metabolism, phytotoxicity levels, growth parameters, and yield indices were evaluated. The results support the hypothesis that A. nodosum-based biostimulants can act as effective mitigating agents. The biostimulant sustained carotenoid levels and preserved the stability of the photosynthetic apparatus (PSII), counteracting HPPD enzyme inhibition caused by the herbicide. Isolated biostimulant application upregulated net photosynthesis by 60%, while simultaneous co-application with tembotrione preserved membrane integrity and the leaf area index. Furthermore, the efficacy of the mitigation strategy was highly time-dependent, as simultaneous co-application proved superior to the delayed (6 DAT) intervention. From an agronomic perspective, the biostimulant reduced visual injury and restored the grain number per plant to control levels under simultaneous co-application, although the final yield of combined treatments did not differ statistically from either the untreated control or the treatment of tembotrione alone. This study shows that the integration of A. nodosum extracts into the chemical management of sensitive crops represents a viable biotechnological strategy to enhance herbicide selectivity and yield stability. Full article

The necrotrophic pathogen Sclerotinia sclerotiorum compromises the physiological and anatomical integrity of cotton, leading to substantial economic losses due to rapid tissue necrosis, stem blight, boll rot, and leaf wilting. In this context, the use of endophytic microorganisms emerges as a promising strategy for the biocontrol of white mold. This study tested the hypothesis that endophytic fungal strains isolated from the roots of Butia purpurascens, a palm tree endemic to the Cerrado biome, could mitigate disease symptoms in Gossypium hirsutum L. To evaluate this, cotton plants were subjected to biotic stress imposed by S. sclerotiorum to assess the effectiveness of seven fungal strains in attenuating disease. The impact of the pathogen was monitored through growth variables, gas exchange, leaf temperature, chlorophyll a fluorescence, antioxidant enzyme activity, proline and malondialdehyde (MDA) levels, and the incidence of rot in petioles, leaves, and flower buds. Overall, inoculation with endophytic fungi significantly alleviated the effects of the phytopathogen, promoting vegetative growth and optimizing physiological performance. Treated plants exhibited alleviated stress in primary photochemistry, reduced non-photochemical energy dissipation, and stable carbon fixation. Additionally, efficient modulation of the antioxidant system and preservation of anatomical structures were observed, minimizing the severe symptoms of white mold. Notably, the non-pathogenic strains BP10EF (Gibberella moniliformis), BP16EF (Penicillium purpurogenum), and BP33EF (Hamigera insecticola) acted as potent physiological modulators, yielding responses similar to those of healthy plants. These results highlight the biotechnological potential of these endophytic strains, which can be explored as both growth promoters and resistance inducers in cotton against white mold. Full article

The damage caused by herbivores is generally measured as the amount of leaf tissue consumed, without accounting for the fate of the leftover tissue. As a result, the plant defense mechanisms that promote resistance to herbivore feeding by photosynthetically acclimating the rest of the plant to the feeding spot leaf area have not been well exploited. Plant-insect interactions are now becoming better defined with the development of visualization methods that permit spatial whole-leaf assessment of photosynthetic efficiency after herbivore attack. The purpose of our study was to evaluate the spatial heterogeneity of photosystem II (PSII) function at the whole-leaf level before and after herbivory by the Colorado potato beetles. Twenty minutes after Colorado potato beetle (Leptinotarsa decemlineata) feeding, the maximum efficiency of PSII photochemistry (Fv/Fm) decreased significantly, suggesting photoinhibition due to reduced efficiency of the oxygen-evolving complex (OEC). The decreased quantum yield of PSII photochemistry (Φ_PSII) after feeding, at the neighboring area of the feeding spot and at the rest of the leaf area, was attributed to the reduced efficiency of the open PSII reaction centers (Fv′/Fm′), since there was no change in the fraction of open PSII reaction centers (qp). Nevertheless, plant defense elicitation was activated by the photoprotective mechanism of non-photochemical quenching (NPQ) that reduced the singlet oxygen (¹O₂) formation in potato plants in the neighboring area of the feeding spot and at the rest of the leaf area. In addition, the increased production of hydrogen peroxide (H₂O₂) triggered by this increase suggests that it acted as a signaling molecule in the biotic stress defense response. Full article

Drought is a major environmental threat to agriculture. This study examined the role of anthocyanins in plant drought tolerance by comparing two basil varieties differing in leaf anthocyanin content: green basil (Ocimum basilicum L. Italiano Classico) and purple basil (Ocimum basilicum L. Dark Opal). The impact of the PEG-induced drought stress was assessed by monitoring changes in chlorophyll a fluorescence parameters (JIP and PAM), leaf pigment content, anthocyanin and total phenolic levels, oxidative stress markers (malondialdehyde, hydrogen peroxide and membrane integrity), as well as radical-scavenging capacity (DPPH assay). Drought stress led to a modification on both the donor (Wk) and acceptor (Vj) sides of PSII, which influences Q_A reoxidation and amounts of the closed reaction centers (1-qP). These changes inhibited photosystem II photochemistry, the rate of the electron transport (ETR), and the rate of the photosynthesis (R_Fd) and decreased performance indices (PI_ABS, PItotal), as well as the photosystem I photochemistry. The drought-induced changes were associated with an increase in the dissipated energy per reaction center (DI₀/RC). The results show that photosynthetic functions in purple basil were less affected under drought stress compared to green basil. The reason for better tolerance of purple basil is associated with elevated anthocyanin levels, which correlate with enhanced antioxidant capacity, reduced hydrogen peroxide accumulation, lower membrane lipid peroxidation, improved relative water content and membrane stability. In addition, rapid cyclic electron flow around photosystem I and a higher carotenoid to chlorophyll ratio contribute to drought tolerance in purple basil. After re-watering, purple basil recovers its photosynthetic function almost completely, unlike green basil, which shows further suppression. The increase in the anthocyanin content and radical-scavenging capacity, as well as the smaller oxidative damage under drought stress, are the main reasons for the better recovery in purple basil. Overall, the findings highlight that higher anthocyanin accumulation in purple basil confers greater drought tolerance and recovery capacity by stabilizing photosynthetic processes and reducing oxidative stress. Full article

Sosnovsky’s hogweed (Heracleum sosnowskyi Manden.) is an invasive plant species widely distributed across Eastern Europe and Russia that poses a serious threat to human health due to its pronounced phototoxic properties. Contact with the plant sap followed by exposure to solar ultraviolet (UV) radiation frequently results in phytophotodermatitis, which is characterized by erythema, blistering, ulceration, and persistent hyperpigmentation. The development of these photochemical injuries—most notably furanocoumarins—act as potent photosensitizers and induce cellular and DNA damage upon UV activation. This review provides an integrated overview of the geographical spread and invasiveness of H. sosnowskyi, the chemical composition of its biologically active metabolites, and the molecular mechanisms underlying hogweed-induced skin injury. Particular emphasis is placed on the photochemical transformations of furanocoumarins, including psoralens and their photooxidation products, such as 1,2-dioxetanes, which generate reactive oxygen species and DNA crosslinks. In addition, the review examines other compounds derived from hogweed biomass—including furan derivatives, aromatic compounds, fatty acids, sterols, and their oxidative products—that may contribute to phototoxic and cytotoxic effects. Clinical manifestations of hogweed-induced burns, their classification, symptomatology, and current therapeutic approaches are critically discussed, highlighting the absence of standardized treatment guidelines. Rather than serving as a purely clinical or botanical survey, this review frames Sosnovsky’s hogweed injury as a solar-light-activated photochemical hazard, tracing the sequence from environmental sunlight exposure through molecular photochemistry to biological tissue damage. By integrating chemical, biological, and dermatological perspectives, the review aims to clarify injury mechanisms and support the development of more effective preventive and mitigation strategies under real-world exposure conditions. Full article

We used chlorophyll fluorescence techniques to investigate seasonal variations in photosystem II (PSII) quantum yield in five-year-old saplings of the sclerophyllous Peumus boldus Molina (evergreen) and Colliguaja odorifera Molina (semideciduous) planted in a semiarid site with a Mediterranean-type climate. Chlorophyll fluorescence rise kinetics (OJIP) were monitored monthly for one year (September 2024 to September 2025). With this information, we estimated the relative deviation of the performance index (PI_ABS) of each species from the average PI_ABS in each season (denoted as ∆PI_ABS). P. boldus was associated with destruction of PSII reaction centers and incapacity for electron transport, i.e., higher values of parameters ABS/RC (effective antenna size of an active reaction center) and F₀ (minimal fluorescence), whereas C. odorifera was associated with higher photosynthetic performance i.e., higher values of PI_ABS, PI_TOT (total performance index), F_V/F₀ (ratio between variable and minimal fluorescence), and F_V/F_M (maximum quantum yield of primary PSII photochemistry). P_IABS exhibited a 52 and 38% reduction (i.e., −∆PI_ABS) during spring and winter in P. boldus, but an increase (i.e., +∆PI_ABS) of 52 and 37% in the same seasons for C. odorifera. P. boldus was considerably more depressed during the winter–spring season than the summer months. This suggests that PSII function in P. boldus is more sensitive to low temperatures in winter and spring than the lack of water and high temperatures during summer. Full article

Salinity has been recognized as one of the major environmental stresses that restrict the growth and quality of celery (Apium graveolens L.). Therefore, this study investigates the impact of different NaCl concentrations on celery growth and photosynthetic characteristics, as well as the potential regulatory role of exogenous trehalose application in mitigating the stress-induced effects. The results indicated that an increase in NaCl concentration from 50 to 200 mM markedly inhibited the growth of celery plants compared to that under control conditions. The application of different concentrations of trehalose mitigated the inhibitory effects of salt stress (100 mM NaCl) on celery growth and photosynthesis. Among the different trehalose treatments, T3 (10 mM trehalose) exhibited the most significant effects, increasing the aboveground biomass, belowground biomass, plant height, chlorophyll a, chlorophyll b, total chlorophyll, and net photosynthetic rate compared to that of salt stress alone, respectively. Furthermore, trehalose treatments enhanced the various fluorescence parameters, including the maximum efficiency of PSII photochemistry (Fv/Fm), coefficient of photochemical quenching (qP), fluorescence intensity, and photosynthetic performance index (PIabs) under salt stress. Meanwhile, trehalose reduced intercellular carbon dioxide concentration, excess excitation energy (1-qP)/NPQ, heat dissipation per unit area (DIo/CSm), and energy dissipated per reaction center (DIo/RC). Additionally, the results of principal component analysis (PCA) and membership function comprehensive evaluation indicate that an appropriate concentration of trehalose positively alleviates the salnitiy-induced effects in celery. Overall, the T3 demonstrated the most promising effects on mitigating the effects of salt stress by decreasing the excess excitation energy of PSII in celery leaves through the heat dissipation pathway. This reduction lowers the excitation pressure on the reaction centers, enhances the activity of PSII reaction centers per unit cross-section, and improves photosynthesis activity, thereby improving the growth of celery plants under salt stress. Full article

Global warming is increasingly constraining plant productivity by altering the photosynthetic energy balance and leaf thermoregulation. Under high light and elevated temperatures, absorption of energy in excess (AEE) by photosystem II disrupts photosynthetic electron transport, oxygen evolution, and CO₂ assimilation, often accompanied by reduced foliar transpiration. These conditions promote photoinhibition, as reflected by a decrease in maximal photosynthetic efficiency (Fv/Fm), an increase in non-photochemical quenching (NPQ), and photooxidative stress associated with enhanced reactive oxygen species (ROS) production. In addition to environmental heat stress, AEE influences foliar temperature through internal energy partitioning, including regulated dissipation of AEE as heat and changes in transpirational cooling. The relative contributions of NPQ, photochemistry, and transpiration to leaf temperature regulation are strongly context dependent and vary with light intensity, temperature changes, and water availability. Under global warming, rising background temperatures and increased vapor pressure deficit may constrain transpirational cooling and alter the balance between non-photochemical and photochemical energy dissipation and usage, respectively. In this review, we synthesize current knowledge on AEE handling, photoinhibition, NPQ and other quenching processes, and on transpiration cooling, and discuss a conceptual framework in which sustained imbalance among these processes under global warming conditions could amplify foliar heat stress and increase the risk of cellular damage. Rather than proposing new physiological mechanisms, this work integrates existing evidence across molecular, leaf, and ecosystem scales to highlight potential feedbacks relevant to plant performance under future climate prediction scenarios. Full article

This study aimed to evaluate the physiological responses and yield of Tahiti lime (Citrus latifolia) cultivated at high density under three soil moisture tension (SMT) levels: low (L = −0.010 MPa), medium (M = −0.035 MPa), and high (H = −0.085 MPa). Measurements included water status, sap flow, photochemical activity, gas exchange, and fruit yield during the dry and early rainy seasons. The leaf water potential (Ψ_L) and relative water content (RWC) were higher in the L and M treatments than in H, with an overall improvement at the onset of the rainy season. From the dry to the rainy season, sap flow decreased by 25.3, 16.0, and 1.9 L day⁻¹ in L, M, and H plants, respectively. Plants with higher soil water availability (L and M) maintained better water status during the dry season, which favored photochemistry and gas exchange, reflected in a greater shoot growth and fruit yield (54.5 and 53.4 kg plant⁻¹, respectively). In contrast, H SMT significantly reduced water relations and photosynthetic activity, leading to yield loss. Short-term rainfall (six days) was insufficient to restore physiological performance. Maintaining SMT around −0.035 MPa during the dry season optimizes yield while reducing water use. Full article

Food security and human health are directly related to the condition of agricultural soils. Soil contamination by heavy metals is a global environmental problem. Lead (Pb) is a toxic and non-biodegradable element posing a significant risk to ecosystems and human health. 24-Epibrassinolide (EBR) has multiple benefits in plant metabolism, including maximizing gas exchange. In plants, exogenous application of dopamine (DOP) confers tolerance to abiotic stresses, minimizing interferences on growth. This study aimed to investigate whether the exogenous application of EBR and DOP, administered independently or jointly, can contribute to mitigating the oxidative stress and impacts on photosystem II in Pb-stressed tomato, evaluating parameters related to nutritional status, photosystem II activity, gas exchange, antioxidant enzymes, and biomass. Better results were observed with the isolated EBR application, improving the photosynthetic efficiency, as evidenced by the increases in chlorophyll contents, effective quantum yield of PSII photochemistry, photochemical quenching coefficient, and electron transport rate, resulting in a higher net photosynthesis rate. Parallelly, treatment using both plant growth regulators (DOP and EBR) promoted significant increases of 14%, 18%, 13%, and 35% in the activities of superoxide dismutase, catalase, ascorbate peroxidase, and peroxidase, contributing to the reduction in oxidative stress in photosystem II of Pb-stressed plants. Therefore, this research proves that the exogenous application of DOP and EBR, alone or in combination, attenuates the toxic effects generated by Pb in tomato plants. Full article

Drought stress is a major abiotic factor limiting plant growth and productivity. This study investigates the role of oligomerization of the light-harvesting complex of photosystem II (LHCII) in modulating plant responses to drought stress. Using pea plants (Pisum sativum L.): Borec (wild type) and its mutants Costata 2/133 and Coeruleovireus 2/16, with different degrees of LHCII oligomerization, we examined the impact of water deficit on the functions of the photosynthetic apparatus. This study demonstrated that plants with a higher degree of LHCII oligomerization (wild type and Coeruleovireus 2/16) have enhanced drought tolerance, expressed by reduced lipid peroxidation and membrane damage, protection of the photosynthetic pigment content, which corresponds with better photosynthetic performance. Data revealed only minor drought-induced inhibition of photosystem II (PSII) photochemistry (Fv/Fm, Φ_PSII), electron transport rate (ETR), and rate of photosynthesis (R_Fd)), along with sustained performance indices (PI_ABS and PItotal) in plants with higher LHCII oligomerization compared to those with lower levels (Costata 2/133). Additionally, the current study indicates that under drought stress and low actinic light, the interaction with plastoquinone and controlled dissipation of excess energy are promoted in thylakoid membranes with increased LHCII oligomerization. In contrast, drought-stressed plants with lower oligomerization (Costata 2/133) showed a significant increase in non-regulated energy losses under high actinic light. These results highlight the protective function of LHCII oligomerization in preserving photosynthetic integrity and functioning under drought stress and suggest that it could be a promising target for enhancing crop resilience in a changing climate. Full article

Cadmium (Cd) is a non-essential element that induces reactive oxygen species (ROS) production and damages the photosynthetic apparatus. Dopamine (DOP) is a neurotransmitter that plays a role in metabolism as an antioxidant. This research aimed to investigate whether exogenous DOP mitigates Cd-induced oxidative stress in soybean by assessing antioxidant metabolism, stress indicators, nutritional status, pigments, chlorophyll fluorescence, gas exchange, and biomass. The experiment was randomized with four treatments: two with Cd concentrations (0 and 500 µM Cd, described as—Cd and +Cd, respectively) and two DOP levels (0 and 100 µM DOP described as—DOP and +DOP, respectively). DOP mitigated Cd-induced damage by enhancing the antioxidant system and protecting the photosynthetic apparatus. This neurotransmitter positively modulated the enzymes superoxide dismutase (38%), catalase (27%), ascorbate peroxidase (23%), and peroxidase (31%), alleviating Cd-induced oxidative stress. In addition, DOP promoted increases in the effective quantum yield of PSII photochemistry (26%), photochemical quenching coefficient (18%), and electron transport rate (26%). Simultaneously, the neurotransmitter stimulated increases in the net photosynthetic rate (29%), stomatal conductance (35%), water use efficiency (38%), and instantaneous carboxylation efficiency (39%). Our results indicate that DOP exogenous increases tolerance to Cd-induced stress in soybean plants. Full article