Search Results (270)

Cucumbers (Cucumis sativus L.) are highly sensitive to cold, but grafting onto cold-tolerant rootstocks can enhance their low-temperature resilience. This study investigates the physiological and molecular mechanisms by which exogenous vitamin C (Vc) mitigates cold stress in grafted cucumber seedlings. Using cucumber ‘Chiyu 505’ as the scion and pumpkin ‘Chuangfan No.1’ as the rootstock, seedlings were grafted using the whip grafting method. In the third true leaf expansion stage, seedlings were foliar sprayed with Vc at concentrations of 50, 100, 150, and 200 mg L⁻¹. Three days after initial spraying, seedlings were subjected to cold stress (8 °C) for 3 days, with continued spraying. After that, morphological and physiological parameters were assessed. Results showed that 150 mg L⁻¹ Vc treatment was most impactive, significantly reducing the cold damage index while increasing the root-to-shoot ratio, root vitality, chlorophyll content, and activities of antioxidant enzymes (SOD, POD, CAT). Moreover, this treatment enhanced levels of soluble sugars, soluble proteins, and proline compared to control. However, 200 mg L⁻¹ treatment elevated malondialdehyde (MDA) content, indicating potential oxidative stress. For transcriptomic analysis, leaves from the 150 mg L⁻¹ Vc and CK treatments were sampled at 0, 1, 2, and 3 days of cold stress. Differential gene expression revealed that genes associated with photosynthesis (LHCA1), stress signal transduction (MYC2-1, MYC2-2, WRKY22, WRKY2), and antioxidant defense (SOD-1, SOD-2) were initially up-regulated and subsequently down-regulated, as validated by qRT-PCR. Overall, we found that the application of 150 mg L⁻¹ Vc enhanced cold tolerance in grafted cucumber seedlings by modulating gene expression networks related to photosynthesis, stress response, and the antioxidant defense system. This study provides a way for developing Vc biostimulants to enhance cold tolerance in grafted cucumbers, improving sustainable cultivation in low-temperature regions. Full article

Sesame (Sesamum indicum L.) is widely cultivated for its valuable medicinal, aromatic, and oil-rich seeds. However, drought stress remains one of the most significant abiotic factors influencing its development, physiological function, and overall output. This study investigates the potential of foliar applications of silicon (Si), Sargassum muticum (Yendo) Fensholt extracts (SWE), and their combination to enhance drought tolerance and mitigate stress-induced damage in sesame. Plants were grown under well-watered conditions (80% field capacity, FC) versus 40% FC (drought conditions) and were treated with foliar applications of 1 mM Si, 10% SWE, or both. The results showed that the majority of the tested parameters were significantly (p < 0.05) lowered by drought stress. However, the combined application of Si and SWE significantly (p < 0.05) enhanced plant performance under drought stress, leading to improved growth, biomass accumulation, water status, and physiological traits. Gas exchange, photosynthetic pigment content, and photosystem activity (PSI and PSII) all increased significantly when SWE were given alone; PSII was more significantly affected. In contrast, Si alone had a more pronounced impact on PSI activity. These findings suggest that Si and SWE, applied individually or in combination, can effectively alleviate drought stress’s negative impact on sesame, supporting their use as promising biostimulants for enhancing drought tolerance. Full article

Old vineyards in production in the Pampa biome have high levels of metals, such as copper (Cu), zinc (Zn), and manganese (Mn). The high metal contents in the soil can damage the growth and development of the cover plant species that cohabit the vineyards. However, it is possible to define the critical toxicity level (CTL) of metals in soil and tissue in order to monitor and define possible strategies for reducing metal inputs and selecting more tolerant species. This study aimed to define the CTL of Cu, Zn, and Mn in the soil and plant tissue of plants present between the rows of vineyards with different cultivation histories in the Pampa biome in South America. For this purpose, soil and plant tissue samples were collected in a native field area (NF), without agricultural cultivation and in two vineyards, vineyard 1 (V1) and vineyard 2 (V2), both with a history of fungicide application. To define the CTL, the foliar concentrations and soil contents of Cu, Zn, and Mn were correlated with the dry mass production of the shoot. The CTLs for Cu, Zn, and Mn in the soil were set at 15, 3.0, and 35 mg kg⁻¹, respectively. In the tissue, CTLs for Cu, Zn, and Mn were estimated at 75, 77, and 380 mg kg⁻¹, respectively. The contents of Cu, Mn, and Zn in the soil of the vineyards are above the CTL. The concentrations of the metals in the tissue varied, with samples above the CTL for Cu and Zn in the vineyards. The values of Cu, Zn, and Mn in NF are below the CTL in soil and tissue. The high contents of Cu, Zn, and Mn in the soil and tissue limited the dry mass production of the plants between the rows of vineyards. Full article

This study evaluated the effects of reduced glutathione (GSH) application on the production and quality of sour passion fruit irrigated with brackish water in the semi-arid region of Paraíba, Brazil. The experiment was conducted in drainage lysimeters under greenhouse conditions at the Center of Technology and Natural Resources of the Federal University of Campina Grande (UFCG). Treatments combined five levels of electrical conductivity of brackish irrigation water (Bw: 0.4, 1.2, 2.0, 2.8, and 3.6 dS m⁻¹) and four GSH concentrations (0, 40, 80, and 120 mg L⁻¹), arranged in a randomized block design with three replicates. Salinity levels above 0.4 dS m⁻¹ negatively affected fruit production and post-harvest quality of ‘BRS GA1’ sour passion fruit. Foliar application of 120 mg L⁻¹ GSH increased fruit yield, while 74 mg L⁻¹ GSH mitigated salt stress effects on production and pulp chemical quality. The ‘BRS GA1’ cultivar was highly sensitive to salinity, showing a 26.9% yield reduction per unit increase in Bw electrical conductivity above 0.4 dS m⁻¹. The results suggest that GSH can alleviate salt stress damage, improving crop productivity and fruit quality under semi-arid conditions. Full article

Araucaria araucana is one of the longest-living Chilean trees. Recently, Araucaria Leaf Damage disease, which causes damage to branches and crowns, was detected. Sinophloeus porteri, a bark beetle affecting A. araucana, could be associated with foliar damage. However, little is known about their ecological and chemical interactions. This study examined the olfactory response of S. porteri to volatiles emitted from A. araucana. Branches and weevils were collected from a national park, and volatiles were trapped from both healthy and unhealthy branches. Thirty terpenes were identified, some of which were reported for the first time in A. araucana. Healthy branches emitted large amounts of myrcene (>360 ng g⁻¹ day⁻¹), and unhealthy branches showed high hibaene emanations (>140 ng g⁻¹ day⁻¹). Olfactory assays verified that S. porteri was attracted to the volatile blends of branches, regardless of the health condition of the branches, but preferred the blend of unhealthy branches. Moreover, myrcene was repellent to these weevils, and hibaene acted as an attractant, suggesting that A. araucana might use myrcene for defense against S. porteri, and hibaene could stimulate host selection by beetles. Full article

Silicon dioxide (SiO₂) foliar application offers a promising strategy for enhancing lettuce (Lactuca sativa L.) resilience under temperature extremes, salinity, and drought stress. This study investigated the effects of SiO₂ treatment on three lettuce cultivars exposed to varying temperature, salinity, and drought conditions in a controlled growth chamber environment. Silicon treatment (3.66 mM) significantly enhanced plant biomass under suboptimal (15 °C), optimal (20 °C), and salinity stress conditions. Notably, the SiO₂ effect was most positive under severe salinity stress (100 mM NaCl), where its application increased plant weight together with chlorophyll and anthocyanin content. When increasing SiO₂ concentrations from 0 to 29.30 mM were tested, optimal results to alleviate severe salinity stress were consistently observed at 3.66 mM, with peak performance in fresh weight, plant diameter, chlorophyll, and anthocyanin content. Higher SiO₂ concentrations progressively diminished these beneficial effects, with 29.30 mM treatment leading to reduced growth and increased leaf chlorosis. Comprehensive mineral composition analysis revealed complex interactions between silicon treatment and elemental profiles at 100 mM salinity stress. At 3.66 mM SiO₂, plants accumulated the highest levels of both K (20,406 mg/kg dry weight, DW) and Na (16,185 mg/kg DW) while maintaining the highest K/Na ratio (1.26). This suggests that Si enhances cellular ion compartmentalization rather than exclusion mechanisms, allowing plants to manage higher total ion content better while minimizing cytoplasmic damage. Drought stress conditions unexpectedly revealed negative impacts from 3.66 mM SiO₂ application, with decreased plant fresh weight at moderate (50% soil water content, SWC) and severe (30% SWC) water limitations, though results were statistically significant only under severe drought stress. The study highlights silicon’s potential as a stress mitigation agent, particularly under salinity stress, while emphasizing the need for concentration-specific and stress-specific approaches. These findings suggest that foliar SiO₂ application could be a valuable tool for enhancing lettuce crop productivity under both optimal and challenging environmental conditions, with future research warranting field validation and full market maturity assessments. Full article

Reclaimed water provides a sustainable and economical alternative for landscape irrigation, but its elevated salinity can negatively impact sensitive plant species. This study evaluated the salinity tolerance of two widely used ornamental grasses, Cymbopogon citratus (lemon grass) and Pennisetum alopecuroides (fountain grass), under three electrical conductivity (EC) levels: 1.2 (control), 5.0, and 10.0 dS·m⁻¹. Visual assessments over 62 days showed that both species maintained an acceptable appearance under saline conditions. C. citratus exhibited no foliar damage, with visual scores above 4.6 even at 10.0 dS·m⁻¹, whereas P. alopecuroides showed slight leaf injury but retained a score of 3.9 or higher. Growth parameters, such as plant height, leaf area, and shoot dry weight, decreased significantly in C. citratus with increasing salinity, particularly at 10.0 dS·m⁻¹, where reductions reached up to 51.1%. In contrast, P. alopecuroides maintained stable growth indices under salt stress, although leaf area and tiller number were notably affected at high EC levels. Both species accumulated substantial amounts of sodium (Na⁺) and chloride (Cl⁻); C. citratus showed more pronounced ion accumulation than P. alopecuroides. These findings suggest that both grasses are suitable for landscaping in saline environments, although they employ different physiological strategies to cope with salt stress. Full article

Cadmium (Cd) is a highly hazardous heavy metal that has an extensive impact throughout the world. 2,4-Epibrassinolide (BR) is an endogenous hormone that can enhance plant tolerance to various abiotic stresses. Herein, Vigna angularis cultivar “Zhen Zhuhong” was grown hydroponically and treated with 0, 1, and 2 mg·L⁻¹ cadmium chloride (CdCl₂) at the V1 stage, and foliar sprayed with or without 1 μM BR solution to analyze the effects of BR treatment on the physiology of Vigna angularis seedling leaves under Cd stress. BR treatment significantly alleviated the growth inhibition induced by Cd stress, which was associated with an increase in the plant height (11.15–17.83%), leaf area (35.59–56.72%), leaf dry weight (45.57–50.65%), and above-ground dry weight (50.86–55.17%). In addition, BR treatment induced significant reductions in Cd accumulation across different tissues of V. angularis, with decreases of 20.38–35.93% in leaves, 21.24–32.74% in stems, and 15.38–16.00% in petioles. Compared with the Cd treatment, BR treatment significantly enhanced the activities of peroxidase (5.02–13.22%), ascorbate peroxidase (27.13–70.28%), catalase (20.46–32.30%), and superoxide dismutase (16.54–21.81%), and increased the ascorbic acid content (27.55–45.52%), which contributed to a reduction in the accumulation of reactive oxygen species, cellular membrane damage, and cytoplasmic exosmosis. RNA-seq and real-time quantitative reverse transcription PCR analyses revealed that the BR treatment under Cd stress significantly upregulated the expression of genes involved in chlorophyll biosynthesis, transformation, and degradation, thereby enhancing the chlorophyll cycle. Furthermore, the BR treatment significantly increased the number of grana lamellae in the mesophyll cells, which enhanced the biosynthesis of chloroplasts. The increase in the chlorophyll content improved the capture of light energy, electron transport in photosynthesis, and the biosynthesis and metabolism of carbohydrates in the leaves of V. angularis under Cd stress. Full article

Drought stress negatively affects plant metabolism and growth, triggering complex defence mechanisms to limit damage. This study evaluated the effectiveness of a single foliar application of 1 mM L-proline (Pro) in winter wheat (Triticum aestivum L., cv. Bohemie) in two separate experiments differing in the time interval between application and drought—7 days (experiment 1) and 35 days (experiment 2). Net photosynthetic rate (A), transpiration rate (E), stomatal conductance (g_s), leaf water potential (Ψw), intrinsic water use efficiency (WUE_i), endogenous proline content (Pro), malondialdehyde content (MDA), and maximum quantum yield of photosystem II (F_v/F_m) were measured. In experiment 1, drought markedly reduced net photosynthetic rate, transpiration rate, stomatal conductance, and leaf water potential in both drought-stressed treatments, namely, without priming plants (S) and with Pro priming plants (SPro). Pro and MDA content increased under stress. Higher E and g_s in the SPro treatment indicated more effective stomatal regulation and a distinct water use strategy. Pro content was significantly lower in SPro compared to S, whereas differences in MDA levels between these treatments were not statistically significant. The second drought period (D2) led to more pronounced limitations in gas exchange in both S and SPro. Enhanced osmoregulation was reflected by lower Ψw (S < SPro) and higher Pro accumulation in S (S > SPro). The effect of exogenous Pro persisted in the form of reduced endogenous Pro synthesis and improved photosystem II protection. Rehydration of stressed plants restored all monitored physiological parameters, and Pro-treated plants exhibited a more efficient recovery of gas exchange. Experiment 2 demonstrated a long-lasting priming effect that improved the preparedness of plants for future drought events. In the SPro treatment, this stress memory supported more efficient osmoregulation, reduced lipid peroxidation, improved protection of photosystem II integrity, and a more effective restart of gas exchange following rehydration. Our findings highlight the potential of exogenous proline as a practical tool for enhancing crop resilience to climate-induced drought stress. Full article

The moth Helicoverpa armigera (Lepidoptera: Noctuidae), better known as the pod borer, poses significant threats to chickpea (Cicer arietinum L.) production. Therefore, effective and sustainable crop management strategies are required to mitigate the impact of this cosmopolitan pest. The present study aimed at investigating the potential of wood distillate (WD), a liquid byproduct of the pyrolysis of waste lignocellulosic biomass, to both reduce H. armigera pest incidence and to enhance crop yields in field-grown chickpea. The application of WD as a foliar spray effectively reduced the number of damaged pods by 35% during the plant´s reproductive stage compared with water-sprayed plants (~16 vs. 24 bored pods plant⁻¹, respectively) and increased the number of healthy pods (~16 vs. 10 pods plant⁻¹, respectively). Moreover, the lower pest incidence was accompanied by an improvement of both the seed yield and the quality at the plant´s full maturity stage. Specifically, WD-treated plants increased both the number and weight of seeds by ~80% compared to water-sprayed plants (~23 vs. 13 and 5.5 vs. 3 plant⁻¹, respectively) which further showed a remarkable improvement in their nutritional value, with the concentration of total polyphenols, flavonoids, starch, calcium, and magnesium increasing by 17%, 56%, 43%, 23%, and 15%, respectively. These results underscore the potential of WD to both improve chickpea performance and to reduce H. armigera damage to sustainably improve the productivity of this critical legume crop, aligning with the principles of the circular economy and offering an environmentally friendly alternative to synthetic pesticides and fertilizers in agriculture. Full article

This study aimed to evaluate the synergistic effects of zinc sulfate and Pseudomonas spp. in terms of mitigating drought stress in maize (Zea mays L.) by analyzing physiological, biochemical, and morphological responses under field conditions. A two-year (2018–2019) field experiment investigated two irrigation levels (optimal and moderate stress) and twelve treatment combinations of zinc sulfate application methods (without fertilizer, soil, foliar, and seed priming) with zinc-solubilizing bacteria (no bacteria, Pseudomonas fluorescens, and Pseudomonas aeruginosa). Drought stress significantly reduced chlorophyll content, increased oxidative damage, and impaired membrane stability, leading to a 42.4% increase in electrolyte leakage and a 10.9% reduction in leaf area index. However, the combined application of zinc sulfate and P. fluorescens, and P. aeruginosa mitigated these effects, with seed priming showing the most significant improvements. Specifically, seed priming with zinc sulfate and P. fluorescens increased catalase activity by 76% under non-stress conditions and 24% under drought stress. Principal component analysis revealed that treatments combining zinc sulfate and P. fluorescens, and P. aeruginosa were strongly associated with improved chlorophyll content, carotenoid content, and grain yield while also enhancing osmotic adjustment and antioxidant enzyme activity. These findings highlight the potential of the use of zinc sulfate and P. fluorescens as well as P. aeruginosa as sustainable strategies for enhancing maize drought tolerance, mainly through seed priming and soil application methods. Full article

Fire blight, caused by Erwinia amylovora, poses a significant threat to the sustainable development of the Korla Xiangli (Pyrus×sinkiangensis. Yu) industry. In this study, we used multiple experimental approaches to comprehensively evaluate the efficacy of three antagonistic bacterial strains—namely, Mg-7 (Leuconostoc mesenteroides), Rt-10 (Alcaligenes faecalis), and Rt-11 (Bacillus siamensis)—in controlling fire blight. In vitro plate inhibition assays revealed that Mg-7 exhibited the largest inhibition zone diameter, exceeding Rt-10 and Rt-11 in this respect, suggesting its strong antifungal potential. In therapeutic tests conducted on detached leaves, Mg-7 achieved the highest control efficiency, 60.39%, while Rt-10 demonstrated the greatest efficiency (76.96%) in protective tests. Conversely, in therapeutic trials focusing on detached branches, Mg-7 showed a control efficiency of 45.90%, whereas Rt-11 exhibited the highest efficiency, 86.27%, in protective trials. Furthermore, in vitro evaluations indicated that the Mg-7 treatment significantly reduced the lesion spread area. Enzymatic analyses revealed that, in the leaf protection assay, catalase activity (CAT) demonstrated significant increases of 65.56%, 85.46%, and 45.55% under the Mg-7, RT-10, and RT-11 treatments, respectively, when compared with the EA control group on day four. Correspondingly, in the branch protection assay, polyphenol oxidase (PPO) activity displayed marked elevations of 62.84%, 52.06%, and 82.69% under identical experimental conditions at the same time point. These treatments not only upregulated antioxidant enzyme activities but also significantly reduced malondialdehyde (MDA) content, effectively mitigating oxidative damage while enhancing foliar and branch resistance to fire blight infection. Field trials conducted in outdoor orchards confirmed that the Mg-7 bacterial suspension provided more effective and stable control against fire blight than Rt-10 and Rt-11. Overall, Mg-7 shows significant potential for use as a biocontrol agent for managing fire blight because of its high efficacy, stability, and ability to enhance plant defense responses. Full article

A laser-based selective wax ablation method using a 532 nm Nd:YAG laser was developed to improve the foliar uptake efficiency of agrochemicals in citrus leaves. In contrast to conventional applications that suffer major losses, our approach exposes up to 80% of the underlying epidermis (within the irradiated footprint) with no visible tissue damage, thereby substantially enhancing substance penetration. Efficacy was confirmed using two indicators: (1) A fluorescent glucose analog (2-NBDG) exhibited a radial expansion velocity reaching 0.0105 mm/min in treated areas, enabling rapid phloem transport across an 8 cm distance within just three minutes—an 11,280% improvement over untreated controls. (2) Laser-induced breakdown spectroscopy (LIBS) demonstrated a threefold increase in zinc (Zn) uptake (and over fivefold compared to untreated leaves) when using a Zn-based foliar fertilizer. To assess processing efficiency, we quantified the ablation footprint by combining single-pulse laser shots in a 1 cm-diameter region and found that 23.4% of the total area was fully exposed. This selective, non-invasive approach enables precise targeting, potentially reducing fertilizer and pesticide usage while improving crop health. Beyond citrus, it is readily adaptable to other crops, with integration into orchard or greenhouse spraying systems as a promising path for scale-up. Such versatility highlights the technique’s potential to optimize efficacy, cut input costs, and diminish environmental impact in modern precision agriculture. Full article

The success of double cropping in Vitis vinifera L. cultivated in temperate climates relies on bud forcing efficiency, which requires the prompt unlocking of apical dormant buds with sufficient fruitfulness. Chemical dormancy-breaking strategies need to be tested to enhance dormant bud forcing in summer pruning, as hydrogen cyanamide, the most used agent, could damage green organs. This study tested whether foliar applications of cytokinins and auxins could modulate dormancy release, potentially affecting bud forcing dynamics and shoot fruitfulness. The forcing treatments involved trimming primary shoots at the eighth node, removing lateral shoots, and retaining the main leaves and inflorescences. Five treatments were investigated: unforced control, control + 6-Benzyladenine application, forcing (FR), forcing + 6-Benzyladenine application (FBA), and forcing + Naphthaleneacetic acid application (FNAA). Phenological evolution, vegetative and productive parameters, and physiological characteristics have been assessed. Results showed that among the forcing treatments, FBA showed the highest forced/primary shoots ratio (106%), followed by FR (94%) and FNAA (21%). Primary yields were similar across treatments (2.74 kg), but total yield was highest in FBA (4.78 kg, including 2.02 kg from forced grapes), followed by FR (3.62 kg, with 1.09 kg forced). FNAA yielded no forced crop. During forced grapes maturation, photosynthesis rates were higher in forced leaves (11.1 μmol m⁻² s⁻¹, as FR and FBA average) than primary leaves (−32%). Forced grapes ripened 47 days later and achieved higher sugar content (21.7 °Brix) and titratable acidity (10.6 g/L) than primary grapes. The findings suggest cytokinins application enhances bud forcing, supporting the feasibility of double cropping, while auxins limited it. Full article

Ascorbic acid (ASC) is a molecule naturally synthesized in plant cells, protecting against abiotic stresses by reducing reactive oxygen species (ROS), which cause oxidative damage. Aluminum (Al) toxicity is the major limiting factor on crop productivity in acidic soils, increasing ROS within cells and impairing the growth and development of plants. Exogenous antioxidant applications are an effective strategy to promote tolerance to abiotic stress. The objective was to evaluate the effect of foliar ASC applications (0, 50, 100, 200, and 400 mg L⁻¹ ASC) and their interaction with Al toxicity (0, 400 µM Al) in Star, an Al-sensitive cultivar of highbush blueberry. Significant increases of 1.6-fold in growth were observed in roots and leaves under treatment with 200 mg L⁻¹ ASC. In the same treatment, increased pigments and antioxidant activity (~1.2- to 2.3-fold) were observed concomitant with reduced lipid peroxidation. Positive correlations between organic acid exudation, the ASC/DHA ratio, and calcium levels were observed, whereas a negative correlation between lipid peroxidation and dehydroascorbate (DHA) was observed. Foliar ASC application also increased the ASC/DHA ratio in leaves and enhanced 2.2-fold organic acid exudation in the 200 mg L⁻¹ ASC treatment. The results suggest that foliar ASC applications improved redox balance and underscore the potential of ASC as a practical solution to enhance resilience in Al-sensitive plants. Full article