Search Results (737)

Soil salinity inhibits biological nitrogen fixation (BNF) in legumes, compromising nitrogen nutrition and crop productivity. This study evaluated whether two halotolerant Mesorhizobium ciceri strains (S1, S2) can sustain BNF and alleviate moderate salt stress (100 mM NaCl) in three Tunisian chickpea (Cicer arietinum L.) cultivars (Amdoun, Béja 1, and Nour). Inoculated and non-inoculated plants were grown under controlled conditions. Salinity reduced shoot dry weight by 37.5–42% and severely impaired nodulation (≈60% reduction) in non-inoculated plants. Bacterial inoculation significantly increased germination rate, shoot and root biomass, and nodule number compared to non-inoculated salt-stressed controls. Improved nodulation corresponded to better nitrogen nutrition, reflected by higher leaf chlorophyll content (a proxy for nitrogen status). However, direct measurements of nitrogenase activity (e.g., acetylene reduction assay) are needed to confirm enhanced BNF. Inoculated seedlings also exhibited lower oxidative stress markers (hydrogen peroxide and malondialdehyde) and enhanced antioxidant enzyme activities (superoxide dismutase and glutathione peroxidase), indicating reduced reactive oxygen species damage. Cultivar-specific responses were observed: Amdoun responded best to S1, Béja 1 to S2 for biomass recovery, while Nour showed strong antioxidant induction but limited growth gain. We conclude that halotolerant M. ciceri strains improve chickpea performance under salt stress primarily by sustaining BNF and nodulation, thereby maintaining nitrogen nutrition. Strain–cultivar compatibility is critical for optimizing this bio-inoculant strategy in saline agroecosystems. Our findings identify the combination of cultivar Béja 1 with strain S2 as the most promising for biomass recovery under moderate salinity, providing a practical, strain–cultivar matching framework that can guide the development of effective bio-inoculants for chickpea production in salt-affected areas of Tunisia and similar Mediterranean regions. Full article

Salinity stress severely inhibits crop growth and reduces yield. Exogenous selenium (Se) enhances plant abiotic stress tolerance, but how different selenium forms exert their impacts and pathways in mitigating salinity remains ambiguous. Under salt stress, this work compared two Se forms, selenate [Se(VI)] and selenite [Se(IV)], regarding their impacts on development, photosynthetic performance, antioxidative system, osmotic regulators, Se buildup, and stress-related gene expression in Nicotiana tabacum L. Both Se species significantly promoted tobacco growth. (1) Under 150 mmol/L NaCl stress, biomass, net photosynthetic rate and antioxidant enzyme activities decreased significantly, while soluble sugar, free proline, Na⁺/K⁺, Na⁺/Ca²⁺, H₂O₂, MDA contents and NtROS2a, NtLEA5 expression increased significantly. (2) Exogenous Se increased biomass, photosynthetic parameters; antioxidant enzyme activities and NtNAC2, NtCDPK12, NtROS2a expression; elevated Se deposition in roots and leaves; and reduced oxidative damage, ion imbalance and NtLEA5 expression in salt-stressed tobacco, suggesting that Se may improve salt tolerance by regulating these physiological processes and stress-related gene expression. (3) Compared with Se(IV), Se(VI) significantly increased root length, chlorophyll content, stomatal conductance, K⁺ content, SOD/CAT activities, leaf and root Se accumulation as well as and NtNAC2, NtCDPK12 expression, while Se(IV) resulted in higher root diameter, free proline content, Na⁺/K⁺ ratio and NtROS2a expression. In conclusion, both sodium selenate and sodium selenite effectively enhanced tobacco salt tolerance. The salt stress alleviation effect of Se(VI) may be associated with upregulating NtNAC2 and NtCDPK12 to improve antioxidant capacity and photosynthesis, thereby potentially maintaining cell membrane integrity and ion balance, while Se(IV) may exert its effect through upregulating NtROS2a to promote root thickening, reactive oxygen species scavenging and osmotic adjustment. At the tested concentrations, selenate was more effective. Full article

Agrivoltaics is an important pathway for promoting the coordinated development of clean energy production and agricultural utilization. However, the structural characteristics of flexible agrivoltaic (AV) systems may significantly alter field light and thermal conditions, while their effects on crop growth and yield formation remain unclear. To address this issue, a flexible AV system in Sihong County, Jiangsu Province, was selected as the study site, and continuous field monitoring combined with crop measurements was used to evaluate changes in microclimate, wheat physiological responses, and yield performance. The results showed that the flexible AV system significantly changed the field microclimate. During the wheat growing season, the monthly average solar radiation intensity under and between PV panels decreased by 62.0% and 56.9%, respectively, compared with that in the open field. The array also showed a certain thermal regulation effect, with heat preservation during the overwintering stage and cooling during the later growth stage. Shading reduced wheat net photosynthetic rate and stomatal conductance, but adaptive responses such as increased leaf area and chlorophyll content were observed. Wheat yield within the flexible AV system was significantly lower than that in the open field, with reductions of 43.4% and 47.2% in 2024 and 41.8% and 44.6% in 2025 for the areas under and between PV panels, respectively. Overall, light reduction under high coverage conditions remained the main factor limiting wheat yield. These results provide a theoretical basis for structural optimization and crop selection in flexible AV systems. Full article

Drought stress is one of the most severe constraints affecting wheat production worldwide. Under these conditions, the development of sustainable and economically viable strategies, such as seed priming, is essential to improve wheat performance and drought resilience. The present study carried out a greenhouse experiment on four Mediterranean durum wheat cultivars (Triticum turgidum ssp. durum Desf), i.e., Karim (Kr) and Khiar (Kh) from Tunisia and Espelta (Esp) and Mocho (Mo) from Spain, subjected to drought stress conditions, and using primed abscisic acid (ABA), indole-3-acetic acid (IAA), melatonin (Mlt), and salicylic acid (SA), and non-primed seeds. In order to assess the physio-biochemical responses of durum wheat, such as plant growth, chlorophyll, relative water content (RWC), water potential (Ψw), osmotic potential (Ψs), proline, soluble sugars, starch, glycine betaine, hydrogen peroxide, malondialdehyde, and antioxidant enzyme activities. The results showed that water stress significantly reduced plant growth, SPAD index, RWC, Ψw, and Ψs, while upregulating H₂O₂ and MDA levels, depending on the wheat cultivars. Soluble sugars decreased, whereas starch, glycine betaine, and proline accumulated in all cultivars. Superoxide dismutase activity was reduced (24–37%) under water stress as compared to the control condition, while APX, CAT, and POD activities significantly increased. Among the cultivars, Esp exhibited the greatest plasticity in response to water deficit, whereas Kh appeared to be most sensitive. Furthermore, the present results revealed that the priming durum wheat seeds with ABA, IAA, Mlt, and SA improved leaf hydration, particularly through soluble sugar accumulation. Seed priming also alleviated oxidative stress by reducing H₂O₂ and MDA levels and stimulating APX, CAT, POD, and SOD activities. Plants grown from non-primed seeds of Spanish and Tunisian cultivars exhibited differential responses to drought stress, and those derived from primed seeds showed varying degrees of enhanced drought tolerance. Espelta demonstrated a high potential for stress tolerance and responsiveness to priming, followed by Karim, whereas Khiar was the most sensitive cultivar. Overall, the cultivars can be ranked in decreasing order of stress tolerance as Esp > Kr > Mo > Kh. These findings highlight the potential of phytohormone-based seed priming as an efficient and practical approach to enhance drought resilience in durum wheat, offering promising prospects for improving crop performance and stability under increasingly water-limited conditions in the era of climate change. Full article

In plant factories with artificial lighting (PFALs), spectral regulation serves as the predominant factor governing plant growth and development. The implementation of red-enriched spectral regimens during cultivation promotes biomass accumulation, whereas blue-dominant spectra enhance the biosynthesis of phytochemicals and nutritional compounds in plants. Nevertheless, systematic investigations into the effects of staged spectral regimens on both plant development and secondary metabolite biosynthesis remain limited. This study evaluated four distinct stage-specific dynamic lighting regimens (T1–T4) under a constant total photosynthetic photon flux density (PPFD) of 200 μmol·m⁻²·s⁻¹. The treatments utilized three distinct red-to-white photon flux ratios (R:W = 3:1, 1:1, and 1:3) administered sequentially during critical developmental phases of Pak choi: the seedling stage, the early growth stage (15 days after transplanting, DAT), and the late growth stage (16–30 DAT). The effects of these treatments on biomass production, morphological development, photosynthetic pigments, nutritional metabolites, antioxidant levels and radical quenching capacity were evaluated. The results demonstrated that the T4 treatment significantly enhanced biomass production, increasing shoot fresh weight by 51.3% compared to the T1 treatment at the late growth stage. The application of a higher red-light proportion (HR, R:W = 3:1) during the seedling stage significantly increased leaf area by 70% compared to the low red-light treatment (LR, R:W = 1:3). Regarding nutritional quality, while carotenoid content showed no significant differences among treatments, higher blue-light proportions selectively stimulated the biosynthesis of chlorophyll, vitamin C, and soluble proteins. Specifically, the T3 treatment enhanced certain traits during the early growth stage, whereas the T2 treatment best maintained specific antioxidant capacities (FRAP and flavonoids) at the late growth stage prior to harvest. Notably, nitrate levels were not significantly affected by the spectral shifts. This study establishes that the temporal modulation of red-to-white spectral ratios enables the targeted optimization of either crop yield (T4) or specific harvest-stage nutritional attributes (T2) in Pak choi. Full article

Drought is a major environmental constraint that disrupts photosynthetic processes. This study investigated the effects of foliar-applied commercial humic acid (HA) at different concentrations (1, 3 and 5 mg/mL) on the photosynthetic apparatus of sweet basil (Ocimum basilicum L. Italiano classico) under PEG-induced stress. The responses of the photosynthetic machinery were evaluated using chlorophyll a fluorescence analyses (JIP-test and PAM), leaf pigment composition, and assessments of membrane integrity. Drought stress caused pronounced alterations on both the donor and acceptor sides of photosystem II (PSII), including impaired Q_A⁻ reoxidation, reduced open PSII reaction centers (qP), diminished electron transport (ETo/RC, REo/RC), and substantial declines in performance indices (PI_ABS, PItotal). Energy dissipation increased (DI₀/RC), with regulated energy losses (Φ_NPQ) rising more strongly than non-regulated losses (Φ_NO). Drought also elevated oxidative stress markers (MDA and H₂O₂), leading to enhanced membrane injury. Among the tested concentrations, 5 mg/mL HA provided the most effective protection against drought stress. This treatment mitigated PEG-induced damage on both PSII donor and acceptor sides and increased the proportion of open reaction centers (qP). Improved PSII photochemistry corresponded with more efficient Q_A⁻ reoxidation, facilitated its interaction with plastoquinone, and caused the overall stabilization of photosynthetic functions under drought. The protective effects of HA were also evident for both PSI subpopulations. The enhanced tolerance was associated with the activation of antioxidant enzymes (CAT, SOD, APX) and the increased levels of anthocyanins and total phenolic content (TPC). In contrast, lower HA concentrations (1 and 3 mg/mL) provided insufficient protection. This study clearly demonstrates that HA enhances drought tolerance in basil in a concentration-dependent manner by protecting the structural and functional integrity of the photosynthetic apparatus, supporting its potential use as a foliar treatment to improve crop resilience under water-limited conditions. Full article

Growth chambers are vital in controlled environment agriculture (CEA), enabling precise regulation of environmental conditions for year-round crop production, especially in urban areas with limited arable land. This study retrofitted a nonfunctional cold room into a plant growth chamber with controlled temperature, humidity, and CO₂ levels to evaluate lettuce (Lactuca sativa) growth under three LED treatments: broad-spectrum white, combined white and far-red, and narrow amber (598 nm). Environmental parameters were controlled at 21 °C during the day and 19 °C at night, with 65% relative humidity, and 800 ppm CO₂. After 40 days, plants under combined white and far-red LEDs produced the tallest shoots (21.8 ± 0.3 cm) and highest leaf count (23.7 ± 0.9). No significant differences were observed among treatments for fresh mass, dry mass, head diameter, or relative chlorophyll content. The findings demonstrated the feasibility of retrofitting a nonfunctional cold room into a controlled environment growth chamber capable of supporting lettuce cultivation under the tested conditions. Full article

Cover crop in orchards is recognized as a sustainable practice that enhances multiple ecosystem services, yet systematic evaluations of different cover crop management models in citrus orchards remain limited. This study investigated the effects of cover crop management models (natural cover crop: T1, Lolium perenne L.: T2, Trifolium repens L.: T3, Vicia villosa Roth: T4, and mixed cover crops: T5) on soil properties, soil CO₂ flux, leaf physiological traits, fruit quality, and yield in a citrus orchard, using clean tillage as a control. Results showed that cover crop management models significantly influenced soil water content, available nitrogen (AN), available phosphorus (AP), and available potassium (AK). The V. villosa model (T4) reduced AN and AP but enhanced leaf chlorophyll (Cl) and nitrogen (N) content. Soil CO₂ flux was significantly higher under T4, and it showed the lowest soil moisture. The results of mantel tests revealed that AP and soil moisture were key drivers of leaf traits, though no significant treatment effects on fruit quality or yield were detected within the two-year experimental period. These findings indicate that cover crop management models rapidly alter soil properties and CO₂ emissions, but longer-term observations are needed to evaluate cascading effects on fruit. This study offers evidence-based soil management solutions and a framework for enhancing multiple ecosystem services in orchards worldwide. Full article

In vertical farming systems, defining suitable lighting strategies is essential for improving crop productivity and product quality under controlled environmental conditions. This study evaluated the effects of four LED lighting configurations differing in spectral composition and lamp-to-canopy distance on the growth and selected quality traits of arugula (Eruca sativa Mill.) grown in a vertical nutrient film technique (NFT) system. Two light spectra were tested: white LED light and a red–blue LED combination, each applied at two distances from the crop canopy (20 and 40 cm). Two experiments were conducted in 2025 in a climate-controlled cultivation unit, and agronomic and quality-related variables were assessed at harvest, including fresh biomass, leaf development, total polyphenols, antioxidant capacity, chlorophyll index, and nitrate concentration. The LW20 treatment, representing a specific combination of white LED lighting, lamp-to-canopy distance, PPFD, and DLI, was associated with the highest fresh biomass, reaching 42.6 g plant⁻¹ in Experiment 1 and 70.9 g plant⁻¹ in Experiment 2, and with the highest total polyphenol content (38.4 mg GAE 100 g⁻¹ FW). In contrast, the red–blue treatments were associated with lower biomass production, while the RB20 treatment showed the lowest polyphenol concentration (26.2 mg GAE 100 g⁻¹ FW). Among the evaluated quality-related parameters, total polyphenols showed the clearest response to lighting conditions, whereas antioxidant capacity, chlorophyll index, and nitrate concentration were not significantly affected. Under the evaluated conditions, LW20 was the most favorable among the four tested lighting configurations for fresh biomass production and total polyphenol accumulation. However, this response should not be interpreted as evidence of white light superiority alone, because spectral composition, lamp-to-canopy distance, PPFD, and DLI were not independently controlled. Full article

Investigating the application of sustainable agricultural approaches, such as the use of biostimulants, is considered more significant than ever, especially in the commercially important species Actinidia deliciosa L., in the face of climate change. In this work, the application of a glycine–betaine–proline-based biostimulant (GBP) and a humic and fulvic acid-based biostimulant (HF) was evaluated on the growth and metabolism of kiwi trees under field conditions. Total phenolic content, proline, and chlorophyll content were analyzed during the experiment. The metabolic data showed that the kiwi trees of the GBP treatment were more robust, as indicated by proline analysis (0.41 ± 0.09 µmol g⁻¹) compared to C (0.28 ± 0.06 µmol g⁻¹). This vigor of GBP treatment was also represented in leaf area (3943.17 ± 211.26 cm²), compared to the C (3484.01 ± 354.19 cm²). The implementation of biostimulants constitutes an ecological approach that can be integrated into biological crop management, as it is environmentally friendly, non-invasive to the ecosystem, and aims for crop resilience to biotic or abiotic stress. Full article

Although soybean is vital to the global economy, this crop faces productivity losses due to photoinhibition of photosystem II (PSII), which is worsened by heat and drought. Carbon dots (Cdots) offer a strategy to mitigate this stress by acting as light-harvesting and UV-protective agents. This study evaluated the foliar application of Cdots on soybean (Glycine max L. Merr. cv. BRS 1054 IPRO) exposed to high light intensity. In a greenhouse experiment with a completely randomized design, plants received deionized water (Control), synthesized Cdots at three concentrations (0.02, 0.05, and 0.20 mg mL⁻¹), or a commercial Cdot product. Plants were grown under 50% shade and, at 24 days after sowing, transferred to a high-light greenhouse (20% attenuation). Measurements included PSII fluorescence (maximum quantum yield, potential activity, basal fluorescence, and dynamic photoinhibition) and leaf gas exchange (stomatal conductance, net photosynthesis, transpiration, intercellular CO₂ concentration, intrinsic water use efficiency, and carboxylation efficiency), as well as chlorophyll index and growth traits. Cdots at 0.05 mg mL⁻¹ and the commercial product maintained higher morning PSII maximum activity (+16% vs. Control), indicating enhanced photoprotection. Conversely, 0.20 mg mL⁻¹ Cdots reduced PSII maximum activity by 62% at noon. At day 14, the 0.05 mg mL⁻¹ treatment improved stress acclimation, reducing stomatal conductance and transpiration, while sustaining photosynthesis. Growth was significantly enhanced at this concentration, increasing chlorophyll content by 14%, shoot length by 26%, and total dry mass by up to 41% compared to controls. In conclusion, Cdots at 0.05 mg mL⁻¹ alleviated chronic photoinhibition without increasing dynamic photoinhibition, thus acting as a promising nanobiostimulant that promotes soybean early growth under high-light stress. Full article

Agronomic biofortification offers an environmentally friendly way to improve crop nutrition. The biofortification of vegetables with iodine has attracted increasing attention due to its significance for human health. Hydrogen sulphide (H₂S) is a gaseous signalling molecule that affects many physiological and biochemical processes in plants. Lettuce (Lactuca sativa L.) plants were cultivated under controlled greenhouse conditions. Foliar applications of potassium iodate (KIO₃) and hydrogen sulphide (H₂S, supplied by sodium hydrosulphide (NaHS)) were applied separately and together (H₂S + KIO₃). Evaluations included growth parameters, photosynthetic pigments, biochemical metabolites, antioxidant enzyme activities, plant hormone levels, and mineral nutrient contents. All treatments resulted in significant changes in plant growth and physiological traits compared to the control. The combined application resulted in greater responses across several parameters; however, these observations do not demonstrate a causal or mechanistic interaction between the treatments. The combined application increased plant fresh weight by ~42% and leaf area by ~35% compared to the control. Total chlorophyll content approximately doubled (≈100% increase), while SOD, POD, and CAT activities increased by up to ~160%, ~13%, and ~40%, respectively. Proline and sucrose contents increased by approximately 100% and 85%. Hormonal changes included increases in indole-3-acetic acid (~44%) and cytokinins (~55%), and a decrease in abscisic acid (~20%). In addition, several macro- and micronutrients in leaves and roots were affected by the treatments. The combined application of KIO₃ and H₂S was associated with greater responses across several measured parameters than either compound alone; however, these observations do not demonstrate a causal or mechanistic interaction between the two compounds. Furthermore, as the experiment was conducted under non-stress greenhouse conditions, the observed physiological responses should be interpreted as changes in metabolic and regulatory processes rather than direct evidence of enhanced stress tolerance. Overall, the results indicate that foliar application of KIO₃ and H₂S can influence growth and physiological traits of lettuce under controlled conditions. Full article

Chromium (Cr) contamination leads to the accumulation of Cr in crops, thereby posing a significant threat to food security and human health. It is essential to comprehend the mechanisms underlying Cr toxicity and to develop effective mitigation strategies to ensure healthy crop growth. Melatonin (MT), a multifunctional regulatory molecule, plays a pivotal role in the response of plants to heavy metal stress. This study is designed to investigate the underlying mechanisms through which exogenous application of MT mitigates the toxicity of Cr stress in maize seedlings. The findings of the study indicate that under Cr stress conditions, treatment with MT significantly decreased the Cr concentrations in the roots and leaves of maize, with reductions of 22% and 28.5%, respectively. Concurrently, MT demonstrated effectiveness in alleviating the toxic effects induced by Cr exposure, as evidenced by substantial improvements in the leaf area, chlorophyll content, and photosynthetic rate, which increased by 40.3%, 47.7%, and 64.8%, respectively. This led to a 42.2% increase in the total dry weight of maize. Further analysis indicates that MT modulates the antioxidant system, thereby reducing the production of reactive oxygen species and reducing membrane lipid damage associated with Cr toxicity. Moreover, MT upregulates the expression and activity of enzymes involved in polyamine synthesis while simultaneously inhibiting the activity of polyamine-degrading enzymes, leading to a 38% increase in total polyamine content. This study has enhanced our understanding of the mechanisms through which melatonin alleviates chromium toxicity in crops and has provided a theoretical foundation for its sustainable application in agricultural production. Full article

Agroforestry systems with live stakes have been proposed as management strategies to enhance soil and canopy-related processes in perennial crops. However, their integrated effects on productivity under Amazonian conditions remain poorly understood. This study evaluated the role of live stakes as modulators of soil and canopy conditions in Hylocereus undatus cultivated in the Ecuadorian Amazon. The field study lasted three years and used live stakes (Spondias mombin and Erythrina sp.) and an inert concrete stake. S. mombin exhibited the highest annual biomass contribution (14 t ha⁻¹ year⁻¹), approximately double that of Erythrina sp., and a higher abundance of earthworms (20 individuals m⁻²), suggesting greater soil biological activity. Canopy-mediated conditions differed among stake systems, with shade levels progressively increasing over time and reaching up to 67% under S. mombin. However, the crop’s physiological response, assessed through leaf relative chlorophyll content, was dominated by seasonal variability and did not show structural differences among the systems. Yield was comparable between S. mombin and the inert stake (18–20 t ha⁻¹) and lower under Erythrina sp. (14 t ha⁻¹). Overall, live stakes influenced system functioning, defined here as the combined response of soil biological indicators (earthworm abundance) and canopy-related indicators (shade percentage and relative chlorophyll content) in relation to yield. Although these effects did not translate into increased yield under the evaluated conditions, they may contribute to improvements in soil quality and biological activity over longer time scales. Full article

The sustainable valorization of marine biowaste, particularly shrimp residues, has emerged as a promising strategy to develop eco-friendly agricultural inputs that enhance crop productivity and reduce environmental impacts. This study investigated the effects of a biotechnologically processed fermented shrimp-waste (Parapenaeus longirostris) formulation as a biostimulant on the growth, physiological performance, and development of a local mays variety (Zea mays L., DKC 744) under controlled pot conditions. The experiment evaluated root, foliar, and combined applications of the biostimulant at three concentrations (5%, 10%, and 15%) over a 90-day vegetative cycle. Morphological parameters, including stem height, leaf number, leaf mass, and root biomass, were measured at regular intervals, while chlorophyll a and b contents were assessed to evaluate photosynthetic efficiency. The results indicated that all biostimulant treatments significantly enhanced mays growth. Root-applied biostimulants primarily stimulated root biomass by up to 764.0 ± 66.8 g at the 10% concentration, whereas foliar applications improved above-ground traits, including stem elongation and leaf formation, reaching maximum heights of 200.0 ± 1.9 cm and 17.0 ± 0.4 leaves under intermediate concentrations. Combined root and foliar applications produced the highest stem height (240.0 ± 5.6 cm), leaf number (19.0 ± 0.0), leaf mass (1034.0 ± 11.1 g), and chlorophyll content (2.44 ± 0.9 for chlorophyll a) at 10–15% concentrations. The results also revealed that moderate concentrations generally provided the most balanced stimulation, suggesting the presence of an optimal dose threshold. This study demonstrated the comparative effectiveness of root, foliar, and combined applications of a fermented shrimp-waste biostimulant and identified an optimal concentration. However, its limitations lie in the use of controlled pot conditions and a single crop variety, which restrict the extrapolation of results to field-scale applications and diverse agroecological environments. Therefore, more research is needed to explore the action mechanisms of the studied biostimulant and elicitors, mainly the interaction between biocompounds and the treated plant. Full article