Search Results (5,739)

Cowpea (Vigna unguiculata L. Walp.) is a species with superior tolerance to drought stress compared to other legumes. It is a promising crop with increasing importance in the face of global climate changes. Local forms, well adapted to particular agro-climatic conditions, are useful germplasm resources. Five Bulgarian cowpea landraces, which had displayed differences in osmotic stress tolerance at the germination stage, were subjected to severe stress (15% PEG 6000 in Hoagland nutrient media) during 16 days at the vegetative growth stage (plants with expanded trifoliate leaves). All local forms responded to the imposed stress by biomass and leaf area diminution, a slight increase in leaf water deficit and electrolyte leakage, proline accumulation in roots and leaves, and an increase in root starch and leaf phenol content. Roots presented more pronounced metabolic changes than leaves, including increased total antioxidant activity, phenolic and carbohydrate content, and proline accumulation. Under osmotic stress, tight control of oxidative stress and concerted upregulation of superoxide dismutase, catalase, glutathione transferase, and peroxidase activities in leaves were registered along with changes in certain specific isoforms, while glutathione reductase activity diminished. Antioxidant enzyme activities had different changes in stressed roots, compared to leaves, and among genotypes. The accession most sensitive to osmotic stress at germination presented more symptoms of oxidative stress at the vegetative growth stage. Full article

The application of marine algae-derived biostimulants offers a sustainable approach to improving plant performance in aromatic and medicinal crops. This study investigated the effects of four macroalgal extracts and two commercial biostimulant products on the growth, physiology, and essential oil production of Lavandula angustifolia cultivated under greenhouse conditions at CREA, Pescia (Italy). Treatments included extracts from Ascophyllum nodosum (France and Greenland), Laminaria digitata (Iceland), Sargassum muticum (Italy), two commercial formulations (a seaweed-based and an amino acid-based biostimulant), and a control receiving only standard fertilization. Over a 10-week period, plants were evaluated for multiple parameters: plant height, leaf number and area, SPAD index (chlorophyll content), above- and below-ground biomass, flower production, microbial activity in the growth substrate, and essential oil yield. Algae extracts, particularly those from A. nodosum (Greenland) and S. muticum (Venice), significantly enhanced most parameters compared to the control and commercial products. These treatments yielded higher biomass, greater chlorophyll retention, increased flower number, and improved essential oil content. Rhizosphere microbial counts were also elevated, indicating a positive interaction between algae treatments and substrate biology. The study highlights the multifunctional nature of marine algae, whose complex composition of bioactive compounds appears to promote plant growth and secondary metabolism through multiple pathways. The superior performance of cold- and temperate-climate algae suggests a relationship between environmental origin and biostimulant efficacy. Compared to commercial inputs, the tested algae extracts showed broader and more consistent effects. These findings support the integration of macroalgae-based biostimulants into sustainable lavender cultivation strategies. Further research is recommended to optimize formulations, validate field performance, and explore synergistic effects with beneficial microbes or organic inputs. Full article

Studies exploring the competitive interactions between common beans and weeds are essential to adopt more efficient management strategies in the field, thereby reducing production costs. This study aimed to evaluate the competitive ability of bean cultivars in the presence of sourgrass (Digitaria insularis), using different plant proportions in associations. The experiments were conducted in a greenhouse, arranged in a randomized block design with four replications, from October 2020 to February 2021. Treatments were organized in the following plant proportions of beans and sourgrass: 100:0, 75:25, 50:50, 25:75, and 0:100%. The competitiveness analysis was carried out using replacement series diagrams and relative competitiveness indices. At 50 days after emergence (DAE), measurements were taken for leaf area, plant height, gas exchange, shoot dry mass, and nutrient concentration in bean leaves. The results show that interference between common bean cultivars and sourgrass involves equivalent competition mechanisms. Increasing sourgrass density negatively affects physiological traits and gas exchange in beans by about 10%. Beans show about 15% higher relative growth than sourgrass, based on competitiveness indices. Nutrient levels vary by cultivar and competitor ratio. Intercropping harms species more than intraspecific competition. Further field studies should determine critical control stages and economic impacts, aiding weed management decisions in bean production. Full article

Indonesia has 13.43 million hectares of tropical peatlands, the largest in Southeast Asia, which are crucial for carbon sequestration. This function is influenced by vegetation nutrient content, particularly carbon (C), nitrogen (N), phosphorus (P), and potassium (K), which regulate biogeochemical cycles and peat formation. This study analyzed stoichiometric profiles of tree species in South Sumatra peatlands based on (1) C:N ratios across roots, stems, twigs, and leaves, and identified species with traits associated with high carbon sequestration potential, and (2) leaf N:P:K stoichiometry to infer nutrient limitations. Research was conducted in a 1-hectare primary peatland plot within the PT. Tri Pupa Jaya conservation area. C, N, P, and K contents were measured using Kjeldahl distillation, spectrophotometry, flame photometry, and the Walkley–Black method following acid digestion. Stoichiometric distribution was visualized with violin-box plots and species grouped through hierarchical clustering. Among 153 identified species, stems showed the highest mean C:N ratio (314.9 ± 210.8), while leaves had the lowest (29.7 ± 13.0). Species were grouped into three clusters by C:N ratios across four organs, with six in clusters 1 and 2 showing high carbon sequestration potential. Leaf N:P:K stoichiometry suggested nitrogen, phosphorus, or combined N + P limitations. Full article

The photochemical efficiency of photosystem II (PSII) was monitored in two-year-old seedlings from six Chilean woody sclerophyllous species differing in foliage habits (evergreen, deciduous, semi-deciduous) and leaf orientation. A common garden experiment was established in July 2020 in a Mediterranean-type climate site under two watering regimes (2 L⁻¹ seedling⁻¹ week⁻¹ for 5 months versus no irrigation). Chlorophyll a fluorescence rise kinetics (OJIP) and JIP test analysis were monitored from December 2021 to January 2022. The semi-deciduous Colliguaja odorifera (leaf angle of 65°) exhibited the highest performance in processes such as absorption and trapping photons, heat dissipation, electron transport, and level of photosynthetic performance (i.e., parameters PI_ABS F_V/F_M, F_V/F₀, and ΔV_IP). In contrast, the evergreen Peumus boldus (leaf rolling) exhibited the opposite behavior for the same parameters. On the other hand, the deciduous Vachelia caven (small compound leaves and leaf angle of 15°) showed the lowest values for minimal and maximal fluorescence (F₀ and F_M) and the highest area above the OJIP transient (S_m) during the study period. Irrigation decreased S_m and the relative contribution of electron transport (parameter ΔV_IP) by 22% and 17%, respectively, but no clear effects of the irrigation treatments were observed among species and dates of measurement. Overall, V. caven and C. odorifera exhibited the highest photosynthetic performance, whereas P. boldus seemed to be more prone to photoinhibition. We conclude that different foliar adaptations among species influence light protection mechanisms more than irrigation treatments. Full article

The pathogenic plant fungus Bipolaris maydis is responsible for southern corn leaf blight (SCLB), a widespread agricultural disease that significantly reduces maize yield in various agroecological zones. The present research focuses on characterizing the role of Trichoderma harzianum cellobiohydrolase (CBH) Thph2 in induced maize resistance to SCLB by triggering the production of reactive oxygen species (ROS) in leaves. First of all, we demonstrated the potential activities of Thph2 in triggering ROS burst and PDC in a model plant, Nicotiana benthamiana. Cell death, ROS burst, and programmed cell death (PCD) were observed in N. benthamiana leaves following transient expression of Thph2, indicating its defensive role against Sclerotinia sclerotiorum infection. The removal of the signal peptide from Thph2 resulted in the complete loss of the cell death phenotype and the accumulation of reactive oxygen species (ROS), confirming that Thph2 functions as a microbial elicitor that primes host plant immunity through ROS-mediated signaling, thereby inducing systemic resistance (ISR). Furthermore, the Thph2 protein conferred resistance against B. maydis in maize, significantly increasing reactive oxygen species (ROS) accumulation (1.5-fold compared to the control) at 48 h post-inoculation (hpi),and leading to the reduction in the lesion area of SCLB by 15.9% at 2 days post-inoculation (dpi). Our results demonstrated that the Thph2 protein markedly enhanced the expression of lox5, aos, and hpl in maize leaves, thereby confirming its function in triggering plant defense mechanisms primarily via the jasmonic acid signaling pathway. This research reveals new molecular mechanisms by which T. harzianum enhances plant defense and showcases the biocontrol efficacy of Thph2 against southern corn leaf blight (SCLB). Full article

Hyperspectral imaging (HSI) technology has attracted extensive attention in the field of nutrient diagnosis for rubber leaves. However, the mainstream method of extracting leaf average spectra ignores the leaf spatial information in hyperspectral imaging and dilutes the response characteristics exhibited by nutrient-sensitive local areas of leaves, thereby limiting the accuracy of modeling. This study proposes a spatial–spectral feature fusion method based on leaf-scale sub-region segmentation. It introduces a clustering algorithm to divide leaf pixel spectra into several subclasses, and segments sub-regions on the leaf surface based on clustering results. By optimizing the modeling contribution weights of leaf sub-regions, it improves the modeling and generalization accuracy of potassium diagnosis for rubber leaves. Experiments have been carried out to verify the proposed method, which is based on spatial–spectral feature fusion to outperform those of average spectral modeling. Specifically, after pixel-level MSC preprocessing, when the spectra of rubber leaf pixel regions were clustered into nine subsets, the diagnostic accuracy of potassium content in rubber leaves reached 0.97, which is better than the 0.87 achieved by average spectral modeling. Additionally, precision, macro-F1, and macro-recall all reached 0.97, which is superior to the results of average spectral modeling. Moreover, the proposed method is also superior to the spatial–spectral feature fusion method that integrates texture features. The visualization results of leaf sub-region weights showed that strengthening the modeling contribution of leaf edge regions is conducive to improving the diagnostic accuracy of potassium in rubber leaves, which is consistent with the response pattern of leaves to potassium. Full article

Intra-specific variation in functional traits and their inter-relationships reflect how plants allocate resources, adapt, and evolve in response to environmental changes. This study investigated eight functional traits—leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC), chlorophyll content (CHL), leaf nitrogen content (LNC), leaf phosphorus content (LPC), twig tissue density (TTD), and wood density (WD)—in Cunninghamia lanceolata plantations of three stand ages (15, 30, and 50 years), using a space-for-time substitution approach. We examined differences in trait values, intra-specific variation, and trait correlations across forest ages and diameter classes. The results showed that (1) Functional traits exhibited varying degrees of intra-specific variation, with LA having the highest coefficient of variation (21.66%) and LPC is lowest (9.31%). (2) Forest age had a stronger influence on trait variation than diameter class, with all traits differing significantly across ages, while only WD varied significantly among diameter classes. (3) PC1 (25.5%) and PC2 (19.4%) together explained approximately 44.9% of the total variation, with PC1 primarily reflecting functional trait changes driven by forest age. PCA results showed that LA and CHL tended to exhibit higher values in young forests, whereas SLA, LDMC, LPC, and LNC had relatively higher values in mature forests. This pattern suggests a shift in functional trait expression from resource acquisition to resource conservation strategies with increasing forest age. (4) Significant positive correlations between LNC and LPC, and negative correlations between SLA and LDMC, were observed in most groups, except in large-diameter trees at the over-mature stage. C. lanceolata adjusts trait combinations to enhance fitness across developmental stages. Juvenile trees adopt traits favoring efficient light and nutrient use to support rapid growth and competition. Middle-aged trees prioritize balanced water and nutrient use to maintain productivity and resist disturbances. Mature trees focus on sustained resource use and offspring protection to support ecosystem stability and regeneration. These findings reveal age-specific adaptive strategies and provide insights into the coordination and trade-offs among traits in response to environmental conditions. Full article

Curvularia lunata (Wakkre) Boedijn is an important pathogenic fungus that causes maize leaf spot, a prevalent disease that caused significant yield losses in maize-growing areas in China in the 1990s. Clpks18, a polyketide synthase (CLPKS18) gene, has been identified as a crucial virulence-related gene in C. lunata. However, the impact of Clpks18 and its biosynthesized virulence factor (R)-(-)-mellein on the expression of maize genes related to the defense signal pathway has never been determined. In this study, it was found that Clpks18 and (R)-(-)-mellein significantly interfere with the signaling pathways of JA and IAA in maize leaves but in different ways and in a time-dependent manner. While CLPKS18 inhibited the maize’s JA and IAA signaling pathways through its related secondary metabolite, (R)-(-)-mellein inhibited the JA signaling pathway but stimulated IAA accumulation in maize leaves. In summary, understanding this novel virulence effector’s mechanism of interference with maize resistance enriches the pathology of Curvularia leaf spot in maize on the one hand and provides a foundation for screening the resistance germplasm and chemical fungicides against the disease on the other. Full article

A large population in Africa, particularly West Africa, depends on leafy vegetables such as red amaranth (Amaranthus cruentus), Lagos spinach (Celosia argentea), and African eggplant (Solanum macrocarpon) as affordable and readily available sources of nutrition. These vegetables are rich sources of phenolics, minerals, vitamins, and bioactive compounds, contributing significantly to dietary nutrition and providing an important source of revenue for farmers. However, the temperature rise due to climate change threatens their availability and nutritional value. This study assessed the effects of temperature regimes (23, 30, and 40 °C) on the growth and quality of these vegetables under greenhouse conditions for 48 (A. cruentus and C. argentea) and 54 (S. macrocarpon) days after sowing by measuring biomass (leaf, stem, shoot, root dry weight, root/shoot and leaf area), photosynthetic parameters, pigments, sugars, mineral content, antioxidant activity, total phenolic compounds, total flavonoids, and free amino acids. Temperature significantly affected biomass, with A. cruentus and C. argentea showing declines of 13.5–32.2% and 5.1–27.8%, respectively, at 40 °C compared to 23 °C, indicating sensitivity to heat stress. Photosynthetic rates increased with a rise from 23 to 30 °C by 2.1–29.2% across all species. Sugar contents remained generally stable, except for notable decreases in glucose and soluble sugars by 43.3% and 40.5%, respectively, in C. argentea between 30 and 40 °C, and a 52.6% reduction in starch in S. macrocarpon from 23 to 40 °C. Mineral nutrient responses varied by species; however, they exhibited similar increases in nitrogen and phosphorus, as well as decreases in calcium and manganese, at higher temperatures. Notably, antioxidant capacity and total phenolic compounds declined significantly in C. argentea (8.1% and 8.0%) and S. macrocarpon (4.7% and 13.3%). In contrast, free amino acid contents increased by 35.2% and 28.8% in A. cruentus and S. macrocarpon, respectively. It was concluded that A. cruentus and C. argentea suffer reduced growth and nutrients at 40 °C, while S. macrocarpon maintains biomass but has some biochemical declines; antioxidant capacity and phenolics drop at high temperatures, free amino acids rise, and 30 °C is optimal for all three. Full article

An appropriate drip irrigation amount and the straw return method are important ways to save water and achieve efficient maize production in semi-arid areas. A 2-year controlled field plot experiment was performed with two factors: straw return (straw removal, straw mulching) and differing drip irrigation amounts (200, 350, and 500 mm). Changes in growth, development, photosynthesis, yield, the components, and the water-use characteristics of maize under the intercropping conditions of drip irrigation amount and straw return were studied. The results showed that an increase in drip irrigation favored an increase in the net photosynthetic rate (P_n), stomatal conductance (G_s), and intercellular carbon dioxide concentration (C_i) of maize, and promoted an increase in maize plant height and leaf area index, which resulted in the accumulation of more dry matter and increased the maize yield. Compared with straw removal, straw mulching maintained a higher photosynthetic capacity at the later stages of maize growth and development under irrigations of 200 and 350 mm; the average increase in P_n over two years ranged from 4.06 to 19.19%; and good plant growth was maintained, thereby leading to the accumulation of more dry matter, with the average increase over two years ranging from 0.51 to 27.22%. Straw mulching also significantly improved water-use efficiency (WUE) at 350 mm of irrigation, with the average increase in yield over two years ranging from 4.58 to 4.83%. Overall, straw mulching had a positive impact on maize when irrigation was low, and when it was high, straw mulching did not adversely affect maize. Therefore, irrigation combined with straw mulching technology may be used to improve maize yield and WUE in semi-arid areas of Jilin Province. Full article

Low inner leaves in the thick canopy of dense Chinese fir plantations frequently show premature senescence and dieback regardless of age. To elucidate the underlying mechanisms, a 28-day growth chamber experiment was conducted under dark conditions to induce leaf senescence. Changes in leaf area, photosynthetic performance, and the responses of carbon metabolism and the antioxidant defense system were analyzed. Leaf area decreased significantly with time in darkness. The photosystem II reaction center was damaged, and fluorescence parameters and chlorophyll contents decreased, resulting in reduced light energy capture and conversion efficiencies. Photosynthetic rate, apparent quantum yield, stomatal conductance, transpiration rate, and light use efficiency all decreased, while the light compensation point and intercellular CO₂ concentration increased. Antioxidant enzyme activities initially increased but eventually collapsed as the stress continued and H₂O₂ and malondialdehyde accumulated, causing membrane conductivity, i.e., membrane permeability, to increase by 122%. Meanwhile, reduced non-structural carbohydrates, especially total non-structural carbohydrates content, decreased by 45.32%, triggering sugar starvation and accelerating aging. Our study provided new physiological evidence for light-stress response mechanisms in Chinese fir. Specifically, it revealed that dark-induced leaf senescence was mainly caused by irreversible damage to the photosynthetic apparatus and oxidative stress, which together led to carbon starvation and ultimately death. Full article

Salt stress is a major abiotic factor that inhibits plant growth. Melatonin (MT), an important plant growth regulator, can effectively enhance plant stress resistance. Festuca elata, a turfgrass species widely used in urban landscaping, was selected for this study to evaluate the regulatory effects of exogenous MT at different concentrations on its growth and development under salt stress. Indoor pot experiments were conducted using Festuca elata as the plant material. The experiment included a 250 mM NaCl salt-stress treatment and foliar application of five MT concentrations (0 μM, 50 μM, 150 μM, 250 μM, and 350 μM) to assess their effects under salt stress. The results showed that salt stress severely inhibited the growth of Festuca elata, while all tested MT concentrations significantly alleviated the damage. MT treatments improved leaf area and plant height and increased relative water content, soluble protein, proline, chlorophyll, and carotenoid contents. Additionally, MT reduced malondialdehyde accumulation and enhanced superoxide dismutase and peroxidase activities. Among the tested concentrations, 150 μM MT showed the most effective alleviation of salt stress, indicating its strong potential for promoting Festuca elata cultivation in saline environments. Full article

Bonellia nervosa is an understory tree with reverse phenology in tropical dry forests (TDFs), where seasonal water and temperature stress typically shape plant phenology and trait expression. This species is heliophytic and phreatophytic, relying on high light availability and deep-water access during the dry season. However, the role of dry-season light variation in influencing leaf traits of species with inverted phenology remains poorly understood. We examined how plant size, reproductive stage, and canopy structure influence trait variation in B. nervosa during the dry season. We measured plant height and diameter, reproductive status, and canopy structure using hemispherical photographs to estimate canopy openness, leaf area index, and transmitted light. Leaf structural traits included specific leaf area (SLA), thickness, water content, and stomatal density, while photochemical performance was assessed via chlorophyll fluorescence and rapid light curves. Principal component analysis and linear regression were used to examine trait–environment relationships. Photosynthetic efficiency was not affected by plant size or reproductive status. No strong trait correlations were observed for leaf water content and stomatal density. A negative relationship between canopy openness, transmitted light, and SLA indicates structural leaf adaptation to light conditions, with lower SLA values occurring under reduced light. In B. nervosa, leaf traits are driven more by light than by water availability during the dry season. This suggests that reverse phenology in phreatophytic species is functionally decoupled from seasonal water stress. Full article

Efficient use of nitrogen and phosphorus is crucial for achieving sustainable wheat production. Slow-release nano-fertilizers offer a targeted strategy to minimize nutrient losses, reduce excessive fertilizer application, and improve crop yield. This study introduces urea–hydroxyapatite (n-UHA) nanohybrid as a slow-release fertilizer synthesized to enhance nitrogen (N) and phosphorus (P) delivery efficiency in wheat (Triticum aestivum L.). Physical characterization techniques, including Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), Zetasizer, and Fourier Transform Infrared Spectroscopy (FTIR), confirmed the formation of spherical n-UHA with a particle size of 106 nm. FTIR results indicated the formation of physically bound urea as a coating layer on the particle surface. Foliar application of n-UHA at 2500 and 5000 ppm N significantly increased tiller intensity and grain yield compared to conventional urea. The highest biological yield, approximately 16 t ha⁻¹, was achieved with 5000 ppm n-UHA plus supplemental soil phosphorus (P), representing a 4-fold increase over the control. Conventional urea treatments, in comparison, only doubled yield. Notably, increasing conventional urea concentration from 2500 to 5000 ppm N did not significantly increase the yield even with additional P-soil supplement, while applying 5000 ppm N from n-UHA with supplemental P provided an approximate 25% yield increase compared to 2500 ppm n-UHA without P. The n-UHA’s slow-release mechanism supported prolonged tiller intensity, enhanced protein content, and higher biomass yield and chlorophyll content. This study showed that the slow-release mechanism of urea in the monohybrid due to hydrolysis resulted in localized acidity from carbonic acid production on the leaf surface area and contributed to dissociating phosphate ions from hydroxyapatite, making phosphorous more accessible. The enhanced performance of n-UHA is due to its controlled nutrient release, enabled by the physical binding of urea with hydroxyapatite nanoparticles. This binding ensures a synchronized supply of nitrogen and phosphorus aligned with plant demand. The nano-hydroxyapatite composite (N/Ca 6:1) supplies balanced nutrients via efficient stomatal absorption and gradual release. As an eco-friendly alternative to conventional fertilizers, n-UHA improves nitrogen delivery efficiency and reduces N-evaporation, supporting sustainable agriculture. Full article