Search Results (238)

Maize–soybean intercropping is widely practised to improve land use efficiency, but shading from maize often limits soybean growth and productivity. Melatonin, a plant signaling molecule with antioxidant and growth-regulating properties, has shown potential in mitigating various abiotic stresses, including low light. This study investigated the efficacy of applying foliar melatonin (MT) to enhance shade tolerance and yield performance of soybean under intercropping. Four melatonin concentrations (0, 50, 100, and 150 µM) were applied to soybean grown under mono- and intercropping systems. The results showed that intercropping significantly reduced growth, photosynthetic activity, and yield-related traits. However, the MT application, particularly at 100 µM (MT₁₀₀), effectively mitigated these declines. MT₁₀₀ improved plant height (by up to 32%), leaf area (8%), internode length (up to 41%), grain yield (32%), and biomass dry matter (30%) compared to untreated intercropped plants. It also enhanced SPAD chlorophyll values, photosynthetic rate, stomatal conductance, chlorophyll fluorescence parameters such as Photosystem II efficiency (ɸPSII), maximum PSII quantum yield (Fv/Fm), photochemical quenching (qp), electron transport rate (ETR), Rubisco activity, and soluble protein content. These findings suggest that foliar application of melatonin, especially at 100 µM, can improve shade resilience in soybean by enhancing physiological and biochemical performance, offering a practical strategy for optimizing productivity in intercropping systems. 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

Soybean mosaic virus (SMV) causes systemic infections in soybean plants, leading to chlorotic mosaic and significant yield losses. In Argentina, during the 1990s, three isolates were collected in Marcos Juárez (MJ), Manfredi (M), and Northwestern Argentina (NOA), along with the “Planta Vinosa” (PV) isolate, which causes severe necrosis in some cultivars. These isolates were freeze-dried and stored at −70 °C for several years. They were recovered by mechanical inoculation and biologically, molecularly, and physiologically characterized for the first time. Three of the four isolates showed low genetic divergence in the P1, CI, and CP genes. Although SMV-NOA and SMV-PV had high nucleotide sequence identity, they differed in pathogenicity, seed mottling, and transmission efficiency by seeds or aphids. SMV-NOA caused early changes in photosystem II quantum efficiency (ɸPSII) and malondialdehyde (MDA) content before symptom expression (BS). After symptom development (LS), SMV-M significantly increased MDA, total soluble sugars, and starch compared to the other isolates. Thus, early changes in ɸPSII and sugars may influence late viral symptoms. Likewise, SMV-MJ induced more severe symptoms in the susceptible Davis cultivar than in Don Mario 4800. Therefore, our results demonstrate genomic, biological, and physiological differences among SMV isolates and variable interactions of SMV-MJ with two soybean cultivars. Full article

Aeroponics efficiently conserves water and fertilizer but faces energy sustainability challenges in maintaining high productivity and quality. This study aimed to identify critical growth phases of lettuce affected by management modes and assess resource/energy efficiency (cost per unit yield) to inform the development of sustainability strategies for lettuce production in a lettuce-dominant aeroponics system integrated with radish. Three management modes were tested: M1 (constant nutrient solution concentrations), M2 (variable nutrient solution concentrations), and M3 (combined variable nutrient solution concentrations and preharvest short-duration continuous light for 48 h). Plant parameters were dynamically measured in a 30-day cultivation cycle. The results showed that the intercropped lettuce exhibited peak growth at 15–25 days after transplanting, and nutrient solution adjustment enhanced the shoot weight and quality, with synergistic quality improvements under M3. However, preharvest lighting reduced the net photosynthetic rate via stomatal closure and lowered the effective quantum yield of photosystem II, preventing biomass increase. The preharvest short-duration continuous light elevated the soluble protein, ascorbic acid, and soluble sugar contents. For yield-focused systems, M2 alone achieved comparable shoot weight to M3 with higher energy efficiency. However, when simultaneously considering lettuce quality enhancement and the yield boost of radish in the intercropping system, M3 demonstrated potential for greater marginal benefits. Full article

Microplastics and invasive species, driven by anthropogenic activities, significantly disrupt ecosystems and microbial communities. This study investigated the interactive effects of biodegradable microplastics (polylactic acid, or PLA, and polyhydroxyalkanoates, or PHAs) and the fungal pathogen Rhizoctonia solani on the invasive plant Solidago canadensis. One plant of Solidago canadensis/pot was cultivated in forest soil amended with 1% (w/w) microplastics and/or R. solani. PLA exhibited greater toxicity than PHAs, reducing the plant height, root length, and biomass by 68%, 44%, and 70%, respectively. Microplastics impaired the maximum quantum yield of photosystem II more severely than R. solani. However, S. canadensis demonstrated adaptive antioxidative and extracellular enzymatic mechanisms under combined stresses. A heatmap analysis revealed a positive correlation between PHAs and plant growth traits, while a redundancy analysis explained the 15.96% and 4.19% variability for the first two components (r² = 0.95). A structural equation model indicated the negative effects of morphology and physiology on biomass (β = −1.694 and β = −0.932; p < 0.001), countered by positive antioxidant contributions (β = 1.296; p < 0.001). These findings highlight complex interactions among microplastics, pathogens, and invasive species, offering insights into ecological management strategies under dual environmental pressures. Future studies should assess the long-term field effects and microbial mediation of these interactions. Full article

Hydroponic cultivation offers a promising solution to water scarcity by using less water than traditional soil-based agriculture. Although the integration of silicon (Si) in hydroponic systems is still limited, its foliar application is crucial for optimizing plant growth, enhancing resilience, and improving productivity. Therefore, this study aims to explore the effects of silicon foliar application on growth, yield parameters, and photosynthetic activity of one of the most important fruit vegetables worldwide—tomatoes (Solanum lycopersicum L.)—cultivated in a closed hydroponic system. Tomato plants were subjected to a weekly silicon foliar spray (1 mM Na₂SiO₃) over a period of 10 weeks. Our results demonstrate that silicon foliar spray in hydroponically grown tomatoes significantly improved photosynthetic pigment concentration and enhanced the photochemical efficiency of the photosystems, particularly the quantum yields Y(I) and Y(II). Moreover, silicon treatment resulted in reduced energy dissipation within the photosystems, as indicated by decreases in Y(NPQ), Y(NO), and Y(ND), along with enhanced oxidation of PSI (P700ox). These physiological improvements were directly linked to increased stem width and length, and a substantial boost in plant dry weight compared with untreated controls. Consequently, the silicon foliar spray resulted in a significant increase in the number of racemes, flowers, and fruits. Ultimately, these enhancements culminated in a 69% increase in fruit biomass yield (r² = 0.70; p < 0.01), highlighting the positive impact of silicon on tomato productivity in hydroponic systems. These findings suggest that silicon foliar application optimizes growth and photosynthetic efficiency while reducing energy dissipation. Consequently, silicon supplementation enhances tomato productivity in hydroponic systems, offering a promising solution for increasing yields in water-efficient agriculture. Full article

Salinity stress is a major environmental challenge that adversely impacts the physiological and biochemical processes of pasture, consequently resulting in reduced yields and compromised quality. Biochar amendment has recently emerged as a promising strategy to alleviate the deleterious effects of salinity stress. However, the interactive influences of salinity stress and wheat straw biochar on the physiological, biochemical, and growth characteristics of alfalfa (Medicago sativa L.) remain underexplored. A factorial experiment was conducted using a randomized complete design with five salinity levels (0, 25, 50, 75, and 100 mM NaCl) and three application rates of biochar (0, 25, and 50 g kg⁻¹) to evaluate wheat straw biochar’s potential in alleviating salinity stress in alfalfa. Results showed that salinity stress increased oxidative stress (hydrogen peroxide and malondialdehyde) and reduced chlorophyll fluorescence (maximum quantum efficiency of photosystem II by 1–27%), leading to decreasing photosynthetic parameters, thereby constraining biomass accumulation by 9–77%. Wheat straw biochar amendment under the highest salinity stress, particularly at 25 g kg⁻¹, mitigated oxidative stress by reducing H₂O₂ and MDA levels by 35% and 33%, respectively, while decreasing the antioxidant enzymes activities of CAT, POD, and SOD by 47%, 42%, and 39%, respectively, compared to the control (non-biochar addition). Concurrently, biochar restored the osmoregulatory substance concentrations of proline and soluble sugar by 59% and 33%, respectively, compared to the control. Furthermore, wheat straw biochar amendment increased the net CO₂ assimilation rate by 98%, thereby increasing biomass by 63%. Our study demonstrates that wheat straw biochar can contribute to protecting alfalfa against salinity stress by modulating physiological and biochemical responses. These findings demonstrate that the 25 g kg⁻¹ wheat straw biochar application had the best performance, suggesting this amendment could be a viable strategy for improving alfalfa productivity in salt-affected soils. Future research should explore long-term field applications and the underlying mechanisms of biochar–plant–soil–plant interactions under diverse saline-alkali environments. Full article

Drought significantly constrains common bean (Phaseolus vulgaris L.) production worldwide, and as climate change intensifies, projections indicate a subsequent reduction in yield. This study aimed to identify drought-resilient genotypes among twenty common bean lines in Chile under two water regimes: regular irrigation and terminal drought stress. The research was conducted over two seasons in south-central Chile. Drought significantly reduced grain yield (22.7%), aboveground biomass (37%), harvest index (19.5%), the number of grains per pod (61.3%), and hundred-grain weight (10.1%). Genotypes 452, 473, and 483 exhibited minimal yield reductions (<11%) and maintained stable physiological performance, including higher quantum yield of photosystem II and efficient photoprotective mechanisms (increased ΦNPQ) under stress. In contrast, sensitive genotypes like Blanco Español showed marked yield loss (54%) and lower photosynthetic efficiency. Chlorophyll retention emerged as a key trait for identifying high-yielding, drought-tolerant genotypes. Drought also accelerated crop maturation in susceptible genotypes, compromising yield potential. These findings highlight the importance of integrating agronomic, phenological, and physiological traits in breeding programs to develop drought-adapted varieties. The tolerant genotypes offer valuable genetic traits to improve drought resilience and contribute to food security in the face of climate change. Full article

Salt stress severely impairs photosynthesis and development in tomato seedlings. This study investigated the regulatory role of exogenous melatonin (MT) on photosynthetic performance under salt stress by determining chlorophyll content, chlorophyll a fluorescence parameters, Calvin cycle enzyme activities, and related gene expression. Results showed that salt stress significantly reduced chlorophyll content and impaired photosystem II (PSII) functionality, as evidenced by the increased minimum fluorescence (F_o) and decreased maximum quantum efficiency of PSII (F_v/F_m) and effective PSII quantum yield (Φ_PSII). MT application mitigated these negative effects, as reflected by higher F_v/F_m, increased chlorophyll content, and lower non-photochemical quenching (NPQ). In addition, MT-treated plants exhibited improved PSII electron transport and more efficient use of absorbed light energy, as shown by elevated Φ_PSII and qP values. These changes suggest improved PSII functional stability and reduced excess thermal energy dissipation. Furthermore, MT significantly enhanced both the activity and expression of key enzymes involved in the Calvin cycle, including ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), Rubisco activase (RCA), phosphoglycerate kinase (PGK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), fructose-1,6-bisphosphatase (FBPase), fructose-bisphosphate aldolase (FBA), transketolase (TK), and sedoheptulose-1,7-bisphosphatase (SBPase), thereby promoting carbon fixation and ribulose-1,5-bisphosphate (RuBP) regeneration under salt stress. Conversely, inhibition of endogenous MT synthesis by p-CPA exacerbated salt stress damage, further confirming MT’s crucial role in salt tolerance. These findings demonstrate that exogenous MT enhances salt tolerance in tomato seedlings by simultaneously improving photosynthetic electron transport efficiency and upregulating the activity and gene expression of key Calvin cycle enzymes, thereby promoting the coordination between light reactions and carbon fixation processes. This study provides valuable insights into the comprehensive regulatory role of MT in maintaining photosynthetic performance under saline conditions. 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

Although the NFT (nutrient film technique) solution application rate for cilantro is known for fresh water, the application rate is still debatable when using brackish water. The application rate alone influences flow velocity dynamics, which, when associated with nutrient solution salinity, can impact plant development when saline water is used. Knowledge of how to best combine solution salinity and application rates will help decide if brackish water can be used to produce cilantro under hydroponic conditions. Thus, two trials were conducted in sequence from November 2019 to February 2020 under a protected environment. Cilantro cv. Verdão was submitted to four levels of electrical conductivity of nutrient solutions (ECns of 1.7, 3.0, 4.5, and 6.0 dS m⁻¹) combined with four flow rates (1.0, 2.0, 3.0, and 4.0 L min⁻¹). Because Na⁺ and Ca²⁺ are predominant ions in brackish waters in the crystalline and sedimentary regions in the Brazilian Semiarid region, the first study used brackish waters dominated by NaCl and the second study used waters dominated by CaCl₂. We measured gas exchange and other photosynthetic parameters in plants cultivated with nutrient solutions high in Cl⁻ and prevalent in Na⁺ or Ca²⁺, each combined with different application rates. We concluded that the increment in salinity decreased the gas exchange of cilantro plants, especially when the brackish waters were dominant in Ca²⁺ and Cl⁻. Up to an ECns of 4.5 dS m⁻¹, plants maintained their leaf chlorophyll concentrations, although with reduced gas exchange. Salt stress compromised chlorophyll a fluorescence, affecting important parameters such as initial, maximum, and variable fluorescence. Besides the effects of salinity on chlorophyll a and b concentrations, the quantum and maximum yields of photosystem II remained stable, indicating that photosystem II may have adapted to the saline conditions applied in this study. The variation in application rates was unable to attenuate the deleterious effects of salinity, regardless of the ionic prevalence. We conclude that cilantro plants can be cultivated under hydroponic conditions, using currently accepted flow rates, with nutrient solutions of up to 3.0 dS m⁻¹ without severe damage to plant photosynthetic parameters. Full article

As a widely cultivated warm-season turfgrass, bermudagrass (Cynodon spp.) faces significant challenges in shaded environments due to its inherent low-light sensitivity. While improving photosynthetic adaptation represents a promising strategy to address this limitation, the associated regulatory mechanisms remain insufficiently characterized. In this study, we found that the overexpression of CdGLK1 significantly improved low-light tolerance in bermudagrass by increasing shoot weight, root weight, chlorophyll a, chlorophyll b, net photosynthetic rate (Pn), and maximum quantum yield of photosystem II (Fv/Fm). Furthermore, coordinated upregulation of both C₃ and C₄ pathway enzymes was observed under low-light stress, accompanied by enhanced antioxidant capacity and reduced photoxidative damage. Transcriptomic profiling further revealed CdGLK1-mediated activation of photosynthetic machinery components spanning light harvesting, electron transport, and carbon fixation modules. These findings establish CdGLK1 as a master integrator of photoprotection and metabolic adaptation under light-limiting conditions, providing both mechanistic insights and practical strategies for developing shade-resilient turfgrass cultivars. Full article

Nitrogen is a key element in promoting crop growth and development and improving photosynthesis. This study aimed to study the response of two rice genotypes to the restoration of N supply after varying periods of N deficiency. We used the low-nitrogen-tolerant rice Jijing 88 (JJ 88) and the nitrogen-sensitive rice variety Xinong 999 (XN 999) as test materials. The results of this study indicated that, compared to XN 999, JJ 88 has a higher content of the photosynthetic pigments. Photosynthesis in JJ 88 has strong adaptability under low-nitrogen conditions. Upon an increase in the nitrogen supply level, the maximum regeneration rate of ribulose biphosphate (RuBP, J_max) and the maximum carboxylation rate of RuBP (V_cmax) in JJ 88 showed a relatively large increase. The chlorophyll fluorescence parameters, including the effective quantum yield of photosystem II (Φ_PSII), the efficiency of excitation capture by open PSII centers (Fv′/Fm′), photochemical fluorescence quenching (qP), and the electron transfer rate (ETR) decreased slightly, while the non-photochemical fluorescence quenching (NPQ) increased slightly. Under low-nitrogen conditions, low-nitrogen-tolerant rice varieties maintain reasonable growth during the seedling stage. With an increase in the nitrogen supply level, the dry matter accumulation, photosynthetic pigment content, photosynthesis, and electron transfer ability of plants improve, but not to normal nitrogen supply levels. However, compared with XN 999, JJ 88 has a more proactive recovery ability. The research results provide valuable guidance for the breeding of nitrogen-efficient rice varieties and nitrogen fertilizer management. Full article

Background/Objectives: Globally, antibiotic contamination has become an emerging issue in agricultural lands. The presence of antibiotic residues in farmlands, especially through the application of manure fertilizers containing veterinary antibiotics, e.g., tetracycline (TC), can cause severe toxicity, which inhibits crop growth and performance, subsequently threatening human health via consumption of contaminated products. This study was conducted to evaluate the phytotoxicity of TC on Kimchi cabbage (Brassica campestris L.) during seed germination, seedling, and vegetative growth stages, along with its physiological responses and bioaccumulation under TC stress. Methods: The responses of cabbage plants to TC stress were assessed through a germination test and a pot experiment, conducted for three days and six weeks, respectively, under different doses of TC (0, 5, 10, 25, and 50 mg/L). Results: As a result of the germination test, higher TC doses (25 and 50 mg/L) tended to delay seed germination, but all treatments achieved a 100% germination percentage by Day 3 after sowing. Eight days after sowing, the length of shoots and roots of seedlings exhibited a TC dose-dependent decline, specifically under 50 mg TC/L, showing a considerable decrease of 24% and 77%, respectively, compared to control. Similar results were observed in the plants transitioning from the seedling to vegetative stages in the pot experiment. Four and six weeks after sowing, the 50 mg TC/L dose showed the strongest phytotoxicity in cabbage plants with physiological parameters, such as the maximum photosystem II quantum yield (F_v/F_m), pigment content (chlorophyll and carotenoid), biomass, and leaf number, significantly reduced by 26 to 60% compared to control. Interestingly, at lower TC doses (5 and 10 mg/L), a hormesis effect was observed in the phenotype and biomass of the plants. In addition, the degree of TC accumulation in the plants was highly dose-dependent at Week 4 and Week 6, but a temporal decline in TC accumulation was noted between these time points in all TC treatments. This phenomenon might affect the value of the bio-concentration factor (BCF) as an indicator of the plant’s tendency to uptake TC. That is, in Week 6, the dose-dependent reduction in BCF for TC in the plants was likely attributed to a dilution effect caused by plant biomass increase or a degradation mechanism within the plant. Conclusions: Overall, our findings suggest that tetracycline toxicity induces seed germination delay and influences seedling elongation and photosynthetic functions, ultimately impairing crop growth and performance. Also, the antibiotic dynamics related to accumulation and degradation in plants were identified. These results will not only suggest the toxicity threshold of TC for cabbage but also provide insights into effective soil management strategies for food production safety and agroecosystem sustainability in antibiotic-contaminated soils. Full article

Oil palm (Elaeis guineensis Jacq.) is the leading global oil-producing crop due to its high oil yield. Increasing global demands for palm oil require efficient propagation. Conventional breeding is practical but slow, making micropropagation an attractive alternative for rapidly multiplying superior genotypes. However, transitioning from in vitro to ex vitro conditions causes physiological stress, restricting survival and productivity. This study assessed gas exchange and chlorophyll fluorescence dynamics during acclimatization from in vitro conditions to field establishment, comparing the seedlings obtained in vitro with conventional seed-derived palm seedlings to conventional seed-derived palms. A pronounced photosynthetic efficiency decline occurred after transfer from in vitro culture, followed by a gradual recovery. The photosynthetic rate (A) increased from 0.86 µmol m⁻² s⁻¹ early in acclimatization to 15.43 µmol m⁻² s⁻¹ in field-established seedlings. Physiological characterization using CO₂ and light response curves identified the reductions in carboxylation efficiency and overall quantum yield CO₂. These biochemical constraints gradually diminished during acclimatization, facilitating a transition from heterotrophic to autotrophic growth. Chlorophyll fluorescence analysis revealed remarkable photoinhibition during initial ex vitro stages, indicated by a decreased maximum quantum efficiency of photosystem II. However, the seedlings progressively restored photochemical function throughout subsequent acclimatization phases. These findings highlight the importance of carefully regulating environmental parameters—particularly irradiance, humidity, and carbon availability—during early seedling acclimatization. The effective management of growth conditions significantly mitigates physiological stress, ensuring robust photosynthetic activity and optimized stomatal regulation. The improved acclimatization practices, therefore, can substantially enhance seedling survival rates, physiological resilience, and the overall field performance of micropropagated oil palms. Future research should focus on refining acclimatization protocols, emphasizing targeted physiological interventions to maximize the efficiency, commercial viability, and sustainability of oil palm clonal propagation. Full article