Search Results (263)

Heat and high-irradiance stress increasingly threaten almond production in Mediterranean environments, where rising temperatures and prolonged summer droughts impair photosynthetic performance and yield. This study evaluated the effectiveness of three mineral-based shielding materials: kaolin, basalt powder, and zeolite. We hypothesized that the foliar application of reflective mineral materials would reduce leaf temperature, enhance photosynthetic efficiency, and improve yield without altering nut nutraceutical quality. A two-year field experiment (2024–2025) was conducted using a randomized block design with four materials (untreated control, kaolin, basalt powder, and zeolite). Physiological traits (gas exchange, chlorophyll fluorescence, leaf temperature, and SPAD index), morpho-biometric and biochemical parameters, and yield components were assessed. Kaolin and basalt powder significantly lowered leaf temperature (−1.6 to −1.8 °C), increased stomatal conductance and net photosynthesis, and improved photochemical efficiency (Fv′/Fm′) and electron transport rates. These treatments also enhanced drupe weight, kernel dry matter, and productive yield (up to +32% compared with the control). Zeolite produced positive but less prominent effects. No significant differences were detected in fatty acid profile, total polyphenols, or antioxidant capacity, indicating that the materials did not affect almond nutraceutical quality. Principal component analysis confirmed the strong association between kaolin and basalt powder and improved eco-physiological performance. Overall, mineral shielding materials, particularly kaolin and basalt powder, represent a promising, sustainable strategy for enhancing almond orchard resilience under Mediterranean climate change scenarios. Full article

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

Heat stress caused a stagnation in the growth and development of Passiflora edulis Sims. To investigate the effects of high-temperature stress, this study subjected P. edulis to 40 °C treatment for different durations; the changes in chlorophyll content, chlorophyll fluorescence parameters, photosynthetic parameters, transcriptome profiles, and photosynthesis-related genes of P. edulis under high-temperature stress were analyzed. The results showed that after 5 h of heat stress, the chlorophyll content of the leaves decreased by 31%, variable fluorescence/maximum fluorescence (Fv/Fm) decreased by 26.91%, photochemical performance index (PI_abs) by 99.28%, comprehensive performance index (PI_total) by 94.20%, light energy absorbed per unit area (ABS/CSm) by 13.56%, light energy captured per unit area (TRo/CSm) by 17.90% and quantum yield of electron transfer per unit area (ETo/CSm) by 92.61%. The net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (Gs) decreased by 47%, 41% and 38%, respectively, while intercellular CO₂ concentration (Ci) increased by 1.34 times. Transcriptome sequencing results of P. edulis under heat stress identified 2336 differentially expressed genes (DEGs), which were significantly enriched in pathways including chloroplast function and plant hormone signal transduction. GO enrichment analysis demonstrated that DEGs were significantly enriched in terms related to catalytic activity and chloroplast components. Concurrently, KEGG pathway analysis revealed that carbon fixation in photosynthetic organisms was among the key pathways showing significant enrichment of these DEGs. The expression levels of photosynthesis-related genes, including PePSAE, PeMADs, PebHLH, PeFAR1, PePSBS, PePnsB4, PebZIP and PeC2H2, exhibited a significant increase after 3 h of high-temperature stress and rapidly declined following 5 h. These findings lay a foundation for further research on the high-temperature stress response mechanism and photosynthetic regulation of heat tolerance in P. edulis. Full article

Climate change exacerbates soil moisture deficits, necessitating efficient water retention strategies. Superabsorbent polymers (SAPs) offer a potential solution to enhance water availability for crops during dry periods. Faba bean (Vicia faba L.) and pea (Pisum sativum L.) were selected as model legumes due to their high nutritional value, agricultural importance in temperate regions, and sensitivity to drought stress This study evaluated the effects of different SAP application rates on the yield and physiological performance of two legume species: faba bean (cv. Granit) and pea (cv. Batuta). The two-year (2017–2018) field experiments employed a randomized block design with four replicates. Treatments included three SAP doses: 0 (control, SAP0), 20 (SAP20) and 30 (SAP30) kg·ha⁻¹. The study was conducted over two years with contrasting weather: 2017 was wetter but had uneven rainfall distribution, while 2018 was drier and characterized by moisture deficits during critical growth stages. SAP application significantly increased seed yield in faba bean and pea, with the most favorable effect observed at 20 kg ha (average yield increase of 23.6% and 17.3%, respectively). SAP did not affect yield components in faba bean. However, in peas, an increase in pod number and seed number per plant was observed with the SAP30 dose compared to the SAP20 dose. Application of superabsorbent at a dose of 20 kg ha⁻¹ significantly increased photosynthesis rate in faba bean, the Fv/Fm index in the tested species, and the PI in peas compared to the control. However, the superabsorbent did not affect transpiration rate or the WUE coefficient in the tested legume species. Significantly higher yields in faba bean and pea and all tested plant structure parameters in pea were recorded in 2018 compared to 2017. The tested parameters of gas exchange and chlorophyll fluorescence were higher in pea in 2018 (except for transpiration intensity) and in faba bean in 2017. The findings suggest that SAPs can be a useful tool to mitigate water stress effects in legumes, although their effectiveness depends on environmental conditions. Therefore, SAP application may be a promising agronomic strategy in regions prone to irregular rainfall or moderate drought. Full article

Strawberry (Fragaria × ananassa (Weston) Rozier) is a high-value crop whose market success depends on fruit quality traits such as sweetness, firmness, and pigmentation. In sustainable agriculture, wood distillates are gaining interest as natural biostimulants. This study evaluated the effects of foliar application of two commercial wood distillates (WD1 and WD2) and one produced in a pilot plant at the Institute for Bioeconomy of the National Research Council of Italy (IBE-CNR) on strawberry physiology, fruit yield, and fruit quality under greenhouse conditions. Non-destructive ecophysiological measurements were integrated using optical sensors for proximal phenotyping, enabling continuous monitoring of plant physiology and fruit ripening. Leaf gas exchange and chlorophyll fluorescence were measured with a portable photosynthesis system, while vegetation indices and pigment-related parameters were obtained using spectroradiometric sensors and fluorescence devices. To assess the functional relevance of vegetation indices, a linear regression analysis was performed between net photosynthetic rate (A) and the Photochemical Reflectance Index (PRI), confirming a significant positive correlation and supporting PRI as a proxy for photosynthetic efficiency. All treatments improved photosynthetic efficiency during fruiting, with significant increases in net photosynthetic rate, quantum yield of photosystem II, and electron transport rate compared to control plants. IBE-CNR and WD2 enhanced fruit yield, while all treatments increased fruit soluble solids content. Non-invasive monitoring enabled real-time assessment of physiological responses and pigment accumulation, confirming the potential of wood distillates as biostimulants and the value of advanced sensing technologies for sustainable, data-driven crop management. Full article

While there is a consensus that the cytochrome b₆f complex (cytb₆f) in algae and plants is involved in the regulatory mechanism of oxygenic photosynthesis known as light-induced state transitions (STs), no such consensus exists for cyanobacteria. Here, we provide the first direct functional evidence for cytb₆f using single-point mutation data. We introduced a PetD-Phe124Ala substitution in the cyanobacterium Synechocystis sp. PCC 6803 to test the key predictions of the hydrophobic-mismatch (HMM) model for cytb₆f-driven STs in all oxygenic photosynthetic species. These predictions concern the role of the Phe/Tyr124^fg-loop-PetD and the extent and kinetic characteristics of STs. The effects of PetD-F124A mutation on STs were monitored using 77K and Pulse-Amplitude-Modulated (PAM) fluorescence. For comparison, we employed a phycobilisome (PBS)-less Synechocystis mutant and wild-type (WT) strain, as well as the stn7 mutant and WT of Arabidopsis plant. The PetD-F124A mutation reduced the extent of STs and selectively affected the two-exponential kinetics components of the transitions. Under State 1 conditions, the mutant exhibited ~60% less energetic decoupling of PBS from photosystem I (PSI) compared to the WT. It is explainable by the HMM model with the inability of the PetD-F124A mutant, during the induction phase of the State 2→State 1 transition to adopt the cytb₆f conformation with minimal hydrophobic thickness. PAM-derived parameters indicated that PSII electron transport function is not inhibited, and no detectable effect on cyclic electron transport around PSI was observed under low-light conditions. Circular dichroism and differential scanning calorimetry confirmed that both the PSI trimer/monomer ratio and the structural integrity of the PBSs are preserved in the mutant. The compensatory response to the mutation includes decreased PSI content and an increase in PBS rod size. In conclusion, (1) cytb₆f is involved in cyanobacterial STs; (2) evidence is provided supporting the HMM model; (3) the electron transfer and signal transduction functions of cytb₆f are separated into distinct domains; and (4) the signaling pathway regulating STs and pigment-protein composition in Synechocystis involves PetD-Phe124. Full article

Leaf photosynthesis plays an important role in maize growth and yield components due to its involvement in dry matter partitioning and organ formation. Nevertheless, how varying planting patterns affect maize leaf photosynthesis, chlorophyll fluorescence and subsequently maize yield remains poorly understood, particularly at various nitrogen rates. A two-season field experiment was performed on rainfed maize in 2021 and 2022 to explore the responses of photosynthetic physiological characteristics, leaf N and chlorophyll contents, chlorophyll fluorescence parameters, grain yield and water productivity to various planting patterns and N rates. The experiment included six planting patterns, i.e., flat planting without mulching (CK), flat planting with straw mulching (SM), ridge mulched with transparent film and furrow without mulching (RP1), flat planting with full transparent film mulching (FM1), ridge mulched with black film and furrow without mulching (RP2), and flat planting with full black film mulching (FM2). Additionally, there were two nitrogen rates, i.e., 0 kg N ha⁻¹ (N0) and 180 kg N ha⁻¹. The results showed that nitrogen application significantly improved leaf physiological characteristics. Under various planting patterns, leaf photosynthetic pigments, leaf area duration, leaf nitrogen content, QYmax and ΦPSII ranked as RP2 > RP1(FM2) > FM1 > SM(CK) in 2021, and RP2(RP1) > FM1(FM2) > SM(CK) in 2022. No significant variations were observed in water productivity (WP) among different film colors, with overall performance of RP2(FM2) > RP1(FM1) > SM > CK. WP significantly improved by 36.14% and 25.15% under N1 compared to N0 in 2021 and 2022, respectively. This pattern paralleled the fluctuation in water consumption intensity. Compared to CK, RP significantly increased leaf nitrogen content (29.3%), total Chl content (16.0%), QYmax (6.39%), ΦPSII (32.01%), and net photosynthesis rate (14.2%), thereby significantly improving grain yield (46.35%) and WP (27.69%), while reducing evapotranspiration (6.84%). Yield performance ranked as RP2 > (RP1 and FM2) > FM1 > SM > CK in 2021 and RP2 > RP1 > (FM1 and FM2) > SM > CK in 2022. Overall, RP2N1 obtained the highest principal component scores in both years, suggesting great potential to improve leaf photosynthetic physiological characteristics, thereby increasing grain production and ensuring food security in rainfed maize cultivation areas. Full article

Photosynthesis (PS) is the cornerstone of crop productivity, directly influencing yield potential. Photosynthesis remains an underexploited target in soybean breeding, partly because field-based photosynthetic traits are difficult to measure at scale. Also, it is unclear which reproductive stage(s) provide the most informative physiological signals for yield. Few studies have evaluated soybean PS in elite germplasm under field conditions, and the integration of chlorophyll fluorescence (CF) with UAV imaging for PS traits remains largely unexplored. This study evaluated genotypic variation in photosynthetic and canopy traits among elite soybean germplasm across environments and developmental stages using CF and UAV imaging. Linear mixed-model analysis revealed significant genotypic and G×E effects for yield, canopy and several photosynthetic parameters. Broad-sense heritability (H²) estimates indicated dynamic genetic control, ranging from 0.12 to 0.77 at the early stage (S1) and 0.20–0.81 at the mid-reproductive stage (S2). Phi2, SPAD and FvP/FmP exhibited the highest heritability, suggesting their potential as stable selection targets. Correlation analyses showed that while FvP/FmP and SPAD were modestly associated with yield at S1, stronger positive relationships with Phi2, PAR and FvP/FmP emerged during S2, underscoring the importance of sustained photosynthetic efficiency during pod formation. Principal component analysis identified photosynthetic efficiency and leaf structural traits as key axes of physiological variation. UAV-derived indices such as NDRE, MTCI, SARE, MExG and CIRE were significantly correlated with CF-based traits and yield, highlighting their utility as high-throughput proxies for canopy performance. These findings demonstrate the potential of integrating CF and UAV phenotyping to enhance physiological selection and yield improvement in soybean breeding. Full article

Phytochrome-interacting factors (PIFs) are key transcriptional regulators of phytochrome signalling that coordinate photomorphogenesis and photosynthesis under different environmental conditions. PIFs play an important role in this regulation and act mainly as negative regulators of photomorphogenesis, but under high-intensity light (HIL), their functions can also include adaptive roles. We investigated the contribution of individual PIFs to the adaptation of the photosynthetic apparatus in wild-type A. thaliana and pif4, pif5, pif4pif5, and pif1pif3pif4pif5 mutants exposed to HIL for 0, 16, 32, or 48 h. Chlorophyll fluorescence parameters (Y(II), F_v/F_m, NPQ), net photosynthesis (Pn), transpiration rates, stomatal conductance (g_S), pigment contents and the expression of key genes were evaluated. The response of plants to HIL varied depending on the duration of exposure. After 16 h of irradiation, the greatest reductions in Pn and g_S were observed in the pif4pif5 and pif1pif3pif4pif5 mutants, whereas after 48 h, the decreases were most pronounced in the pif4, pif5, and pif4pif5 mutants. After 16 h of HIL exposure, the absence of pif4 and pif5 did not substantially alter the chlorophyll fluorescence parameters. However, after 48 h, both Y(II) and Fv/Fm were lower in these mutants than in the wild type, indicating changes in PSII functional status rather than direct reductions in photochemical quantum efficiency. At 16 h, chlorophyll levels were the highest in pif5 and WT, whereas anthocyanin and UV-absorbing pigment (UAP) levels were the highest in pif4, pif5 and WT. After 48 h, the highest levels of any pigments were detected in the WT and the pif1pif3pif4pif5 mutant. These results suggest that the accumulation of anthocyanins and UAPs under HIL is likely associated with the regulation of transcription factors, such as PIFs, de-etiolated 1 (DET1), constitutive photomorphogenic 1 (COP1), and elongated hypocotyl 5 (HY5). During prolonged HIL exposure, the absence of PIF4 and PIF5 has a critical impact on photosynthesis and the accumulation of photosynthetic pigments, whereas the simultaneous loss of PIF1, PIF3, PIF4, and PIF5 is less detrimental. This finding likely indicates opposite roles of PIF1 and PIF3 in the above-described processes, on the one hand, and PIF4 and PIF5, on the other hand, under HIL conditions. Full article

Photosynthesis is a primary plant physiological process, which can easily be affected by various environmental factors, including biotic stressors. The exogenous application of different substances like plant growth regulators might benefit this process both under normal and stress conditions. It is well known that the polyamine spermine positively modulates photosynthesis. We evaluated the effects of 5 mM spermine seed priming on photosynthesis-related parameters in wheat (Triticum aestivum L.) plants grown from Fusarium culmorum-infected seeds. Under no stress conditions, the spermine seed priming improved leaf gas exchange, chlorophyll a fluorescence, and leaf pigment content compared to the control. In non-primed seedlings exposed to the pathogen, these parameters were significantly affected. The most substantial reductions were seen in the net photosynthetic rate (56%), transpiration rate (63%), and stomatal conductance (58%). In plants cultivated from seeds primed with spermine the pathogen’s adverse effect on the assessed parameters was mitigated. Our study demonstrates the efficacy of spermine seed priming in sustaining photosynthetic activity in wheat plants exposed to biotic stress induced by Fusarium culmorum. Full article

Avocado trees (Persea americana Mill.) grown in Mediterranean conditions are exposed to high temperatures and intense solar radiation during summer, factors that can severely compromise plant water status and key physiological processes. To minimize these stressful conditions, the use of shade nets is an agronomical technique that permits the creation of an optimal microclimate for crop development. Thus, the aim was to evaluate the effects of shade netting on the physiological response of young avocado trees commercially grown under Mediterranean climatic conditions. The main results showed similar circadian rhythms of plant water status under both crop systems (open-air and shaded) in both seasons. However, the use of shading nets altered the circadian rhythm of leaf gas exchange. In summer, stomatal conductance (g_s) remained significantly more open after midday in shaded trees, allowing higher leaf transpiration (E_leaf) and cooler leaf temperature (T_leaf). A similar daily pattern was observed in chlorophyll a fluorescence parameters, including the effective quantum yield of photosystem II (ΦPSII) and the electron transport rate (ETR), with the lowest values occurring at midday. In shaded plants, ΦPSII and ETR remained higher after midday than in open-air, suggesting a lower photochemical inhibition of photosynthesis caused by heat stress and photoinhibition. Thus, the use of shade nets represents an agronomic alternative technique for cultivating avocados in Mediterranean climate conditions. Full article

Cacti of the genera Opuntia and Nopalea exhibit morphophysiological and biochemical characteristics that favor their adaptation to semiarid environments, such as crassulacean acid metabolism (CAM) and cladode succulence. These strategies reduce water loss and allow the maintenance of photosynthesis under stress conditions. In this study, we evaluated the seasonal variation in the physiological and photochemical responses of forage cactus clones grown in semiarid environments, considering the rainy, dry, and transition seasons. The net photosynthetic rate (P_n) and chlorophyll fluorescence parameters varied significantly as a function of water availability and microclimatic conditions. We found higher CO₂ assimilation rates during the rainy season, while the dry season resulted in a strong impairment of photosynthetic activity, with reductions of 65% in stomatal conductance, 37% in transpiration, 20% in maximum quantum efficiency of photosystem II, and 19% in the electron transport rate. Furthermore, during these periods, we observed an increase in initial fluorescence and non-photochemical dissipation, demonstrating the activation of photoprotective mechanisms against excess light energy. During the transition seasons, the cacti exhibited rapid adjustments in gas exchange and energy dissipation, indicating the adaptive plasticity of CAM pathway. The MIU (Nopalea cochenillifera (L.) Salm-Dyck), OEM (Opuntia stricta (Haw.) Haw.), and IPA (Nopalea cochenillifera (L.) Salm-Dyck) clones demonstrated greater resilience, maintaining greater stability in P_n, instantaneous water use efficiency, and photochemical parameters during the drought. In contrast, the OEA (Opuntia undulata Griffiths) clone showed high sensitivity to water and heat stress, with marked reductions in physiological and photochemical performance. In summary, the photosynthetic efficiency and chlorophyll fluorescence of CAM plants result from the interaction between water availability, air temperature, radiation, and genotypic traits. This study provides a new scientific basis for exploring the effects of environmental conditions on the carbon and biochemical metabolism of cacti grown in a semiarid environment. Full article

One way to counteract the effects of environmental stresses, including drought, is to use products with growth-promoting properties for plants. Such agents include quercetin, which is known for its antioxidant and photosynthesis-enhancing properties. In the conducted experiment, the influence of the quercetin–copper complex (Q-Cu (II)) treatment, characterized by strong high solubility in water and strong antioxidant properties, was investigated. The pot experiment demonstrated the effect of spraying with Q-Cu (II) solutions (0.01, 0.05 and 0.1%) on wheat plants growing under drought stress conditions. Two treatments of Q-Cu (II) solutions were applied, and chlorophyll content and chlorophyll fluorescence (the maximum quantum yield of photosystem II (PSII) photochemistry (F_v/F_m), the efficiency of the water-splitting complex on the donor side of PSII (F_v/F_o), and the photosynthetic efficiency index (PI)), as well as gas exchange (photosynthetic network intensity (P_N), transpiration rate (E), stomatal conductance (g_s) and intercellular CO₂ concentration (C_i)), were measured 1 and 7 days after each treatment. In addition, antioxidant enzyme activity (catalase (CAT), peroxidase (SOD) and guaiacol peroxidase (GPOX)) and reactive oxygen species (ROS) levels were determined. Drought stress caused a decrease in chlorophyll content, and values of parameters F_v/F_m, F_v/F_o, PI and P_N, E, g_s, C_i, as well as an increase in ROS levels and antioxidant enzyme activity. Exogenous Q-Cu (II) improved photosynthetic indices and modulated redox status in a dose-dependent manner: 0.01–0.05% reduced ROS, whereas 0.1% increased ROS while concomitantly enhancing antioxidant enzyme activities and photosynthetic performance, consistent with ROS-mediated priming. The conducted research indicates the possibility of using Q-Cu (II) as a product to enhance the efficiency of the photosynthetic process under drought stress. Full article

Adventitious rooting is a key step for the clonal propagation of many economically important horticultural and woody species. Accumulating evidence suggests that nitric oxide (NO) serves as a key signaling molecule with key roles in root organogenesis. However, the role of NO in adventitious root development and its underlying mechanism in sweetpotato cuttings remain to be clarified. In this study, a pot experiment was conducted using hydroponically cultured sweetpotato cuttings (Ipomoea batatas cv. ‘Jin Ganshu No. 9’) treated with different concentrations of sodium nitroprusside (SNP, an NO donor) solution (0, 10, 50, 100, 200, and 500 μmol·L⁻¹). Three treatments were established: Control, SNP (the optimal concentration of SNP), and SNP + 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO, an NO scavenger). The results showed that NO promoted adventitious rooting in a dose-dependent manner, with the maximal biological response observed at 100 μM SNP. At this concentration, the root number and length of adventitious roots increased by 1.22 and 2.36 times, respectively, compared to the control. SNP treatment increased fresh root weight, dry root weight, the content of soluble sugar, soluble protein, chlorophyll a (Chl a), chlorophyll b (Chl b), and total chlorophyll (a + b) [Chl(a + b)], as well as the activities of peroxidase (POD), polyphenol oxidase (PPO), and indole acetic acid oxidase (IAAO). It also enhanced the levels of maximum fluorescence (Fm), maximum photochemical efficiency of photosystem II (Fv/Fm), absorbed light energy (ABS/RC), trapped energy flux (TRo/RC), and electron transport flux (ETo/RC), while decreasing starch content and initial fluorescence (Fo). On the 7th day, the SNP treatment significantly enhanced several biochemical parameters compared to the control. We observed an increase in many of the parameters: POD activity by 1.35 times, PPO activity by 0.55 times, chlorophyll content (Chl a by 0.66 times, Chl b by 0.22 times, and Chl a + b by 0.57 times), and photosynthesis parameters by 28–98%. Meanwhile, starch content and Fo in the SNP treatment decreased by 10.77% and 23.86%, respectively, compared to the control. Furthermore, the positive effects of NO on adventitious root development and associated biochemical parameters were reversed by the NO scavenger cPTIO. Additionally, significant and positive correlations were observed between morphological characteristics and most physiological indicators. Collectively, these results demonstrate that NO promotes adventitious root formation, which may be by enhancing rooting-related enzyme activities, improving photosynthetic performance in leaves, and accelerating the metabolism of soluble sugar, soluble protein, and starch. Full article

The overuse of pesticides has raised serious food-safety and environmental concerns. Carbon dots (CDs) can act as biostimulants by enhancing photosynthesis, thereby promoting plant growth and stress tolerance. However, their roles in plant pesticide detoxification remain unclear. This study synthesized nitrogen-doped carbon dots (N-CDs) with strong blue fluorescence, excellent biocompatibility, and no cytotoxicity observed in HEK 293T cells. The N-CDs were synthesized from 1.025 g citric acid and 0.379 g urea, producing particles with a size of around 2.42 nm and abundant hydrophilic groups. When applied to tomato plants, N-CDs (especially at 150 mg·L⁻¹) significantly reduced chlorothalonil (CHT) residues affecting tomato, by up to 66%. Importantly, N-CDs also improved tomato plant growth, reversing the negative effects of CHT on key parameters such as height, leaf area, and biomass. Indeed, under CHT conditions, N-CDs significantly reduced the contents of malondialdehyde, superoxide, and hydrogen peroxide. In contrast, N-CDs significantly increased the activities of superoxide dismutase, peroxidases, catalase, and ascorbate peroxidase to 117.57%, 158.53%, 162.79%, and 152.23%, respectively. Notably, N-CDs dramatically changed the glutathione pool for tomato detoxification. Overall, this study synthesized the non-cytotoxic N-CDs that not only promote tomato growth but also alleviate CHT toxicity by strengthening the tomato’s antioxidant defense system. Full article