This study adopted a two-factor （cultivar and waterlogging） completely randomized design to elucidate the responses of poplar trees to waterlogging stress. One-year-old seedlings of five main poplar cultivars-Populus deltoides ‘Xianglin 90’（XL90），P. deltoides ‘Jianghuai No.1’（JH1），P. deltoides ‘Wanlin No.1’（WL1），P. deltoides ‘Zhonghe 1’（2025），and P. deltoides ‘Nanyang 1’（Juba）-were subjected to three treatments：normal irrigation（CK），shallow waterlogging（DSY），and deep waterlogging（GSY）. Growth indices and chlorophyll fluorescence parameters were systematically measured，and the carbon（C），nitrogen（N），and phosphorus（P） contents as well as their stoichiometric ratios in leaves，stems，and roots were analyzed. The results showed that waterlogging stress significantly reduced the survival rate of all cultivars and inhibited the growth of tree height and basal diameter. Significant differences in waterlogging tolerance were observed among the cultivars：XL90 exhibited a relatively higher survival rate（67%） and better growth performance under GSY；Juba showed the highest survival rate（83%） under DSY but was sensitive to GSY；JH1，WL1，and 2025 experienced severe growth inhibition under both waterlogging treatments，and their mean growth parameters under DSY might be biased by individual variation due to low survival rates. Chlorophyll fluorescence analysis showed that the GSY treatment significantly decreased the actual photochemical efficiency（Φ_PSⅡ） and photochemical quenching coefficient（q_P） in all cultivars，whereas q_P under DSY did not decrease significantly compared with CK. Waterlogging stress significantly altered the C，N，and P contents in various organs，manifested by increased leaf C content，decreased leaf N content（except for WL1），and increased N content in stems and roots. Except for JH1，the P content in roots showed an increasing trend. Stoichiometric analysis indicated that for most cultivars，leaf C∶N and N∶P ratios were changed significantly with increasing waterlogging intensity，while the response of C∶P exhibited clearly cultivar-specific difference. Comprehensive evaluation indicated that the waterlogging tolerance of the five poplar cultivars was ranked as XL90>Juba>2025>JH1>WL1. This study elucidated the mechanisms underlying cultivar differences in responding to waterlogging stress from the perspectives of photosynthetic physiology and ecological stoichiometry.

Fluoroquinolone antibiotics（FQs） are widely detected in agricultural irrigation water，livestock wastewater，and coastal wetlands，posing potential stress to plant growth and ecological processes. Taking ofloxacin（OFX） and enrofloxacin（ENR） as representative compounds，this study employed physiological and biochemical assays in combination with transcriptomic analysis to systematically elucidate the physiological responses and molecular regulatory mechanisms of Suaeda salsa under FQs stress. The results showed that both OFX and ENR induced significant oxidative stress in both the aboveground and belowground parts of S. salsa. Comparatively，ENR caused more pronounced lipid peroxidation，which was accompanied by the significant differential expression of genes related to phenylpropanoid metabolism and ABC（ATP-binding cassette） transporters. In contrast，OFX stress primarily impaired photosystem structure and function，while simultaneously enhancing antioxidant defense through the regulation of the WRKY transcription factor family and MAPK（mitogen-activated protein kinase） signaling pathways. Furthermore，both antibiotic treatments promoted the glycolysis-pyruvate metabolism pathway，thereby providing sustained energy supply and reducing power to support stress resistance. Collectively，under FQs stress，S. salsa exhibited a multi-level adaptive response strategy driven by the coordinated regulation of structural defense，metabolic reprogramming，and signaling pathways.

To systematically elucidate the growth response characteristics of pigeon pea（Cajanus cajan）seedlings under different concentrations of salt stress and the dynamic changes in antioxidant enzyme activities and flavonoid metabolite accumulation，uniformly grown pigeon pea seedlings were used as plant materials. The seedlings were treated with 0，50，100，150，and 200 mmol⋅L^-1 NaCl solution. Phenotypic observation and root scanning analysis were conducted at 1，3，5，and 7 days after treatment. Root morphological parameters，including root length，surface area，projected area，volume，and average diameter，were measured. Meanwhile，the activities of superoxide dismutase（SOD） and peroxidase（POD） were determined. In addition，samples collected under 150 mmol⋅L^-1 NaCl treatment at different time points were analyzed using UPLC-MS/MS for qualitative and quantitative profiling of flavonoid metabolites，combined with analysis of related gene expression changes. Results showed that salt stress significantly inhibited the growth of pigeon pea seedlings in a concentration-dependent manner. With increasing salt concentration and prolonged treatment duration，seedlings exhibited inhibited primary root elongation，restricted lateral root development，and reduced shoot growth，with the inhibitory effect becoming more pronounced after 3 days of treatment. Root morphological parameters generally increased over time；however，the magnitude of increase was significantly reduced under 100 mmol⋅L^-1 and higher NaCl treatments，whereas 50 mmol⋅L^-1 NaCl showed a promoting effect on root growth at certain time points. The average root diameter showed relatively small variation under 50 mmol⋅L^-1 NaCl treatment but slight increase under moderate to high salt conditions. SOD activity increased significantly under moderate salt concentration and then stabilized，while POD activity continuously increased with increasing salt concentration and treatment duration. Under 150 mmol⋅L^-1 NaCl treatment，flavonoid metabolites in roots exhibited stage-dependent accumulation patterns. Root stilbene acid mass concentration showed an overall increasing trend，isovitexin mass concentration fluctuated markedly，genistin displayed induced accumulation，and genistein mass concentration significantly increased at later stages of treatment. Gene expression analysis showed that the expression levels of CcPAL2，Cc4CL4，and CcCHS3 were downregulated，while CcC4H1 was significantly upregulated，and CcCHI2 and CcIFS1 were also induced. In conclusion，salt stress inhibited the growth of pigeon pea seedlings and showed clear time- and concentration-dependent effects. Antioxidant enzyme activities and flavonoid metabolite levels dynamically changed during the stress process，and the key genes in the flavonoid biosynthesis pathway exhibited differential regulation under salt stress conditions.

Chlorogenic acid（CGA） plays an important role in regulating plant disease resistance. Under pathogen stress，plants typically accumulate various secondary metabolites that are closely associated with stress tolerance. Among these，CGA can enhance plant disease resistance by modulating secondary metabolism；however，the underlying mechanisms remain poorly understood. To further elucidate these mechanisms，Scutellaria baicalensis plants treated with exogenous CGA were subjected to pathogen infection. Leaf chlorophyll content，malondialdehyde（MDA） content，lesion area，and flavonoid content were determined，and transcriptome sequencing coupled with cis-acting element analysis of enzyme-coding genes were performed.The results showed that CGA significantly enhanced the resistance of S. baicalensis to leaf spot disease and influenced the accumulation of the flavonoids naringenin and apigenin. Compared with the control，CGA-treated plants exhibited smaller lesion area，higher chlorophyll level，and lower MDA content. Transcriptome analysis of CGA-treated samples identified 563 differentially expressed genes（DEGs），which were mainly enriched in pathways including phenylpropanoid biosynthesis，starch and sucrose metabolism，linoleic acid metabolism，galactose metabolism，and flavonoid biosynthesis. Notably，key flavonoid biosynthetic enzyme genes-SbPAL，SbC4H，Sb4CL1，Sb4CL2，SbFNS，SbHCT1，and SbHCT2-were significantly upregulated. Cis-acting element analysis further revealed that the promoter regions of these genes were enriched in binding sites for transcription factors such as bHLH，MYB，and GRF.In conclusion，this study demonstrates that exogenous CGA likely enhances the resistance of S. baicalensis to leaf spot disease by promoting the expression of key genes in the flavonoid biosynthesis pathway，thereby increasing flavonoid accumulation.

To investigate the response patterns to nitrogen forms and determine the optimal nitrogen supply form for enhancing drought tolerance，seedling morphology，biomass，needle water status，and osmoprotectant mass fraction were examined in two-year-old P.koraiensis seedlings under drought levels（moderate and severe drought，with full irrigation as the control） and nitrogen forms（nitrate nitrogen，ammonium nitrogen，and glycinate nitrogen，with no nitrogen application as the control）. The results indicated that the interaction between drought levels and nitrogen forms significantly affected the root morphology，root and needle biomass，seedling quality，needle water status，and osmoprotectants in P.koraiensis seedlings（P<0.05）. Under full irrigation，seedlings fertilized with ammonium nitrogen exhibited significantly superior performances in seedling height，total root length，total root area，root biomass，Dickson’s quality index，and osmoprotectant mass fraction compared to those fertilized with glycinate nitrogen（P<0.05）. Under moderate drought，seedlings fertilized with glycinate nitrogen showed no significant differences in seedling height，root collar diameter，total root volume，root tip number，biomass in various organs and the whole plant，Dickson’s quality index，needle water status，and proline mass fraction compared to those fertilized with ammonium nitrogen. Under severe drought，seedlings fertilized with glycinate nitrogen demonstrated significantly better performances in root collar diameter growth，total root length，total root area，root biomass，needle biomass，total biomass，Dickson’s quality index，needle water status，and needle osmoprotectant mass fraction compared to those fertilized with inorganic nitrogen（P<0.05）. The response of P. koraiensis seedlings to nitrogen forms was significantly affected by drought levels. Under full irrigation，inorganic nitrogen（especially ammonium nitrogen） favored seedling growth and osmoprotectant accumulations. However，under severe drought，glycinate nitrogen improved seedling water status by promoting osmoprotectant accumulations，being more beneficial for seedling growth than inorganic nitrogen. This study elucidates the growth response of P. koraiensis seedlings to different nitrogen forms under drought stress，providing theoretical basis and technical reference for cultivating drought tolerant seedlings through nitrogen application in nurseries.

The basal petal blotch of Paeonia rockii is the primary genetic source of blotch traits in cultivated tree peonies. To clarify the timing of blotch initiation，its expansion pattern，and the relationship between blotch development and pigment accumulation，basal blotch formation at seven developmental stages were systematically examined in ten P.rockii cultivars. At stage S2，single pigmented cells first appeared and gradually developed into pigment cell clusters，consisting of a deeply pigmented central cell surrounded by lightly pigmented peripheral cells. Blotch expansion occurred through the proliferation and enlargement of these pigment cell clusters. The blotch outline was initially established at stage S3，preceding the visible coloration of the petal background，and a second peak of pigment cell proliferation was observed at stages S6-S7. During S2-S3，significant decreases in L* and b* values and an increase in a* value were recorded in the blotch region. Anthocyanins were detectable in the blotch as early as S2，with cyanidin-3，5-di-O-glucoside（Cy3G5G） and peonidin-3，5-di-O-glucoside（Pn3G5G） as the predominant components. Linear regression analysis indicated that Pn3G5G had strong explanatory power for changes in L*，a*，and b* values and was the key anthocyanin contributing to the formation of purple-red blotches. Pelargonidin-3，5-di-O-glucoside（Pg3G5G） may be involved in the formation of black blotches. In summary，blotch formation in P. rockii is a dynamic developmental process characterized structurally by the expansion of pigment cell clusters and biochemically by the spatiotemporally specific accumulation of anthocyanins.