Plants

Urban trees are exposed to multiple co-occurring stressors, including heat, drought, and pollution driven by intensified urbanization and climate change. These environmental pressures can compromise tree vitality by disrupting photosynthetic performance and oxidative balance. In this study, we assessed the structural, physiological, and biochemical responses of three common urban tree species (Tilia platyphyllos, Celtis occidentalis, and Platanus × hispanica) growing under urban environmental conditions in Novi Sad, Serbia. Leaf traits were measured during June and August to capture seasonal stress variation. Structural indicators (SPAD, leaf thickness, leaf temperature differential), chlorophyll fluorescence traits (Φ_II, Φ_NPQ, F_v′/F_m′), oxidative stress biomarkers (TBARS, proline, GSH), and antioxidant enzyme activities (APX, CAT) were quantified. The Tree Health Risk Index (THRI) was calculated to integrate multilevel responses. Results revealed species-specific differences, with Tilia exhibiting the highest sensitivity, characterized by notable photochemical declines and oxidative stress under urban conditions. Celtis showed moderate resilience, while Platanus demonstrated the most robust performance and emerged as a promising candidate for climate-resilient urban sites. Heatmap clustering and trait contribution analyses confirm oxidative stress biomarkers and chlorophyll fluorescence traits as key indicators of urban stress. This study emphasizes the importance of integrating functional trait-based approaches for assessing tree health in urban greening.

The field experiment aimed to evaluate the effect of different nitrogen rates on accumulation of aboveground dry mass (AGDM), leaves area index (LAI), and intercepted photosynthetically active radiation (iPAR) of pea (Pisum sativum L.) varieties. The experiment was arranged in a factorial randomized block design consisting of three levels of the first factor (variety) and seven levels of the second factor (NPK fertilization treatments were used: (1) NPK 0:0:0 (control), (2) NPK 0:40:80, (3) NPK 15:40:80, (4) NPK 30:40:80, (5) NPK 45:40:80, (6) NPK 15 + 15:40:80, (7) NPK 60:40:80). The growth indicators (LAI and AGDM) and iPAR were assessed three times during the growing season. Nitrogen fertilization positively influenced LAI, but significant differences in LAI were found only under splitted N30 (N15 + N15), N45, and N60 applications, compared to the treatment N0 P40K80. In the dry 2015 and the optimal moisture 2016, N30, N45, and N60 rates significantly increased AGDM. The influence of fertilization on iPAR varied between experimental years, and it was strongest in the dry 2015, when applying N15+15 and N60 fertilization significantly increased iPAR, compared to the control. According to LAI and iPAR data, pea varieties were ranked in descending order: Simona, Ieva DS, and Respect. LAI significantly (p ≤ 0.01) correlated with AGDM and iPAR, but the relationship weakened as peas reached later growth stages. These results provide valuable knowledge, and it will be useful for researchers in developing new cultivation methodologies to achieve higher semi-leafless pea productivity by applying different combinations of nutrition and new varieties.

The root of Zanthoxylum nitidum is used in traditional Chinese medicine, whereas its leaves remain an under-exploited resource rich in essential oil (EO). By integrating cytological, analytical–chemical, and chemometric approaches, we have dissected the ontogeny of secretory cavities and the temporal accumulation of EO in Z. nitidum leaves for the first time. Cytological analyses revealed marginal-tooth-slit secretory cavities consisting solely of a spherical domain formed via a schizogenous mechanism. The EO yield followed a unimodal trajectory, peaking at growth stages ZN-2 and ZN-3. Gas chromatography–mass spectrometry (GC-MS) profiling identified 60 constituents; sesquiterpenoids reached maximal abundance at ZN-3, whereas monoterpenoids predominated at ZN-2. Second-derivative Fourier transform infrared spectroscopy (FTIR) spectra exhibited pronounced stage-specific differences, and hierarchical cluster analysis coupled with principal component analysis reliably discriminated developmental stages based on their chemical fingerprints. These findings provide a robust cytological and analytical framework for quality control and rational utilization of Z. nitidum leaves, laying the groundwork for their full medicinal exploitation.