Introduction: Paris polyphylla var. chinensis (Franch.) Hara (P. polyphylla) is a perennial medicinal plant with a reputation for therapeutic properties. It is imperative to study the photochemical processes of P. polyphylla in order to determine the optimal levels of shading and moisture management for its cultivation in artificial environments.Methods: In this study, six shading levels (no shading, 30%, 50%, 70%, 80% and 90% shading) and three soil water contents (20%, 40% and 60% of the soil water saturation capacity) were established to determine the appropriate shade intensity and soil moisture content for the growth of P. polyphylla.Results: The results showed that only the low shade groups (no shade and 30% shade) showed irreversible damage to the daily photosynthetic dynamics of the plant over the course of a day. It is important to note that excessive light can damage not only the quantum yield for electron transport (φDo) and PSII light quantum yield (Fv/Fm), but also various physiological mechanisms that can lead to overall plant damage and a decline in organic matter. A comparison of Fv/Fm during the midday period showed that the optimum shade intensity is between 50% and 70%. Low shading can significantly increase light use efficiency (LUE), but also reduces net photosynthetic rate (Pn) and transpiration (Tr), indicating the negative effect on P. polyphylla growth. Considering the balance between growth rate and damage incidence, 50% shade should be the optimal treatment for P. polyphylla, followed by 30% and 70% shade. It was also observed that treatment with low soil water content (20%) significantly reduced Pn and LUE, while increasing stomatal conductance (gs) and water use efficiency (WUE). This is associated with a decrease in the light response curve, indicating that low soil moisture inhibits the growth of P. polyphylla and increases the likelihood of irreversible light damage, so the optimum soil moisture content for P. polyphylla should be above 20%.Discussion: Considering the economic benefits and the growth and health of P. polyphylla in artificial cultivation, it is recommended that shade be controlled at around 50% while maintaining soil moisture between 40% and 60% of water content.

Ammonium nitrogen (NH₄⁺-N) and nitrate nitrogen (NO₃⁻-N) that can be absorbed and utilized by plants are heterogeneously distributed in soil, which affects plant growth and bacterial communities in the roots. To investigate the effects of single and mixed nitrogen (N) on bacterial communities in the rhizospheres and root surfaces of Cunninghamia lanceolata (CR, CRS) and Schima superba (SR, SRS), we subjected three different ratios of NH₄⁺-N to NO₃⁻-N 2:0, 1:1 (control, CK), 0:2 to cultivate the seedlings. Compared with the CK, the ratio of 0:2 increased the number, diversity, and composition of bacteria in CR, whereas the ratios of 2:0 and 0:2 both decreased in CRS, SR, and SRS. The bacterial diversities were both R > RS in two tree species, but there was no discernible trend between the two tree species in the rhizosphere and root surface. Proteobacteria and Bacteroidota were the dominant bacterial phyla in CR and CRS, whereas Proteobacteria and Acidobacteriota dominated in SR and SRS. Patescibacteria and Planctomycetota promoted the aboveground growth of C. lanceolata but negatively drove root growth. Patescibacteria and Cyanobacteria in SR were related to its root growth, whereas the Actinobacteriota in SR and SRS, and the Patescibacteria and Cyanobacteria in SRS, promoted its aboveground growth. Overall, the mixed N addition was more conducive to bacterial community proliferation than single N on rhizospheres compared to root surfaces. The opposite reactions were observed from the aboveground and underground growth, which were driven by a few dominant bacterial phyla.

Introduction: Frequency and intensity of “hot droughts” are escalating globally, yet the physiological mechanisms governing tree resilience to the synergistic impacts of water deficiency and heatwaves remain poorly understood. Methods: Here, we investigated the dynamics of carbon (C), nitrogen (N), and non-structural carbohydrates (NSC) in leaves, stems, and roots of three subtropical tree seedlings ( Schima superba , Cyclobalanopsis glauca , and Phoebe bournei ) during combined stress and subsequent rehydration. Results: Our results demonstrate that combined stress triggers a “dual-deficit” mechanism—simultaneous cessation of carbon assimilation and accelerated respiratory consumption, as inferred from the significant depletion of organ-specific NSC pools—that exerts a more profound impact on NSC pools than on C-N stoichiometry. Structural equation modeling revealed a spatiotemporal division of labor where seedlings prioritize acute hydraulic safety by sacrificing foliar metabolic performance, incurring a delayed “metabolic debt” in roots that manifests as significant legacy effects during recovery. Discussion: Crucially, the three species exhibited divergent strategies to manage this metabolic capital: S. superba displayed high resilience through “physiological re-priming,” rapidly restoring foliar source capacity; C. glauca adopted a “conservative buffering” strategy, sequestering NSC in stems to bridge the gap between resistance and hydraulic recovery; conversely, P. bournei suffered from a maladaptive “root-leaf decoupling,” where structural rigidity in roots impeded the remobilization of reserves, leading to systemic NSC depletion indicative of potential carbon starvation. These findings underscore that resilience to compound climate extremes depends not merely on static resistance traits, but on the flexibility of inter-organ coordination to resolve the metabolic debts of recovery.

Phytoncides are major bioactive compounds in biogenic volatile organic compounds (BVOCs) from landscape plants and benefit human health. However, interspecific differences in phytoncides and their associations with leaf functional traits remain unclear. We analyzed BVOCs from eight landscape trees using dynamic headspace adsorption and gas chromatography-mass spectrometry (GC-MS). Results showed that a total of 32 BVOCs were identified at the same site and during the same season. Eucalyptus robusta (E. robusta) exhibited the highest phytoncide content, with gamma-terpinene, DL-limonene, and 3-carene. Ficus religiosa (F. religiosa) showed the highest isoprene. Schima superba (S. superba) was rich in alpha-pinene and beta-pinene, and Cunninghamia lanceolata (C. lanceolata) was dominated by alpha-terpinene. Lagerstroemia indica (L. indica) displayed the largest leaf length (LL), leaf area (LA), leaf dry weight (LDW), and specific leaf weight (SLW). F. religiosa had the greatest leaf width (LW) and leaf fresh weight (LFW). C. lanceolata and E. robusta had the smallest leaf traits. Correlations showed that LA was positively correlated with isoprene and five monoterpenes in S. superba. SLW was positively correlated with isoprene and three monoterpenes in F. religiosa, and leaf temperature (LT) was negatively correlated with isoprene and four monoterpenes in E. robusta. PCA revealed covariation and opposing trends between leaf traits and phytoncides. This study suggests that E. robusta, C. lanceolata, F. religiosa and S. superba are potential tree species of high-phytoncide content for scientific and rational planting of landscape forests.