Background and AimsGlobal climate change is intensifying the co-occurrence of abiotic stresses, particularly combined waterlogging/submergence and salinity, posing severe and escalating threats to woody plant ecosystems critical for biodiversity, carbon storage, and soil stabilization. Despite extensive research on herbaceous species, understanding of woody plant responses remains fragmented and disproportionately focused on specific groups like mangroves and halophytes. This review aims to synthesize and critically evaluate the current state of knowledge on the integrated physiological, morphological, and molecular responses of diverse woody plants to this challenging combined stress scenario.MethodsA comprehensive synthesis and analysis of existing scientific literature was conducted. This involved systematically examining empirical studies, comparative analyses, and theoretical frameworks related to the responses of various woody plant species to the concurrent application of waterlogging/submergence and salinity stress, drawing comparisons to single-stress effects and herbaceous model systems.ResultsThe majority of woody plants exhibit synergistic, more detrimental effects under combined stress compared to either stress alone. Key manifestations include significantly heightened inhibition of photosynthesis, severe disruption of ion (particularly Na+ and Cl-) homeostasis leading to toxicity, and exacerbated oxidative damage. Woody plants utilize core stress tolerance mechanisms analogous to herbaceous species, such as ion exclusion/compartmentalization, activation of enzymatic and non-enzymatic antioxidant systems, and osmotic adjustment via compatible solute accumulation. Crucially, they also deploy distinctive structural and long-term adaptive strategies, including the development of specialized organs (pneumatophores, hypertrophic lenticels), deep root systems for accessing less saline groundwater, and physiological acclimation processes leveraging their perennial nature. Nevertheless, critical knowledge gaps persist, particularly concerning the underlying molecular signaling networks, the mechanisms of long-term adaptation over years/decades, and the specific responses of mature trees in natural ecosystems.ConclusionSignificant gaps hinder a comprehensive understanding of how woody plants cope with combined waterlogging/submergence and salinity stress. To advance fundamental knowledge and inform effective ecological restoration strategies for climate-resilient landscapes, future research must prioritize the application of integrated multi-omics approaches (genomics, transcriptomics, proteomics, metabolomics), the development of high-efficiency genetic transformation techniques for recalcitrant woody species, the deployment of advanced high-throughput phenotyping platforms, and crucially, long-term field-based studies simulating realistic future stress scenarios.

Environmental stresses, particularly drought and salinity, significantly impair plant growth and productivity. This study explores the novel synergistic interaction between biochar and arbuscular mycorrhizal fungi (AMF) in enhancing the resilience of sweet pepper plants subjected to the individual or combined stresses of drought and salinity. The impact of these biostimulants on growth parameters, photosynthetic efficiency, and biochemical traits was assessed. Sweet pepper plants were subjected to drought stress (35 and 75% of field capacity (FC)), salinity (0 and 150 mM NaCl), and their combined effects (150 mM NaCl +35% of FC), with treatments including biochar (2.5 g/kg soil), AMF, and their combination. Under drought stress, the dual application of biochar and AMF notably improved plant growth indicators such as shoot fresh weight, shoot height, and number of leaves by 50, 14, and 3%, respectively compared to the control plants. Under drought and salinity combined, this combination also enhanced photosynthetic pigments content by 144% for Chl a, 316% for Chl b, 212% for Chl T and 302% for carotenoids content respectively compared to the control plants. Additionally, AMF and Biochar combined reduced the oxidative effect of malondialdehyde (MDA) by 37% and hydrogen peroxide (H2O2) by 43%, indicating a reduction in oxidative damage. Furthermore, a significant increase in antioxidant enzyme activities was observed, with peroxidase activity (POX) rising by 33% and polyphenol oxidase activity (PPO) increasing by 212%, indicating enhanced stress tolerance. This study underscores the efficacy of using biochar and AMF together to bolster sweet pepper plant resilience, offering a viable strategy for improving plant performance under challenging environmental conditions.

To protect agro-systems and food security, study on the effect of microplastics and heavy metals on edible plants is of great significance. Existing studies mostly used virgin microplastics to evaluate their effects on plants, effects of naturally aged microplastics and their combined effects with heavy metals are rarely explored. In this study, single and combined effect of polyethylene microplastics (PE, both virgin and naturally aged) and cadmium (Cd) on pakchoi under seedling and mature stages were analyzed from perspectives of growth inhibition, oxidative damage, nutrition content and soil enzyme activities. Results showed that inhibiting effects of naturally aged PE (PEa) on the growth of pakchoi were stronger than virgin PE (PEv), whereas co-contamination of PEa and Cd was less toxic than that of PEv and Cd. The co-contamination of PE and Cd could inhibit pakchoi dry biomass by over 85 %. Both single and combined contamination of PE and Cd promoted soil fluorescein diacetate hydrolase (FDA)

Co-liquefaction is an emerging technology aimed at enhancing bio-oil yield and quality, compensating for decrease in feedstock, increasing productivity, and adding revenue to bio-refineries. This study delves into the influence of plastic waste (PW) types during co-liquefaction with cotton gin trash (CGT) on the yield and quality of the produced crude oil. Various plastics, including PLA (polylactic acid), PVA (polyvinyl alcohol), PET (polyethylene terephthalate), LDPE (low-density polyethylene), HDPE (high-density polyethylene), PP (polypropylene), and PS (polystyrene), were investigated in a mixing ratio of 2:1 (CGT/plastic waste) at 320 degrees C and 2 hours in supercritical ethanol (ScEtOH), without catalyst, to produce energy -dense bio-oil under optimised conditions. The study presents the suitability of different types of plastic waste for co-feeding with CGT, along with their synergistic and antagonistic effects on product fraction yield (oil, solid, and gas), and oil energy yield. High bio-oil yields of 54.5 wt%, 53.7 wt%, and 43.1 wt% were achieved during co-liquefaction of CGT with PLA, PET and PVA, respectively. Bio-oil with the highest Higher Heating Values (HHV) was achieved through the coliquefaction of CGT with PVA (30.6 MJ/kg) and PS (31.5 MJ/kg). The solid fractions obtained from co-liquefying CGT with PLA and PVA contained 46.9 wt% and 55.1 wt% carbon, respectively, making them potential sustainable sources for soil amendment. Furthermore, the bio-oils were characterised using gas chromatographymass spectroscopy (GC-MS), two-dimensional nuclear magnetic spectroscopy-heteronuclear single quantum coherence (2D-NMR-HSQC), elemental analysis, fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) to assess their quality and stability. Solid residues were characterised to understand the extent of plastic degradation and their suitable applications. The results indicate that the co-liquefaction of lignocellulosic biomass with plastics represents a viable and promising approach for improving bio-oil quality and extending its shelf life.

Biopolymer stabilization of soils has emerged as a viable solution for enhancing the engineering properties of soils in recent years. Xanthan gum and guar gum are two commonly used biopolymers. When combined, these materials have the ability to create stronger gels or gel strengths comparable to those achieved by using xanthan or guar gum individually, but at lower total concentrations. However, the extent of this synergistic viscosity-enhancing effect on soil improvement remains unclear. This study analyzes the effects of xanthan gum and guar gum on the physical and mechanical properties of clay under both individual and combined conditions using Atterberg limits tests, compaction tests, and triaxial consolidation undrained tests. At a 2% biopolymer content, the liquid limit of clay treated with a combination of XG and GG compounds increases by up to 8.0%, while the plastic limit increases by up to 3.9% compared to clay treated with a single colloid. With an increase in the mixing ratio, the optimal water content initially rises and then declines, peaking at 27.3%. The maximum dry density follows a pattern of initially decreasing and then increasing, with the lowest value recorded at 1.616 gcm-3. Moreover, the shear strength of specimens treated with the XG and GG combination generally surpasses that of specimens treated with XG or GG alone. Furthermore, the combined treatment results in increased plasticity, highlighting its potential to enhance safety and stability in engineering applications.

Arbuscular mycorrhizal fungi (AMF) could establish symbiosis with plant roots, which enhances plant resistance to various stresses, including drought stress and salt stress. Besides AMF, chemical stimulants such as trehalose (Tre) can also play an important role in helping plants alleviate damage of adversity. However, the mechanism of the effect of AMF combined with chemicals on plant stress resistance is unclear. The objective of this study was to explore the synergistic effects of Claroideoglomus etunicatum AMF and exogenous Tre on the antioxidant system, osmoregulation, and resistance-protective substance in plants in response to salt stress. Tomato seedlings were inoculated with Claroideoglomus etunicatum and combined with exogenous Tre in a greenhouse aseptic soil cultivation experiment. We measured the arbuscular mycorrhizal symbiont development, organic matter content, and antioxidant enzyme activity in tomato seedlings. Both AMF and Tre improved the synthesis of chlorophyll content in tomato seedlings; regulated the osmotic substance including soluble sugars, soluble protein, and proline of plants; and increased the activity of superoxide dismutase, peroxidase, and catalase. The combination of AMF and Tre also reduced the accumulation of malondialdehyde and alleviated the damage of harmful substances to plant cells in tomato seedlings. We studied the effects of AMF combined with extraneous Tre on salt tolerance in tomato seedlings, and the results showed that the synergistic treatment of AMF and Tre was more efficient than the effects of AMF inoculation or Tre spraying separately by regulating host substance synthesis, osmosis, and antioxidant enzymes. Our results indicated that the synergistic effects of AMF and Tre increased the plant adaptability against salt damage by enhancing cell osmotic protection and cell antioxidant capacity.IMPORTANCEAMF improve the plant adaptability to salt resistance by increasing mineral absorption and reducing the damage of saline soil. Trehalose plays an important role in plant response to salt damage by regulating osmotic pressure. Together, the use of AMF and trehalose in tomato seedlings proved efficient in regulating host substance synthesis, osmosis, and antioxidant enzymes. These synergistic effects significantly improved seedling adaptability to salt stress by enhancing cell osmotic protection and cell antioxidant capacity, ultimately reducing losses to crops grown on land where salinization has occurred. AMF improve the plant adaptability to salt resistance by increasing mineral absorption and reducing the damage of saline soil. Trehalose plays an important role in plant response to salt damage by regulating osmotic pressure. Together, the use of AMF and trehalose in tomato seedlings proved efficient in regulating host substance synthesis, osmosis, and antioxidant enzymes. These synergistic effects significantly improved seedling adaptability to salt stress by enhancing cell osmotic protection and cell antioxidant capacity, ultimately reducing losses to crops grown on land where salinization has occurred.