Debris flows are a type of natural disaster induced by vegetation-water-soil coupling under external dynamic conditions. Research on the mechanism by which underground plant roots affect the initiation of gulley debris flows is currently limited. To explore this mechanism, we designed 14 groups of controlled field-based simulation experiments. Through monitoring, analysis, calculation, and simulation of the changes in physical parameters, such as volumetric water content, pore-water pressure, and matric suction, during the debris flow initiation process, we revealed that underground plant roots change the pore structure of soil masses. This affects the response time of pore-water pressure to volumetric water content, as well as hydrological processes within soil masses before the initiation of gully debris flows. Underground plant roots increase the peak volumetric water content of rock and soil masses, reduce the rates of increase of volumetric water content and pore-water pressure, and increase the dissipation rate of pore-water pressure. Our results clarify the influence of underground roots on the initiation of gulley debris flows, and also provide support for the initiation warning of gully debris flow. When the peak value of stable volumetric water content is taken as the early warning value, the early warning time of soil with underground plant roots is delayed by 534 to 1253 s. When the stable peak value of pore-water pressure is taken as the early warning value, the early warning time of soil with underground plant roots is delayed by 193 to 1082 s. This study provides a basis for disaster prevention and early warning of gully debris flows in GLP, and also provides ideas and theoretical basis under different vegetation-cover conditions area similar to GLP.

Root mechanical traits, including load for failure in tension (Fr), tensile strength (Tr), tensile strain (epsilon r), modulus of elasticity (Er), and tensile toughness (Wr), are critical for plant anchorage and soil stability. These traits are shaped by root morphology, type (absorptive and transport roots), and mycorrhizal associations (arbuscular mycorrhizal and ectomycorrhizal fungi). This study investigates the relationships among these traits. We examined mechanical traits across eight woody species with different mycorrhizal associations, categorizing roots into absorptive and transport types. Root morphological traits - root diameter (RD), specific root length (SRL), root tissue density (RTD), and root biomass (RB) - were measured. Tensile tests were conducted to assess mechanical properties. Statistical analyses, including regression and principal component analysis (PCA), were used to elucidate trait relationships. Transport roots exhibited superior mechanical properties compared to absorptive roots, with RD and RB showing significant positive correlations with mechanical traits. AM roots demonstrated higher tensile strength, strain, and toughness than EM roots. PCA highlighted RD and SRL as dominant factors influencing root mechanical performance, while RB contributed significantly to transport roots' structural stability. This study underscores the critical role of root morphological traits and mycorrhizal associations in determining mechanical performance. These findings highlight the ecological trade-offs between mechanical stability and resource acquisition, offering novel insights into root functional strategies and their implications for ecosystem stability.

The microbiota, a component of the plant holobiont, plays an active role in the response to biotic and abiotic stresses. Nowadays, with recurrent drought and global warming, a growing challenge in viticulture is being addressed by different practices, including the use of adapted rootstocks. However, the relationships between these practices, abiotic stress and the composition and functions of the rhizosphere microbiota remain to be deciphered. This study aimed to unravel the impact of five rootstocks, water management and the combination of both on the rhizosphere bacterial microbiota in grapevines using shotgun metagenomics approach. The results showed that drought impacted the diversity, composition and functionality of the rhizosphere bacterial community. The genera Mycolicibacterium, Mycobacterium and Rhodococcus, and the bacterial functions, including DNA damage repair, fatty acid synthesis, sugar and amino acid transport, oxidative stress reduction, toxin synthesis and detoxification of exogenous compounds were significantly enriched under drought conditions. Rootstocks also significantly affected the rhizosphere bacterial richness but its influence on diversity and functionality compared to water management was weaker. Some taxa and function could be linked to water managements applied. The interaction between rootstocks and water management further influenced the rhizosphere composition, especially under drought conditions, where distinct clustering was observed for specific rootstocks. The results highlight the importance of conducting multifactorial studies to better understand their impact on shaping functional rhizosphere bacterial communities. This study paves the way for future research on beneficial bacterial inoculation and genetic engineering of rootstock to cope with drought stress.

Plant roots improve the stability of collapsing walls and prevent their collapse; they are thus important for controlling the degree of Benggang erosion in southern China. The vegetation species on the collapsing walls are diverse, and the interaction of the root systems with soil affects the stability of the collapsing walls. Most recent studies have only examined the effects of single plants. In order to investigate the effects of the roots of different vegetation types on the shear strength of soil in collapsing walls and their interaction mechanisms of action, this study was conducted using the roots of the herb Dicranopteris dichotoma and the shrub Melastoma candidum. A direct shear test of indoor remodeled soil was carried out by varying water content (15%, 25%) and herb to shrub root ratio (100:0, 75:25, 50:50, 25:75, and 0:100). The results showed that the shear strength (96.09 kPa) and cohesion (49.26 kPa) of root-containing soil were significantly higher than plain soil (91.77 kPa, 42.17 kPa), and the highest values were obtained when herb to shrub root ratio was 100:0 (113.27 kPa, 62.85 kPa). Here, tensile tests and scanning electron microscopy revealed that the tensile force and tensile strength of the roots of Dicranopteris dichotoma were weaker but effective for maintaining soil stability because of their abundance roots, which could achieve a stronger bond to soil. Simultaneously, herbaceous roots have a small diameter, the Root Area Ratio (RAR) of the roots is larger under the same mass condition, which can better contact with soil and the mechanical properties of roots are fully utilized. Therefore, the soil shear strength is higher and can better resist external damage when herbaceous roots accounts for a larger proportion. The results of this research have implications for the selection and allocation of ecological measures for prevention and control of Benggang.

BackgroundThere is much interest in how roots can be manipulated to improve crop performance in a changing climate, yet root research is made difficult by the challenges of visualising the root system accurately, particularly when grown in natural environments such as soil. Scientists often resort to use of agar- or paper-based assays, which provide unnatural growing media, with the roots often exposed to light. Alternatives include rhizotrons or x-ray computed tomography, which require specialist and expensive pieces of equipment, not accessible to those in developing countries most affected by climate change. Another option is excavation of roots, however, this is time-consuming and near impossible to achieve without some degree of root damage. Therefore, new, affordable but reliable alternatives for root phenotyping are necessary.ResultsThis study reports a novel, low cost, Rootrainer-based system for root phenotyping. Rootrainers were tilted at an angle, in a rhizotron-like set-up. This encouraged root growth on the bottom plane of the Rootrainers, and since Rootrainers open (in a book-like fashion), root growth can be easily observed. This new technique was successfully used to uncover significant genotypic variance in rooting traits for a selection of lettuce (L. sativa) varieties across multiple timepoints.ConclusionThis novel Rootrainertron method has many advantages over existing methods of phenotyping seedling roots. Rootrainers are cheap, and readily available from garden centres, unlike rhizotrons which are expensive and only available from specialist suppliers. Rootrainers allow the roots to grow in substrate medium, providing a significant advantage over agar and paper assays.This approach offers an affordable and relevant root phenotyping option and makes root phenotyping more accessible and applicable for researchers.

Revalorized olive waste impacts root microbiome.Root microbiome modulates plant-induced defense.Insect's exudate simulates the pest attack.The objective of this study was to investigate the combined effect of soil amendments and pest attack on plant-induced defense and their impact on a biological control agent's behavior. The effects of olive mill wastes revalorized through vermicomposting on the aboveground tri-trophic interactions among olive trees (Olea europaea), the olive seed-feeder, Prays oleae, and its natural predator, Chrysoperla carnea, were evaluated. The findings demonstrate that soil nitrogen and organic carbon levels, in conjunction with fungal diversity and functionality within olive roots, exert a significant influence on the volatile compounds emitted by the plant under attack that are most appealing to C. carnea. Moreover, the attractiveness of aerial volatiles was found to correlate with soil organic carbon content and the taxonomic and functional diversity of both bacteria and fungi in the olive root system. It is worthy of note that three particular volatile compounds, namely 5-hepten-2-one-6-methyl, acetic acid and nonanal, were consistently observed to attract C. carnea. These findings highlight the potential of soil amendments to enhance biological control strategies. Future research should prioritise the validation the greenhouse findings through large-scale field trials and the assessment of the practical applications of soil amendments in pest management programmes.

Rising soil salinity poses significant challenges to Mediterranean viticulture. While some rootstocks effectively reduce salt accumulation in grafted scions, the mechanisms and performance of novel rootstocks remain largely unexplored. This study compared two novel M-series rootstocks (M2, M4) with established commercial rootstocks (1103 Paulsen, R110) to evaluate their physiological responses and salt tolerance under irrigation with varying salinity levels (0, 25, 50, and 75 mM NaCl) over 5 months. Growth parameters, photosynthetic efficiency, chlorophyll content (SPAD), ion homeostasis, and visual symptoms were monitored. Results revealed genotype-specific strategies: 1103 Paulsen exhibited robust photosynthetic efficiency and ion exclusion, maintaining growth and chlorophyll stability; M2 demonstrated superior biomass retention and moderate ion compartmentalization but showed reduced photosynthetic performance at higher salinity levels; R110 displayed effective ion management at moderate salinity but experienced significant growth reduction under severe stress; and M4 was the most sensitive, with severe reductions in growth and ion homeostasis. Organ-specific responses highlighted roots acting as primary ion reservoirs, particularly for sodium and calcium; leaves exhibited high potassium and chloride concentrations, critical for photosynthesis but prone to ionic imbalance under stress; and stems and wood played a buffering role, compartmentalizing excess sodium and minimizing damage to photosynthetic tissues. The reported findings provide valuable insights for rootstock selection and breeding programs, particularly for regions facing increasing soil and water salinization challenges.

Studies of fluvial geomorphology should consider the essential roles played by plant communities, in addition to the usual geological and hydrological factors. Mobile-bed flume experiments were undertaken to investigate the effects of vegetation roots on the protection of sandbars from erosion in fluvial channels. Loose sandbars (i.e., containing only sand) and sandbars covered with taproot and fibrous-root vegetation types were used to assess the influence of vegetation on residual sandbar volume and channel erosion in the case of emergent, partly submerged, and submerged sandbars. Results indicate that vegetation roots effectively increase soil cohesion, reducing flow scouring. Fibrous root systems form a root net around sandbars, preventing morphological damage caused by external erosion at low flow rates. Taproots develop solid erosion-inhibiting structures within sandbars through their strong primary and lateral roots, effectively preventing internal scouring at high flow rates. Relative to loose sandbars, vegetated sandbars were 24 %, 121 %, and 222 % more protected from sediment erosion under emergent, partly submerged, and submerged conditions, respectively. The ratio of effective erosion protection increased with increasing discharge, with vegetation roots playing a key role in stabilizing sandbars, particularly under submerged conditions.

Microbial secondary metabolites are crucial in plant-microorganism interactions, regulating plant growth and stress responses. In this study, we found that cyclo(-Phe-Pro), a proline-based cyclic dipeptide secreted by many microorganisms, alleviated aluminum toxicity in wheat roots by increasing root growth, decreasing callose deposition, and decreasing Al accumulation. Cyclo(-Phe-Pro) also significantly reduced Al-induced reactive oxygen species (ROS) with H2O2, O2 center dot-, and center dot OH levels decreasing by 19.1%, 42.8%, and 17.9% in root tips, thus protecting the plasma membrane from oxidative damage. Although Al stress increased the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) in wheat roots, cyclo (-Phe-Pro) application reduced these enzyme activities. However, compared to the Al treatment, cyclo(-Phe-Pro) application increased DPPH and FRAP activities by 16.8% and 14.9%, indicating increased non-enzymatic antioxidant capacity in wheat roots. We observed that Al caused the oxidation of ascorbate (AsA) and glutathione (GSH) to dehydroascorbate (DHA) and glutathione disulfide (GSSG), respectively. Under Al stress, cyclo (-Phe-Pro) treatment maintained reduced AsA and GSH levels, as well as high AsA/DHA and GSH/GSSG redox pair ratios in wheat roots. High AsA/DHA and GSH/GSSG ratios can reduce Al toxicity by neutralizing free radicals and restoring redox homeostasis via antioxidant properties. These results suggest that cyclo(-Phe-Pro) maintains ASA- and GSH-dependent redox homeostasis to alleviate oxidative and Al stress in wheat roots. Findings of this study establishes a theoretical foundation for using microbial metabolites to mitigate Al toxicity in acidic soils, highlighting their potential in sustainable agriculture.

Organic inputs from aboveground litter and underground roots are an important factor affecting nutrient cycling in forest ecosystems. However, we still know little about the seasonal effects of the interaction between aboveground and underground organic inputs on soil organic carbon, nutrients and microorganisms after vegetation restoration in degraded red soil. Therefore, we focused on a mixed forest dominated by Schima superba and Pinus massoniana that had been restored for 27 years on eroded and degraded red soil in a subtropical region. Five treatments were set as follows: retaining aboveground litter + retaining root + retaining mycorrhizae (LRM, control treatment), doubling aboveground litter + retaining root + retaining mycorrhizae (DLRM), removing aboveground litter + retaining root + retaining mycorrhizae (NRM), removing aboveground litter + removing root + retaining mycorrhizae (NNM), and removing aboveground litter + removing root + removing mycorrhizae (NNN). After more than three years of treatment, DLRM, NRM, NNM, and NNN treatments reduced soil moisture content by 32.0-56.8 % in the rainy season compared with the LRM treatment. Soil total nitrogen and ammonium nitrogen concentrations were the highest in the DLRM treatment. Soil ammonium concentration and pH were higher in the rainy season than those in the dry season, while soil nitrate concentration was higher in the dry season. Soil available phosphorus concentration in the dry season decreased by 64.5 % in the DLRM treatment, while they were 2.0-10.7 times of those in the LRM, NRM, NNM, and NNN treatments compared to the rainy season. Soil microbial communities were dominated by bacteria across treatments, accounting for 74.0-75.5 % of the total phospholipid fatty acid (PLFA) of soil microbes, and there was no significant difference among treatments. Except for fungi, the total PLFAs of soil microorganisms and the PLFA content of each microbial taxon were higher in the dry season than those in the rainy season. The F/B value in the rainy season was higher than that in the dry season. The PLFA contents of gram-positive bacteria and actinomyces in the DLRM and NRM treatments were higher than those in the NNM treatment, and PLFA contents of both in the dry season were 1.5 and 1.6 times of those in the rainy season, respectively. Soil total phosphorus and pH had the highest contribution to soil microbial community changes in rainy and dry seasons, respectively. Comprehensive evaluation showed that double aboveground litter addition was more conducive to soil quality improvement. In conclusion, litter, roots and mycorrhiza manipulations affected the PLFA contents of soil microorganisms through the regulation of soil physicochemical properties, rather than the proportions of each microbial taxon in the total PLFAs, which was related to the season. The results can provide a theoretical basis for soil quality improvement as driven by soil microorganisms during the restoration of degraded red soil.