Root Characteristics Research Articles

Interactive effect of tillage and crop residue management on weed dynamics, root characteristics, crop productivity, profitability and nutrient uptake in chickpea (Cicer arietinum L.) under Vertisol of Central India.

Tillage and crop residue management play an imperative role in soil physico-chemical properties that eventually affects crop productivity. The objective of the study to find out a compatible combination of tillage and crop residue management for achieving sustainable food production by improving soil properties, providing favorable environment to crop plants. Secondly, managing crop residues effectively to reduce environmental pollution arising due to crop residue burning. With this aim, a field experiment was conducted on six years continued running experiment under conservation agricultural practices during rabi season of 2019-20 on chickpea. The experiment was comprised of five tillage operations with or without crop residue in main plot and three levels of nutrients in sub plots laid out in split plot design with three replications. Reduced Tillage with 60cm residue height (RT60) was recorded higher growth and yield attributes over conventional tillage practice that attributed to economic yield enhancement. The percent yield increment under NT and RT with 30 and 60cm height residue retention varied from 6.91% to 9.67% over conventional tillage. Maximum grain (2380 kg ha-1) and biological output (5762 kg ha-1) was recorded under RT60 (T4), which ascribed to higher net return (Rs 60551 ha-1) and benefit-cost ratio (2.97). The augmentation in net monetary benefit among tillage systems was lies between 24.32% to 37.78% over conventional tillage. The seed protein content ranged between 20.38 to 21.69% among the treatments. Moreover, total N uptake was maximum under RT60, while total P and K uptake was higher in No Tillage with 30cm residue height (T1). No-Tillage with 60cm residue height (NT60) recorded relatively higher soil moisture content (SMC) (22.71 and 15.40%). Treatment NT30 accrued relatively higher value of soil bulk density (1.42 Mg m-3) followed by NT60 and RT60 in comparison to conventional tillage (1.34 Mg m-3). In conclusion, NT and RT with 60cm residue height along with STCR (N3) nutrient dose was found effective for sustainable food production.

In vitro Regeneration of Potato (Solanum tuberosum L.) Using Sprout Explant

In vitro regeneration ability of four varieties of potato (Solanum tuberosum) was evaluated for plantlet production applying four hormonal concentrations and combinations. Shoot and root characteristics were observed at 15 days after inoculation of sprout explants. There was significant variation found among the four treatments in four studied traits. The genotype Chollisha exhibited superior performance in plantlet production among four genotypes. Out of four hormonal teatments, T3 {MS+ 2, 4- D (2 mg/l) + BAP (2 mg/l)} hormonal combination showed high effectiveness for in vitro plantlet regeneration. Therefore, this protocol might be used in future micropropagation of potato for large scale potato plantlet production.

Morphological Characterization of the Mexican sword Aquarius palifolius (Nees & Mart.) Christenh. & Byng. Family Alismataceae

The Mexican sword (Aquarius palifolius) is an ornamental plant with attractive leaves and flowers. Besides being used as a potted ornamental plant, this plant is also widely used as an aquatic ornamental plant in aquariums because it can adapt to a watery environment. This research is a descriptive study by observing the morphological form of the Mexican sword (A. palifolius) planted in pots at the Green House of the Payakumbuh State Agricultural Polytechnic. The data obtained from the morphological characters of Mexican sword plants in roots, stems, leaves, and flowers were entered the table and analyzed descriptively. Then take photos as research documentation. The results showed that the characteristics of roots that have long soft fibers with white to cream-brown color have a little sap. Whole leaves Undersurface dull. Leaf-blade length 20–25.5 cm, width 16.5–22.5 cm. The surface of the stalk has nine ribs with a length of 29.3–47.7 cm, with a diameter of 6.6–9.8 mm. The midrib length is 8.5–11 cm and has a width of 2.3–2.5 cm. In one clump of plants, there are 9-10 leaves. The petals are 2.5 cm long and 2.6 cm wide. The stamens have 20 to 24 stamens. The filaments are light yellow to light green, and the anthers are yellow. The pistil is supers (above the base of the flower). The results the morphological characteristics of plants that are cultivated in the Harau area of Lima Puluh Kota district using certain pot sizes

Prominent Effects of Zinc Oxide Nanoparticles on Roots of Rice (Oryza sativa L.) Grown under Salinity Stress

The morphological plasticity of plant roots is a key factor in their ability to tolerate a wide range of edaphic stresses. There are many unanswered questions relating to nanotechnology and its potential uses for sustainable agriculture. The main purpose of this study was to examine the effects of salinity-induced morphogenic responses and zinc oxide nanoparticles (ZnO-NPs) on root characteristics, growth, MDA content, antioxidant enzymatic activity, and root ion accumulation in rice (Oryza sativa L.). The experiment was conducted in a hydroponic culture containing 50 mg/L of ZnO-NPs and different concentrations (60, 80, and 100 mM) of NaCl for 14 days. The results indicated a decrease in rice root growth due to exposure to salinity (length, fresh, and root dry weight). The results showed that salinity caused a reduction in rice root growth (length, fresh, and root dry weight). Higher root sodium (Na+) accumulation, MDA content, and potassium level decreased with increasing salinity. Root length, root fresh weight, root dry weight, root K+ content, and root antioxidant enzymatic activity were all enhanced by applying 50 mg/L ZnO-NPs often in salinity. SEM analysis revealed that ZnO-NPs treatments significantly improved root morphology. There was a notable decrease in root Na+ content as a result, which improved the K+/Na+ ratio in the rice’s root system. These findings suggest that O. sativa, when treated with ZnO-NPs, can thrive under salt-stress conditions, opening up the possibility of cultivating the plant in extreme climates.

Reduction in soil detachment capacity by inoculation of bacillus polymyxa strain BcP26 in deforested lands

The beneficial effects of rhizobacteria in increasing plant growth, nutrient uptake and rhizosphere soil aggregation are well known. However, few investigations have explored the impacts of these bacteria on soil erosion processes, particularly for the parameters used in rill erosion. To fill this gap, this investigation has evaluated the effects of growth of Zoysia grass roots induced by bacillus polymyxa strain BcP26 on the rill detachment capacity (Dc) and rill erodibility (Kr) in the treated soil, compared to the control soil by a paired sample t-test with six replications for each experiment in deforested lands of Northern Iran. For measuring Dc, a hydraulic flume was used at five slopes (4.3%–38.2%) and five water discharges (0.29–0.69 l m−1 s−1). Three characteristics of roots including the length, biomass and weight density of roots were measured. Dc was lower (on average - 24% for the average slopes) in the treated soil with the bacillus strain (PB) compared to the control soil (AB). Rill erodibility (Kr), obtained by the relationship between Dc and the shear stress, also was significantly lower (−60%) in the PB soil compared to the control soil. A principal component analysis provided a significant combined factor (the first principal component) that revealed an obvious discrimination in rill detachment capacity between treated and control soils. This value of rill erodibility for deforested lands is contributory for modelling purposes of soil resistance to rill erosion. It is concluded that, thanks to the bacillus strain used as one of plant growth promoting rhizobacteria, soil erosion is significantly (at p < 0.01) reduced, and this strain contributes to reduce the risk of soil degradation.

Physical and chemical characterization of yacon (Smallanthus sonchifolius) roots cultivated with different doses of potassium fertilization

The already marked tendency for functional food consumption, low in calories, and with biologically active properties, has been increasing. In this scenario, yacon tuberous roots, with high levels of nutraceutical fructooligosaccharides, gain importance. However, these nutraceutical properties depend on fertilization management. Thus, our study aims to evaluate different doses of potassium fertilization on the physicochemical characteristics of yacon roots. The experimental design consisted of randomized blocks, with 4 replications and 5 treatments: four doses of potassium fertilization (50%; 100%; 150%; 200%) of the reference value, corresponding to 178.7 kg.ha-1; 357.4 kg.ha-1; 536.1 kg.ha-1; 714.8 kg.ha-1 of potassium chloride – (KCl), and a control (soil without fertilization). The chemical features evaluated were pH, total titratable acidity, soluble solids, conductivity, turbidity, moisture and ashes. The texture profile was analyzed through toughness, adhesiveness, cohesiveness, chewability index, elasticity, and gooeyness. Most of the variables were influenced by potassium soil fertilization. Only turbidity, conductivity and gumminess showed no response to the applied doses, not fitting the tested models. Potassium fertilization improved both chemical (higher levels of soluble solids and less acidity) and physical characteristics (less hardness, chewability, cohesiveness, and adhesion) of yacon tuberous roots, bringing greater quality to the final product. Highlights Yacon is considered a prebiotic food. Several immunostimulatory characteristics promote antimicrobial, anti-inflammatory, and antioxidant activity. Potassium is associated with root size, shape, texture, color, flavor, acidity, nutrient transport resistance, nutritional value, and even market value. Texture constitutes an important factor and quality criterion for the sensory acceptance of food. Thus, the results obtained show that potassium fertilization improves both physical and chemical characteristics of yacon roots. The best results were observed with the maximum dose of potassium fertilization (357.4 kg.ha-1 of KCl).

Optimum Nitrogen Application Acclimatizes Root Morpho-Physiological Traits and Yield Potential in Rice under Subtropical Conditions

Nitrogen (N) is a highly essential macronutrient for plant root growth and grain yield (GY). To assess the relationship among N, root traits, and the yield of boro (dry season irrigated) rice, a pot experiment was performed in the Department of Agronomy, Bangladesh Agricultural University, Mymensingh, Bangladesh, during the boro rice season of 2020-2021. Three boro rice varieties, namely BRRI dhan29, Hira-2, and Binadhan-10, were planted at four N doses: 0 kg ha-1 (N0), 70 kg ha-1 (N70), 140 kg ha-1 (N140), and 210 kg ha-1 (N210). The experiment was conducted following a completely randomized design with three replicates. The varieties were evaluated for root number (RN), root length (RL), root volume (RV), root porosity (RP), leaf area index (LAI), total dry matter (TDM), and yield. The results indicated that the Binadhan-10, Hira-2, and BRRI dhan29 varieties produced better root characteristics under at the N140 and N210 levels. A substantial positive association was noticed between the grain yield and the root traits, except for root porosity. Based on the root traits and growth dynamics, Binadhan-10 performed the best at the N140 level and produced the highest grain yield (26.96 g pot-1), followed by Hira-2 (26.35 g pot-1) and BRRI dhan29 (25.90 g pot-1).

Spatiotemporal dynamics and functional characteristics of the composition of the main fungal taxa in the root microhabitat of Calanthe sieboldii (Orchidaceae)

BackgroundEndophytic fungi play a critical ecological role in the growth and development of orchids, but little is known about the spatial and temporal dynamics of fungal diversity or the ecological functions of fungi during orchid growth and reproduction. Calanthe sieboldii Decne. is listed in the Chinese National Key Protected Wild Plants as a class I protected wild plant. To understand the community characteristics of root and soil fungi of the orchid during its reproductive seasons, we investigated the community composition, spatial and temporal dynamics, and functional characteristics of the orchid microhabitat fungi by using diversity and ecological functional analyses.ResultsWe discovered that there were three, seven, and four dominant fungal families in the orchid's roots, rhizoplane soil, and rhizosphere soil, respectively. Tulasnellaceae, Aspergillaceae, and Tricholomataceae were the dominant fungi in this endangered orchid's microhabitats. The closer the fungal community was to the orchid, the more stable and the less likely the community composition to change significantly over time. The fungal communities of this orchid's roots and rhizoplane soil varied seasonally, while those of the rhizosphere soil varied interannually. Saprophytic fungi were the most abundant in the orchid's fungal community, and the closer the distance to the orchid, the more symbiotic fungi were present.ConclusionsThe fungi in different parts of the root microhabitat of C. sieboldii showed different spatiotemporal dynamic patterns. The fungal community near the orchid roots was relatively stable and displayed seasonal variation, while the community further away from the roots showed greater variation. In addition, compared with the soil fungi, the dominant endophytic fungi were more stable, and these may be key fungi influencing orchid growth and development. Our study on the spatiotemporal dynamics and functions of fungi provides a basis for the comprehensive understanding and utilization of orchid endophytic fungi.

Effects of irrigation at flowering stage on soil nutrient and root distribution in wheat field

To provide theoretical support the full use of water and fertilizer resources for wheat, we explored the effects of irrigation on wheat yield, plant and soil nutrient distribution during flowering period and its relationship with root characteristics. We set up two treatments by using the 2 m deep soil column cultivation method with irrigation during flowering (T1) and no irrigation during flowering (T2), with the drought-resistant and high-yield cultivar Luomai 28 (LM28) and the high photosynthetic efficiency cultivar Bainong 207 (BN207) as materials. We measured contents of nitrogen, phosphorus and potassium in plants and soils, as well as the characteristics of soil roots. The results showed that ammonium, available phosphorus, and available potassium were mainly distributed in 0-80 cm soil layer, and that nitrate was mainly distributed in soil layer below 80 cm during wheat harvest. Irrigation at anthesis stage promoted wheat to absorb ammonium, available phosphorus and available potassium from the upper layer of soil and nitrate nitrogen from the lower layer but did not aggravate the deep leaching of nitrate. The root of wheat mainly concentrated in 0-60 cm soil layer and decreased with increasing soil depth. Dry matter accumulation, total nitrogen and total phosphorus were mainly distributed in wheat grains at maturity, while total potassium was mainly distributed in stems. Irrigation at anthesis stage significantly increased the 100-grain weight of wheat, and consequently the yield. Root morphology was negatively correlated with soil nitrate in 0-40 cm soil layer, positively correlated with soil ammonium in 80-100 cm soil layer and soil available phosphorus in 0-100 cm soil layer. Irrigation at anthesis stage promoted the full absorption of soil nutrients by roots at late filling stage, delayed the senescence of flag leaves after flowering, prolonged the functional period of transporting nutrients from vegetative organs to reproductive organs, leading nutrients in vegetative organs more fully transported to grains, increasing grain weight and yield.

Effect of cryopreservation on plant growth and roots characteristics of red beet (beta vulgaris l.) cultivar

Effect of cryopreservation on plant growth and roots characteristics of red beet (beta vulgaris l.) cultivar

Improving electrochemical characteristics of plant roots by biochar is an efficient mechanism in increasing cations uptake by plants

Electrochemical properties of roots such as zeta potential and cation exchange capacity are important factors that play a critical role in the absorption of nutrients by plants. Adding biochar to the soil may improve the electrochemical properties of the roots and thereby increase absorption of nutrients by plants. Thus, this research was laid out under greenhouse condition to evaluate the possible effects of biochar addition to soil (25 g biochar kg−1 soil) on changing electrochemical properties of roots, nutrients absorption, and growth parameters of safflower (with a deep root system) and mint (with a shallow root system) plants. Biochar noticeably increased pH and cation exchange capacity of soil, safflower and mint growth, calcium, magnesium and iron contents in roots and maximum sorption capacity of these nutrients by plant roots. Electrochemical measurements reveled that biochar application increases negative charges on root surface area (by about 30% and 36% in safflower and mint roots, respectively), cation exchange capacity of roots and root activity in both plants. On the other hand, biochar reduced zeta potential in plant roots (more negative potential). Reduction of zeta potential by biochar application were about 31% and 42% in safflower and mint roots, respectively. The cation-exchange groups (hydroxycinnamic acid + carboxyl groups) were increased due to biochar treatment by about 30% in safflower and 32% in mint roots. As an annual plant with deep roots, safflower roots had more functional groups, cation exchange capacity and root activity than mint plant in both biochar and control conditions. Results of this research showed that biochar not only adjusts physicochemical properties of rhizosphere, but also improves electrochemical specification of plant roots via increasing number of functional groups on root cell walls, which enhances maximum sorption capability of plant roots.

Untargeted metabolism approach reveals difference of varieties of bud and relation among characteristics of grafting seedlings in Camellia oleifera.

Camellia oleifera is one of the essential wood oil trees in the world. C.oleifera was propagated by nurse seedling grafting. Since the scion of C.oleifera had a significant regulated effect on the properties of rootstock after grafting and impacted on the growth of the grafted seedlings, it was necessary to understand the characteristics of buds among varieties to cultivate high-quality grafted seedlings. The metabolome was thought to be a powerful tool for understanding connecting phenotype-genotype interactions, which has an important impact on plant growth and development. In this study, UPLC-MS was used to determine the metabolites of the apical buds of CL3, CL4, CL40, and CL53 spring shoots after 30 days of sprout and to measure the growth characteristics of roots and stems after grafting. Metabolomics analysis revealed 554 kinds of metabolites were significant differences among four varieties, and 29 metabolic pathways were identified to have significant changes (p< 0.05), including carboxylic acids and derivatives, fatty Acyls, organooxygen compounds, and prenol lipids metabolites. The metabolites appeared in all varieties, including phenethyl rutinoside in glycosyl compounds and hovenidulcioside A1 in terpene glycosides. Metabolite-metabolite correlations in varieties revealed more complex patterns in relation to bud and enabled the recognition of key metabolites (e.g., Glutamate, (±)Catechin, GA52, ABA, and cs-Zeatin) affecting grafting and growth ability. Each variety has a unique metabolite type and correlation network relationship. Differentiated metabolites showed different growth trends for development after grafting. Many metabolites regulate the growth of scions in buds before grafting, which plays a crucial role in the growth of seedlings after grafting. It not only regulates the growth of roots but also affects the development of this stem. Finally, those results were associated with the genetic background of each cultivar, showing that metabolites could be potentially used as indicators for the genetic background, indicating that metabolites could potentially be used as indicators for seedling growth characteristics. Together, this study will enrich the theoretical basis of seedling growth and lay a foundation for further research on the molecular regulation mechanism interaction between rootstock and scion, rootstock growth, and the development of grafted seedlings after grafting.

Integrated Metabolomics and Morpho-Biochemical Analyses Reveal a Better Performance of Azospirillum brasilense over Plant-Derived Biostimulants in Counteracting Salt Stress in Tomato.

Increased soil salinity is one of the main concerns in agriculture and food production, and it negatively affects plant growth and crop productivity. In order to mitigate the adverse effects of salinity stress, plant biostimulants (PBs) have been indicated as a promising approach. Indeed, these products have a beneficial effect on plants by acting on primary and secondary metabolism and by inducing the accumulation of protective molecules against oxidative stress. In this context, the present work is aimed at comparatively investigating the effects of microbial (i.e., Azospirillum brasilense) and plant-derived biostimulants in alleviating salt stress in tomato plants by adopting a multidisciplinary approach. To do so, the morphological and biochemical effects were assessed by analyzing the biomass accumulation and root characteristics, the activity of antioxidant enzymes and osmotic stress protection. Furthermore, modifications in the metabolomic profiles of both leaves and root exudates were also investigated by ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC/QTOF-MS). According to the results, biomass accumulation decreased under high salinity. However, the treatment with A. brasilense considerably improved root architecture and increased root biomass by 156% and 118% in non-saline and saline conditions, respectively. The antioxidant enzymes and proline production were enhanced in salinity stress at different levels according to the biostimulant applied. Moreover, the metabolomic analyses pointed out a wide set of processes being affected by salinity and biostimulant interactions. Crucial compounds belonging to secondary metabolism (phenylpropanoids, alkaloids and other N-containing metabolites, and membrane lipids) and phytohormones (brassinosteroids, cytokinins and methylsalicylate) showed the most pronounced modulation. Overall, our results suggest a better performance of A. brasilense in alleviating high salinity than the vegetal-derived protein hydrolysates herein evaluated.

Revisiting Soil Water Potential: Towards a Better Understanding of Soil and Plant Interactions

Soil water potential (SWP) is vital for controlling the various biological and non-biological processes occurring through and across the soil-plant-atmosphere continuum (SPAC). Although the dynamics and mechanisms of SWP have been investigated for several decades, they are not as widely explored in ecohydrology research as soil moisture, due at least partly to the limitation of field observation methods. This limitation restricts the understanding of the responses of plant physiology and ecological processes to the SWP gradient and the ecohydrological functions of SWP dynamics in different contexts. Hence, in this work, we first briefly revisit the origin and development of the concept of SWP and then analyze the comprehensive factors that influence SWP and the improvement of SWP observation techniques at field scales, as well as strategies for developing new sensors for soil water status. We also propose views of focusing on the response characteristics of plant lateral roots, rather than taproots, to SWP dynamics, and using hormone signaling research to evaluate plant response signals to water stress. We end by providing potential challenges and insights that remain in related research, such as the limitations of the SWP evaluation methods and the future development direction of SWP data collection, management, and analysis. We also emphasize directions for the application of SWP in controlling plant pathogens and promoting the efficiency of resource acquisition by plants. In short, these reflections revisit the unique role of SWP in eco-hydrological processes, provide an update on the development of SWP research, and support the assessment of plant drought vulnerability under current and future climatic conditions.

Morphological and anatomical changes of Salicornia roots are associated with different salinity and nutrients conditions in contrasting genotypes

Soil salinity induces morphological and anatomical changes in the roots and shoots of halophytic plants. These variations may be associated with external nutrient factors, including minerals. In this study, we treated the halophyte Salicornia (Amarantheceae) sometimes called sea beans or marsh samphire, with NO3− (0 mM, 6 mM, and 18 mM), NH4+ (0 mM, 1 mM and 3 mM), and NaCl (0 mM, 200 mM and 800 mM). The root characteristics of the two contrasting Salicornia genotypes, Qom (susceptible) and Helleh (tolerant) were then studied using light and epifluorescence microscopy and scanning electron microscopy. An anatomical study showed that salinity increased the diameter of the xylem cell wall. It also promoted fiber network development in the Helleh and the Qom genotypes leading to lower root and shoot biomass formation. In contrast, increased NH4+ or NO3+ and salinity enhanced root biomass formation and longer root length. Combined NH4+ or NO3+ and salinity were more positively associated with endoderm lignification, increased parenchyma diameter, and the large to small ratio of parenchyma of the stele indicating that a significant root structural plasticity underlies the adaptation mechanism of the salt tolerance in different Salicornia genotypes. In light of our results, we recommend paying more attention to genotype-dependent nutrition application under salinity and promoting saline agriculture.

Straw incorporation and nitrogen reduction effect on the uptake and use efficiency of nitrogen as well as soil CO2 emission of relay strip intercropped soybean.

Intercropping can increase crop N uptake and reduce carbon emissions. However, the effects of straw incorporation and N reduction on N use and carbon emissions in intercropping are still unclear. We explored the mechanism of N uptake, N use efficiency, and CO2 emissions in the wheat-maize-soybean relay strip intercropping system. A two-year field experiment was conducted with two straw managements, i.e., wheat straw incorporation (SI) and straw removal (SR), and four N application levels of soybean, i.e., 60 (N60), 30 (N30), 15 (N15), and 0 kg N ha-1 (N0). We assessed soil properties, CO2 emissions, and characteristics of roots, nodules, and aboveground N uptake of intercropped soybean. Results showed that geometry mean diameter of aggregate, soil porosity, soil total N, and soil urease activity were notably greater in SI than in SR. N input reduced from N60 to N30 did not significantly affect the soil total N content and urease activity in SI. The root length, root surface area, root volume, root biomass, root bleeding intensity, and inorganic N content of bleeding sap were greater in SI than in SR. In the SI, although the root length and surface area peaked at N60, the root biomass and inorganic N content of bleeding sap were insignificant between N60 and N30. The nodule number, nodule dry weight, nodule nitrogenase activity, and nodule nitrogen fixation potential in SI were notably increased compared with SR. The nodule nitrogen fixation potential in SI notably increased with the decrease of N input at the R3 stage, but it peaked in N30 at the R5 stage. On average, the aboveground N uptake and nitrogen recovery efficiency (RE) was notably higher by 43.7% and 76.8% in SI than in SR. SI+N30 achieved the greatest aboveground N uptake and RE. The CO2 emission and accumulated CO2 emission were notably greater in SI than in SR, and the accumulated CO2 emission of SI was the lowest with N30 input. In conclusion, SI+N30 promoted N uptake and utilization efficiency with reduced CO2 emissions during the soybean cropping season. It provides a potential strategy for sustainable agricultural development in intercropping systems.

Impact of Root Distribution Characteristics on the Overturning Resistance of Leucaena leucocephala Forest in Debris-Flow Accumulation Area, Dawazi Gully, Yunnan, China

Tree resistance to overturning is crucial in forestry hazard applications and management. Tree anchorage varies considerably with species, tree age, and site conditions. We investigate the relationship between the root characteristics of the overturning slip surface and the role of roots (regarding different diameters in overturning). Four Leucaena leucocephala were fully excavated by a quadrate monolith to establish root distribution characteristics, and 19 L. leucocephala were uprooted until the trees completely overturned to measure the anchoring resistance to overturning. A model was developed to improve the descriptions of root characteristics in the mechanical processes for tree overturning. The results show that the distribution characteristics of the root system were well described by the model. For the root–soil plate radius, the thickest root diameter and the root biomass of different diameters at the overturning slip surface increased with the diameter at the breast height. The root biomass affected the strength of the overturning slip surface; the root density may be a key factor in identifying the location of the overturning slip surface. The model could predict the overturning moment of most overturned trees; although it overestimated the overturning moment for small diameters at breast height trees, the results will be useful for understanding the influence of root distribution characteristics in overturning.

Effects of Herbaceous Plant Roots on the Soil Shear Strength of the Collapsing Walls of Benggang in Southeast China

Failure of collapsing walls is an important process affecting the development of Benggang and is closely related to the soil shear strength. Plant roots can increase the soil shear strength. However, the effects and mechanisms of root reinforcement on the soil shear strength of collapsing walls remain unclear. To explore the shear strength characteristics of collapsing walls and their influencing factors under different vegetation conditions, Pennisetum sinese, Dicranopteris dichotoma, Odontosoria chinensis, and Neyraudia reynaudiana were adopted as experimental objects in the Benggang district of Anxi County, Southeast China. We measured the root characteristics and in situ shear strength of root–soil complexes by dividing soil with the four vegetation conditions into five soil layers: 0–5 cm, 5–10 cm, 10–15 cm, 15–20 cm, and 20–25 cm. The average shear strength of the root–soil complexes of the various plants ranked as follows: Pennisetum sinese (30.95 kPa) &gt; Odontosoria chinensis (28.08 kPa) &gt; Dicranopteris dichotoma (21.24 kPa) &gt; Neyraudia reynaudiana (14.99 kPa) &gt; bare soil (11.93 kPa). The enhancement effect of the root system on the soil shear strength was mainly manifested in the 0–5 cm soil surface layer. The soil shear strength attained an extremely significant positive correlation with the root length density, root surface area density, root volume density, root biomass density, for root diameters (L) less than or equal to 0.5 mm and between 0.5 and 1 mm, the soil shear strength could be simulated by using root volume density. The shear strength of undisturbed root–soil complexes measured with a 14.10 pocket vane tester was higher than the value obtained with the Wu–Waldron model (WWM). The correction coefficient k′ varied between 0.20 and 20.25, mostly exceeding 1, and the average correction coefficient k′ value was 4.94. The average correction coefficient determined in this test can be considered to modify the WWM model when conducting experiments under similar conditions.

Effects of Tree Species on Moso Bamboo (Phyllostachys edulis (Carriere) J. Houzeau) Fine Root Morphology, Biomass, and Soil Properties in Bamboo–Broadleaf Mixed Forests

Understanding fine root characteristics in relation to soil properties of bamboo–broadleaf mixed forests may help optimize belowground production management and ecological functions in mixed-forest ecosystems. In this study, we compared four different bamboo–broadleaf mixed forests: Castanopsis chinensis (Sprengel) Hance with moso bamboo (CCB), Alniphyllum fortunei (Hemsl.) Makino with moso bamboo (AFB), Choerospondias axillaris (Roxb.) Burtt and Hill with moso bamboo (CAB), and Castanopsis fargesii Franch with moso bamboo (CFB), and analyzed their effects on the traits of fine roots of moso bamboo, soil nutrient contents, and enzyme activities. In January 2022, fine root and soil samples from four different mixed bamboo–broadleaf forests were collected from a subtropical region of Fujian Province, China. Results showed that CAB significantly increased fine root biomass (FRB) and root length density (RLD); however, specific root length (SRL) was only in the 0–20 cm soil layer. Specific surface area (SSA) was significantly reduced in the CCB in the 0–20 cm and 20–40 cm soil layers. The total phosphorous (TP) and total potassium (TK) contents of AFB and CAB were significantly increased (p &lt; 0.05), and the alkali-hydrolyzable nitrogen (AN) content was significantly increased by CCB in the 0–20 cm soil layer (p &lt; 0.05). Additionally, CFB increased the activities of acid phosphatase (ACP) and catalase (CAT) but decreased the activity of sucrase (SC). Principal component analysis showed that fine root traits (FRB, RLD, SRL, and SSA) were not only positively associated with soil organic carbon (SOC), total nitrogen (TN) and available potassium (AK) but also associated with urease (UE) and CAT. Therefore, belowground interactions between different species have a significant impact on the characteristics of fine roots and soil in bamboo–broadleaf mixed forests.

Field application of biodegradable microplastics has no significant effect on plant and soil health in the short term

Bioplastics (biodegradable plastics) potentially offer an encouraging alternative to conventional (petroleum-based) plastics. In practice, bioplastics inevitably generate a large number of bio-microplastics (bio-MPs, diameter <5 mm) during the degradation progress. However, the impact of bio-MPs on plant and soil health within agroecosystems remains incomplete. Here, a field study was conducted to investigate the effect of two shapes (fiber and powder) of pure polylactic acid (PLA) bio-MPs on oat (Avena sativa L.) and soybean (Glycinemax (L.) Merr.) growth and soil health. Our results showed that PLA application at a representative soil loading rate of 0.2% (w/w) had no significant effect on soil enzyme activities, soil physicochemical properties (soil water content, pH, etc.), root characteristics, plant biomass, and crop yield. Thus, we conclude that soil quality, plant health, and ecosystem multifunctionality were not affected by PLA over one growing season (5 months) in the presence of either bio-MP shape (fiber and powder) for either crop species (oat and soybean). Overall, PLA based bio-MPs may not pose a significant threat to agroecosystem functions in the short term (days to months) in the field, thus may provide a viable environmentally benign solution to replace traditional non-biodegradable plastics in agroecosystems.