Root Characteristics Research Articles

Exogenous IAA enhances low potassium tolerance of sweetpotato by regulating root response strategy

ABSTRACT Plant roots are sensitive to potassium (K+) deficiency signals. Therefore, regulating root growth by exogenous methods is a vital strategy to improve low K+ tolerance of sweetpotato. We studied the effects of exogenous indole-3-acetic acid (IAA) on growth, K+ absorption, and root characteristics in sweetpotato exposed to low K+ treatment (LK). LK significantly inhibited dry mass, K+ concentration and accumulation, as well as the root elongation (length) and branching (forks and crossings) in sweetpotato seedlings. However, exogenous IAA increased the length, ratio, and density of lateral roots and promoted absorption and accumulation of K+, which effectively alleviated the inhibitory effect of low K+. Exogenous IAA also increased the expression levels of auxin synthesis (IbYUC6 and IbTAR2) and transport (IbPIN1, IbPIN3, and IbPIN8) genes in leaves and roots, which promoted the increase of endogenous IAA content. Furthermore, exogenous IAA was more effective on low-K-tolerant variety (XS32) than low-K-sensitive variety (NZ1) under LK stress, depending on their different IAA synthesis and transport strategies. These results indicated that exogenous IAA enhanced root responsiveness of sweetpotato to low K+ stress by modulating auxin biosynthesis and transport, thereby improving the tolerance of sweetpotato to low K+ stress.

Mulched drip irrigation and maize straw biochar increase peanut yield by regulating soil nitrogen, photosynthesis and root in arid regions

Biochar has been increasingly recognized as a valuable soil conditioner, which is beneficial to peanut yield improvement. We conducted a three-year field experiment to investigate the effect of biochar applied at three rates (0 t ha−1 (B0), 24 t ha−1 (B1), and 48 t ha−1 (B2), which were 0%, 1%, 2% of the soil mass) on diurnal variation of net photosynthetic rate, soil available nitrogen (N), root characteristics, and peanut yield under two irrigation methods: CK (drip irrigation) and MDI (mulched drip irrigation). A biochar application rate of 24 t ha−1 (B1) increased soil available N, net photosynthetic rate of leaves, and relative chlorophyll values (SPAD) compared to B0. B1 increased total root length, root surface area, root volume and root bleeding sap (RBS) by 8.5∼29.9%, 13.5∼18.5%, 0.8∼12.1%, and 27.6–45.9%, respectively, compared to B0. Significant correlations between grain yield, SPAD, and RBS indicated that biochar enhanced grain yield by improving photosynthesis and root activity. For the irrigation treatments, MDI significantly increased peanut yield, net photosynthetic rate, and RBS, but had no significant effect on soil available N. High biochar application under MDI (IMDIB2) reduced peanut yield in 2020. Moderate biochar application under MDI (IMDIB1) had the highest peanut yield in three years. These results showed that 24 t ha−1 biochar combined with MDI achieved the highest soil available N, root development, and net photosynthetic rate thus which resulted in the highest grain yield, and this could be a management strategy to increase peanut yield.

Engineering and bio‐chemical properties of asparagus roots (Asparagus racemosus L.)

AbstractThe post‐harvesting procedures, such as grading, washing, transporting, and packaging can be made better with understanding of the attributes of agricultural commodities. The paper aims to estimate the asparagus roots' thermal, physical, and biochemical characteristics. The asparagus was found to vary in the range of 6.26–13.60 cm long. The width and thickness of the root were almost the same and ranged from .69 to 1.10 cm. The bulk density, true density, and porosity ranged from .561 to .771 g/cm3, 1.418 to 2.124 g cm3, and 60.437 to 63.689%, respectively. The water activity of the roots was observed to be in the range of .797–.828. The color characteristics of asparagus roots were found to be L* = 45.46, a* = 6.94, and b* = 23.23. The obtained values of the following thermal variables were: thermal diffusivity = 8.176 × 10−8 m2/s, thermal conductivity = .493 W/m °C, specific heat = 3.424 kJ/kg °C, and latent heat = 23442.74 J/kg. The total phenolic and tannin content in the roots were observed to be 24.41 ± .09 mg of gallic acid equivalent (GAE)/g and 1.73 ± .06 mg of tannic acid equivalent (TAE)/g, respectively. The flavonoid content in the roots was 10.33 ± .04 mg of quercetin equivalent (QE)/g. The root samples were found to be a high capacity to scavenge free radicals and also contain phytochemical components that may prove valuable in future research to combat oxidative stress. The findings of this study will also be advantageous in developing handling and processing equipment for the industrial production of asparagus root products.Practical applicationsAsparagus is a medicinal plant which is now widely used in food processing to produce the fortified‐functional food products because of its high nutritional and medicinal properties. The grading, sorting, conveying, pulping, processing, and handling equipment for various horticultural goods, including asparagus, are designed using machine designing parameters, which are vital and essential parameters. The size and shape of all agricultural commodities varies. The slight modifications to size and form could reduce the effectiveness of numerous procedures and their associated machinery. Therefore, the knowledge about these engineering and biochemical properties of asparagus will inspire researchers to create and upgrade machinery used for grading, sorting, conveying, pulping, and processing.

Sugar Beet Rooting Pattern Mediates Stomatal and Transpiration Responses to Progressive Water Stress

Water stress is the main risk facing sugar beet production in Europe and is expected to worsen with climate change. Therefore, future production essentially depends on the traits that sustain growth during water shortages. In this study, we investigated the interplay of stomatal conductance and transpiration rate as well as the root characteristics of six sugar beet cultivars in a climate chamber experiment under environmental conditions progressing from a non-stressed initial state toward high atmospheric water demand, followed by reduced soil water supply and then by a combination of high demand and low supply. Stomatal conductance quickly responded to changing conditions, dropping from 406.4 to 42.5 mmol m−2 s−1, one order of magnitude, with the transition to reduced soil water availability. The transpiration rate showed a slightly delayed response compared with stomatal conductance, while we observed an inverse influence on the subsequent stomatal behavior exerted by the depletion/conservation of available soil water. The rooting pattern substantially differed among genotypes, predominantly at depths between 60 and 80 cm, where 50.5% of the root length was allocated. Longer roots buffered the effects of the reduction in stomatal conductance at the onset of water supply limitation, with 5.4 mmol m−2 s−1 higher conductance per 100 cm of root length. Therefore, breeding and/or management measures targeting root system vigor are the key to the growth maintenance of sugar beet during dry periods.

Characterization of Rice (Oryza sativa L.) Germplasm for Early Seedling Vigour-related Traits under Direct Seeded Condition

In pursuit of boosting rice production while maintaining economic feasibility within resource constraints, the shift from the traditional puddled-transplanted rice system to direct-seeded rice is gaining significance. Early seedling vigour (ESV) is an important character crucial for direct-seeded rice to outcompete and suppress weed growth. This study evaluated hundred rice germplasm accessions for their early seedling vigour-related traits. Mesocotyl and coleoptile lengths, chlorophyll content, alpha-amylase, speed of emergence, shoot and root characteristics, and vigour indices exhibited notable variability as indicated by their high PCV and GCV. Moreover, they were predominantly under the influence of additive gene effects, as illustrated by their high heritability and genetic advance as per cent of mean. This suggests that these traits are heritable and could be effectively exploited through selective breeding efforts. Positive correlations were found between seedling vigour and traits like emergence (%), speed of emergence, chlorophyll content, and alpha-amylase activity. Based on PCA, Vigour index-I, II, total seedling length, and chlorophyll contents were regarded as major discriminators in rice germplasm for direct seeded traits. The superior genotypes for seedling vigour such as Honduras and Gharib, could be used as donors in the rice breeding programs to develop direct seeded rice cultivars.

Adaptation of rhizosphere bacterial communities of drought-resistant sugarcane varieties under different degrees of drought stress.

Sugarcane is highly sensitive to changes in moisture, and increased drought severely restricts its growth and productivity. Recent studies have shown that plant growth-promoting microorganisms are essential to reduce the adverse effects of environmental stresses, especially drought. However, our knowledge about the dynamics of rhizosphere microbial community structure in sugarcane under varying degrees of drought stress is limited. We analyzed the effects of different degrees of drought stress on the rhizosphere microbial communities of Zhongzhe 1(ZZ1) and Zhongzhe 6(ZZ6) with differences in drought resistance, by combining soil enzyme activity, nutrient content, and physiological and morphological characteristics of sugarcane roots. The results showed that rhizosphere bacterial community began to change at a field capacity of 50%, enriching the sugarcane rhizosphere with drought-resistant bacteria. The core strains of ZZ1 and ZZ6 rhizosphere enrichment were mainly Streptomycetales, Sphingomonadales, and Rhizobiales. However, compared to ZZ1, the changes in rhizosphere bacterial abundance in ZZ6 were primarily associated with the abundance of Streptomycetales as drought levels increased. Rhizobiales and Streptomycetales, enriched in the rhizosphere of ZZ6 under drought, were positively correlated with root tip number and total root length (TRL), increasing the distribution area of roots and, thus, improving water and nutrient uptake by the roots thereby enhancing the resistance of sugarcane to drought stress. This research enhances our understanding of the composition of the rhizosphere microbial community in sugarcane under different levels of drought stress and its interaction with the roots, thereby providing valuable insights for enhancing drought resistance in sugarcane. IMPORTANCE Drought stress is expected to further increase in intensity, frequency, and duration, causing substantial losses in sugarcane yields. Here, we exposed sugarcane to varying degrees of drought treatment during growth and quantified the eventual composition of the resulting sugarcane rhizosphere bacterial community groups. We found that sugarcane rhizosphere under mild drought began to recruit specific bacterial communities to resist drought stress and used the interactions of root tip number, total root length, and drought-resistant strains to improve sugarcane survival under drought. This research provides a theoretical basis for the rhizosphere microbiome to help sugarcane improve its resistance under different levels of drought stress.

Phosphate Fertilizer Type and Liming Affect the Growth and Phosphorus Uptake of Two Maize Cultivars

In the context of phosphorus (P) exhaustion and low P use efficiency (PUE) in crop production, a field trial was designed on a low-P soil in southwestern Germany in 2020 and 2021 to investigate the effects of P fertilizer type and liming on maize growth and P uptake and PUE. The experimental factors were (i) two P fertilizer types, rock phosphate (RP) and diammonium phosphate (DAP); (ii) lime application, lime and no lime; and (iii) two maize cultivars. The results showed that RP resulted in a lower leaf area index and light interception compared with DAP, a 33% lower silage yield, and a 29% lower P content at harvest. The PUE of RP was 18%, which was 37% lower than DAP. Soil liming reduced shoot biomass and led to 35% less shoot P content at the six-leaf stage. The maize cultivar Stabil expressed higher yielding and P acquisition characteristics. In conclusion, DAP cannot be replaced by placed RP, regardless of the lime application in silage maize production in this study. Future research on the PUE of maize cultivars should also consider root characteristics in response to P fertilizer type and soil pH.

Persistent soil organic carbon deficits from converting primary forests to plantations and secondary forests in subtropical China

Soil organic carbon (SOC) plays a critical role in supporting key ecosystem functions and services for humanity. Despite the widespread conversion of primary forests to plantations and secondary forests, it remains uncertain how it affects the content and distribution of SOC. We evaluated SOC content, its components in two fractions, particulate organic carbon (a mean residence time shorter than decades) and mineral-associated organic carbon (a mean residence time of multiple decades to centuries), and the fine root characteristics (biomass, necromass, and C: N of dead fine roots) across Chinese fir plantations and secondary forests during stand development (5–41 years old) in subtropical China, employing primary forests as a reference. We found that SOC content differed significantly between forest types and soil depths, but not with stand age within plantations or secondary forests. In the topsoil (0–10 cm), the SOC content of primary and secondary forests was 47 % and 25 % higher than that of Chinese fir plantations, respectively. The SOC content in the subsoil (40–60 cm) was approximately 6 ± 1.7 mg C g−1 and did not change significantly with forest types or stand ages. The higher SOC contents in primary forests and secondary forests in topsoil resulted primarily from particulate organic carbon accumulation caused by higher fine root biomass and dead root C: N. The fraction of mineral-associated organic carbon to SOC increased with soil depth and was higher in Chinese fir plantations than in secondary forests, suggesting that more SOC is composed of mineral-associated organic carbon that was associated with a higher amount of fine root necromass. Contrary to our expectations, we found SOC content or its fractions did not increase with 40 years of plantation and secondary forest development. Our results reveal persistent SOC deficits from converting primary forests to plantations and secondary forests and highlight the urgent need to conserve the remaining primary forests and protect secondary forests and plantations from disturbances, allowing them to evolve towards older-aged primary forests.

Phenotypic Characterization, Evaluation, and Classification of Cassava (Manihot esculenta Crantz) Accessions in Ethiopia

Cassava has a crucial role in benefiting smallholder farmers as the main food and income source in southern Ethiopia. Characterization accessions are crucial for assessing variation, classifying, and identifying desirable accessions for crop improvement and conservation. In this regard, there needs to be more information on the morphological characterization and classification cassava accessions. Thus, the aim of this research was to systematically characterize, evaluate, and classify cassava accessions using qualitative characters to provide useful information for breeding program and conservation. A total of 64 accessions were planted using a simple lattice design during the 2020-2021 cropping season. Thirty qualitative data were collected at 3, 6, 9, and 18 months after planting and analyzed using the SAS and R-software packages. The high variable characteristics were the shape of the central leaflet, petiole color, leaf retention, branching habit, the color of the stem epidermis, the color of the stem exterior, the external color of the storage root, and the color of the root pulp towards frequency distribution analysis. The Shannon–Weaver diversity index ranged from 0.24 to 1.47, with an overall mean of 0.84. The first three dimensions in the multiple correspondent method explained approximately 39.39% of the total variation, with Dim 1 accounting for 20.77% and Dim 2 accounting for 9.98%, while petiole color and texture of the root epidermis were the leading contributors to the total variation, respectively. In clustering analysis, 64 accessions were classified into 4 clusters of varying sizes. The distribution of accessions in each cluster revealed that 52 accessions were in cluster I, 6 in cluster II, 5 in cluster III, and 1 in cluster IV. Each cluster was varied by a major group characteristic that it represented. Furthermore, the study identified the desirable accessions for desired storage root characteristics such as root constrictions, the external color of the storage root, the color of root pulp, the color of the root cortex, and cortex peeling tendency. In conclusion, the various analyses performed indicated the existence of sufficient genetic variability for the characteristics evaluated, which could be attributed to the dissimilar genetic backgrounds of the evaluated accessions. Thus, these could be utilized for breeding work and conservation.

Effects of Shading on the Growth and Photosynthetic Fluorescence Characteristics of Castanopsis hystrix Seedlings of Top Community-Building Species in Southern Subtropical China

Castanopsis hystrix is a major community-building species in the top communities of southern subtropical China, with a high natural regeneration capacity. However, excessive logging and the introduction of exotic tree species have substantially reduced the area of natural forest patches of Castanopsis hystrix, and seedling regeneration is essential for the long-term continuation of Castanopsis hystrix populations. To explore the effects of light intensity on the seedling emergence and early growth of Castanopsis hystrix, shading experiments were conducted under four shading treatments (0%, 40%, 60%, and 80%). The growth, biomass accumulation, and distribution, the quality index of seedlings, the morphology and structure of the root systems of seedlings, and the leaf chlorophyll content and chlorophyll fluorescence properties of seedlings under different shading treatments were analyzed. The results displayed the following: (1) Shade intensity impacts growth of Castanopsis hystrix seedlings and biomass allocation, with optimal results observed at 60% shade, leading to the promotion of organic matter production in leaves and the limitation of stem growth. (2) Using a multi-indicator composite index, it was determined that seedling quality for Castanopsis hystrix peaks at 60% shade intensity. (3) Shade significantly impacts the morphology and structure of Castanopsis hystrix’s root system, with most root characteristics peaking at 60% shade, indicating a substantial increase in root development compared to no-shade conditions. (4) The D-values indicated the most suitable shade intensity for seedling growth to be 60%, suggesting that Castanopsis hystrix seedlings are sensitive to light and excessive light can be detrimental to their growth. (5) The 60% shade treatment showed the maximum values of chlorophyll fluorescence characteristics and photochemical activity, with variations in energy conversion efficiency and dissipation reflected in parameters like photochemical burst coefficient (qP), photochemical burst coefficient (qN), the actual photometric yield of PSII under light acclimation (YII), and the maximum photosynthetic electron transport rate in photoinhibition (ETR), thereby supporting seedling growth and maintaining the normal function of photosynthetic organs. In conclusion, 60% shade treatment can effectively improve the growth and photosynthetic characteristics of Castanopsis hystrix seedlings and promote the accumulation of nutrient elements, ultimately promoting their growth.

The role of extracellular polysaccharide produced by Bradyrhizobium strain in root growth, improvement of soil aggregate stability and reduction of soil detachment capacity

It is well demonstrated that the production of extracellular polysaccharide by bacteria, as biological binding agent, can increase soil aggregate stability. Also, plant roots have significant effects on the soil erosion rates, since they can strongly change the soil detachment capacity (Dc). This study quantifies Dc at different flow rates in soils treated with biofertilizer under four species (Alnus subcordata, Brachythecium plumose, Gleditsia caspica and Sambucus ebulus species) in the Saravan forest park of Iran and develops regression equations for predicting Dc. Undisturbed samples collected from soils with the four tree species and subjected to five slopes (from 4.2 to 38.3%) and five water discharges (from 0.28 to 0.71 L m−1 s−1) using a hydraulic flume. The results showed that Dc was significantly lower in soils with Alnus subcordata species compared to Brachythecium plumose, Gleditsia caspica and Sambucus ebulus species, as the consequence of the changes in the root characteristics, mean weight diameter (MWD) and macronutrients, so that Dc was negatively correlated with root weight density, root length and root biomass. A linear regression model was found for MWD as a function of extracellular polysaccharide concentration (R2 = 0.74). The unit stream power had high accuracy for predicting Dc for all of the studied species. The lowest value of rill erodibility (Kr) was obtained in soils with Alnus subcordata species using regression relationship between the Dc and the shear stress of the soil. This experiment helped to show the importance of microorganisms in reducing the soil detachment rates and provided a contribution in understanding the choice of appropriate species for soil conservation.

Varietal responses of root characteristics to low nitrogen application explain the differing nitrogen uptake and grain yield in two rice varieties.

Rice root characteristics are tightly associated with high-efficient nitrogen uptake. To understand the relationship of root plastic responses with nitrogen uptake when reducing nitrogen application for green rice production, a hydroponic experiment and a soil pot experiment were conducted under high (HN) and low (LN) nitrogen applications, using two rice (Oryza sativa L.) varieties, NK57 and YD6, three nitrogen absorption traits (total nitrogen accumulation, net NH4 + influx on root surface, nitrogen uptake via apoplasmic pathway) and root characteristics were investigated. In comparison with HN, LN significantly reduced nitrogen absorption and grain yield in both varieties. Concomitantly, there was a decrease in total root length, root surface area, root number, root volume, and root cortical area under LN, while single root length, root aerenchyma area, and root lignin content increased. The expression of OsAMT1;1 and OsAMT1;2 down-regulated in both varieties. The findings revealed that YD6 had smaller reduction degree for the three nitrogen absorption traits and grain yield, accompanied by smaller reduction degree in total root length, root surface area, root cortical area, and expression of the two genes under LN. These root characteristics were significantly and positively correlated with the three nitrogen absorption traits and grain yield, especially under LN. These results indicate that a large root system, lower reduction degree in several root characters, and high expression of OsAMT genes in YD6 explains its high nitrogen accumulation and grain yield under reduced nitrogen application. The study may provide rationale for developing varieties with low nitrogen fertilizer requirements for enabling green rice production.

The impact of water level changes on the growth and physiology of Arundo donax var. versicolor

In order to investigate the effects of water level changes on the growth and physiology of Arundo donax var. versicolor and to understand its adaptive mechanisms to water level fluctuations, this study was conducted. A. donax var. versicolor was selected as the experimental species, and a dual-pot method was employed to simulate both rising and falling water level conditions. The study analyzed morphological characteristics (plant height, stem diameter, leaf traits, root traits), biomass, and photosynthetic features (chlorophyll a, chlorophyll b, chlorophyll a + b, carotenoids) of A. donax var. versicolor under these two water level conditions. The results revealed that (1) under the condition of rising water level, the morphological characteristics and chlorophyll content showed an overall trend of increasing initially and then decreasing with the increase of the rate. The growth rate of 0.2–0.4 cm/d groups were better, while exceeding its tolerance range led to a decrease in photosynthetic pigment content and even cell inactivation. (2) falling water level were more complex, with plant height, stem diameter, leaf length, leaf width, and leaf area being higher in the 0.8–1 cm/d groups, but values for leaf number and root characteristics were lower. This suggests that moderate stress can promote the growth of A. donax var. versicolor, but in the later stages, it can lead to leaf yellowing, root shrinkage, and even death.

Targeted control of soil erosion through selective regulation of Eleocharis yokoscensis using mixed endophytes

Plant root traits play a crucial role in controlling soil erosion and environmental pollution. However, the mechanisms underlying their impact on erosion risks remain unclear due to a lack of effective methods for adjusting root characteristics. In this study, we successfully enhanced the root characteristics and root-soil binding capacity of Eleocharis yokoscensis by employing a combination of soaking and spraying with mixed endophytic bacteria. Experimental results on slopes of 15°, 30°, and 45° demonstrated the efficacy of the mixed endophytes (MIX2.1) treatment in reducing runoff by 23.9607 L/m2 (Quartz Soil), 61.6776 L/m2 (Sandy Soil), and 5.9841 L/m2 (Red Soil), respectively. Additionally, infiltration rates increased by 104% (Quartz Soil), 67% (Black Soil), and 86% (Red Soil), while sediment loads decreased by 86% (Quartz Soil), 70% (Black Soil), and 56% (Black Soil). To predict erosion prevention, we proposed and calibrated a novel method called the Root-Soil Cohesion Ratio (RSCR). Furthermore, weight and correlation analysis revealed intriguing relationships between root characteristics and soil erosion parameters, particularly on steeper slopes where some relationships were reversed. Specifically, the presence of endophytes increased root complexity, but the uncontrolled direction of fibrous roots disrupted rainwater descent channels, impeding infiltration. Conversely, the orientation of lateral roots in the soil positively influenced water infiltration. Moreover, smaller particle gaps in the soil hindered rainwater infiltration to a lesser extent under high slope conditions. In conclusion, selectively modulating plant root traits and regulating specific soil erosion parameters in conjunction with slope factors are vital for effective erosion control. The findings of this study offer valuable engineering implications for utilizing plants in erosion-prone areas to enhance land stability and contribute to erosion restoration efforts.

DIVERSITY OF NEPHENTHES SPP SPECIES IN THE EDUCATION FOREST OF MUHAMMADIYAH UNIVERSITY OF PALANGKA RAYA

Biodiversity, one of which is the diversity of species of Nepenthes spp, is a natural wealth owned by the Education Forest of the Muhammadiyah University of Palangkaraya, Rakumpit, Palangka Raya City, Central Kalimantan. The research uses observation techniques and transect techniques as well as literature documentation as a supporting source with this type of exploratory research. The diversity of Nepenthes spp species obtained in the Educational Forest of Muhammadiyah University of Palangkaraya, namely found 6 (six) species with different characteristics of roots, stems and leaves. Nepenthes spp species found included Nepenthes ampullaria jack, Nepenthes rafflesiana jack, Nepenthes reinwardtiana miq, Nepenthes hirsute, Nepenthes garcilis, and Nepenthes tomoriana.

The effect of different canopy composition of shrublands on soil quality indicators in a semi-arid climate of Iran

Mountain shrublands in semi-arid regions have a prominent role in regulating ecosystem services. Crataegus is a shrub distributed in wide areas of mountain semi-arid zones of the world. However, the effect of shrublands on soil quality indicators, especially fertility and biological activities, is poorly studied. In this study, the effect of various land covers with Crataegus melanocarpa M. B. (CM), Berberis integerrima Bunge. (BI), Ribes Uva – crispa L. (RU) and Prunus spinosa L. (PS) on soil quality indicators in Kinj region of northern Iran were investigated: 1) CM-BI-RU-PS; 2) CM-BI-RU; 3) CM-BI, and 4) pure CM. Soil samples were taken from 0 to 10 cm depth from each land cover as well as organic material (litter) and root samples. All samples were subjected to physical, chemical and biological analysis for soils and chemical analysis for litter and roots. The results showed that litter thickness under pure Crataegus (6.31 cm) was 4–53% higher than in mixed (2.95–6.05 cm) land covers. The soil fertility and biological characteristics were also lower by about 50% under the pure Crataegus than in the mixed shrublands. Based on principle component analysis (PCA), different land covers can be distinguished from each other based on litter, soil and root characteristics. In this regard, the first and second axes explained 36.86 and 16.40% of the total variance, respectively. PCA output showed that habitats with higher litter quality (i.e., higher values of N), and high soil fertility and biological activity belonged to CM-BI-RU-PS and CM-BI-RU land covers. Conversely, CM-BI and pure CM covers have poorer litter quality (i.e., higher values of C and C/N ratio) and lower levels of soil fertility indicators and biological activities. The results of this research indicate that the diversity of land cover in Crataegus ecosystems in semi-arid areas can maintain soil quality and create hotspots of soil quality indicators. Based on this, it is recommended to pay more attention to species diversity in order to restore degraded habitats in similar ecosystems, thus is important planting companion shrub species in addition to Crataegus.

Research on driving force and dynamic characteristics of pantograph–catenary arc

Pantograph–catenary (PC) system is the key current collection equipment for electrified rail vehicles. The PC arc ages the contact line and pantograph abnormally, which is a limiting factor for rail transit to increase the speed of operation. To reduce the harm caused by the PC arc, in this article, a new PC arc chain model was established, which considered the arc current element mass and the acceleration process, updating the control equations. Meanwhile, a PC arc experimental platform was built in order to verify this model. It is demonstrated that the simulation results obtained by this work fit the arc and are suitable to describe the arc in the field. Experiments have found that the evolution of PC arc can be divided into three distinct processes: arc initial process, rapid stretching process and violent oscillation process. Combined with the model, the driving force and dynamic characteristics of the PC arc root and column in each process have been studied. The electromagnetic force dominates the arc evolution in the first two processes, and then the wind load dominates the last process. Besides, thermal buoyancy dominates the arc root jumping behavior. The driving mechanism for the movement of arc has been revealed. The arc root first suppresses the arc column, and then the arc column pulls the arc root. It is helpful for controlling PC arcs in the field.

Ecological Damage Behind Ski Resorts and Feasible Governance Measures

Construction of ski resorts involves machine-grading slopes, which alters the soil's physical, chemical, and biological qualities and has a substantial long-term ecological influence on the environment. To improve slope stability and reduce the risk of natural hazards and restore the biotic and abiotic conditions of the soil, it is important to establish and develop plant communities. This study assesses changes in plant-soil characteristics and the long-term consequences of machine-grading and concurrent ski-run restoration to help create the best procedures for future ski-run development. Ski trails were surveyed for soil, vegetation and root characteristics and unaltered control sites away from the ski trails were evaluated. Plant cover on ski trails remained constant over time, but plant richness and variety significantly increased, reaching levels comparable to undisturbed vegetation. The plant mix transitioned to more semi-natural stages, exhibiting decreased planted plants and a corresponding rise in the cover of native species populating the area. Compared to unaffected locations, the root trait data showed significant differences between machine grading and vegetation’s short- and long-term effects. As a result of long-term management, the aggregate stability in the ski slopes remained lower as well as the organic content remained higher than in the undisturbed locations. Even though the soil still has a lower chemical and physical fertility than the quiet sites, the plant species composition indicates a satisfactory degree of renaturalization. The standard actions used allowed the ecosystem to recover in three decades partially.

Oriental beech roots improve soil aggregate stability and reduce soil detachment rate in forest lands

In many forestlands, such as Saravan Forest Park, the high capacity of soil detachment from deforestation and subsequent ecological restoration are important issues that need detailed information about plant and tree species for the objectives of soil conservation. To determine if some species are more helpful for the stability of soil aggregates and thus reducing soil erosion, we examined Oriental beech species, compared to three other species (Crataegus ambigue, Primula heterochroma and Rubus persicus) in the Saravan forest park, and measured how root characteristics (root biomass, root length and root weight density) influenced mean weight diameter of aggregates (MWD) and soil detachment rate (Dc). For measuring Dc, undisturbed samples collected from soils under the four studied species and subjected to five slopes (from 4.8 to 31.4%) and five water discharges (from 0.26 to 0.65 l m−1 s−1) by a hydraulic flume. Results showed that Oriental beech roots can significantly influence soil aggregate stability. MWD was greater in soil under Oriental beech species characterized by high values of root biomass, root length and root weight density. Moreover, Dc was significantly lower in soils with Oriental beech species compared to three other species. Pearson's correlation matrix showed a strong positive correlation between MWD and the root characteristics (P < 0.01) (R2 = 0.8). Also, the clustering of soils among the studied species by the principal component analysis (PCA) revealed a clear difference based on the root characteristics and MWD. Generally, this study showed that, compared with other species, the root system of Oriental beech is more effective in the stabilization of slope by the binding effect on the soil, thus improving aggregate stability and reducing soil detachment rates.

Photomorphogenesis and Photosynthetic Traits Changes in Rice Seedlings Responding to Red and Blue Light.

The purpose of this study is to determine the effects of red and blue lights on the photomorphogenesis and photosynthetic traits of rice seedlings. The rice seedlings were cultured with red light (R), blue light (B), combined red and blue lights (R3B1/R1B1/R1B3), and white light (CK) as the control. The combined application of red and blue lights could promote the growth of rice seedlings to varying degrees; enhance photosynthesis by increasing the seedling leaf area, chlorophyll content, and chlorophyll fluorescence; improve root characteristics by increasing root number, root volume, and root activity; and thus increase the dry matter accumulation of rice seedlings. In addition, the combination of red and blue lights could regulate the expression of genes related to photosynthesis in rice leaves, affect the activity of the Rubisco enzyme, and then affect the photosynthesis of rice seedlings. These results indicate that red and blue lights have direct synergistic effects, which can regulate the growth of rice seedlings and promote the morphogenesis of rice seedlings. The combined application of red and blue lights can be used to supplement the light in rice-factory seedling raising.