Root Characteristics Research Articles

Spatiotemporal Distribution of Water and Nitrogen in Border Irrigation and Its Relationship with Root Absorption Properties

The spatiotemporal distribution characteristics of water and nitrogen in the soil profile are essential influencing factors that determine the development of crop root systems. The purpose of this study was to clarify the inter-row and inter-tree variability in soil moisture in the apple root zone, and to determine the effective root diameter ranges of apple trees that influence water and nitrogen absorption. The method used was a 2-year border irrigation experiment carried out in a traditional apple orchard in Zuncun, Shanxi Province, China. Dynamic variations in the soil moisture between trees within the row (perpendicular to the direction of border irrigation) and between rows (along the direction of border irrigation) were continuously measured from 2015 to 2016, and a specific soil profile was excavated to analyze the distribution characteristics of soil water, nitrogen, and roots with different diameters. The results showed obvious variations in soil moisture in the surface soil of 0–30 cm, and the soil moisture content between rows was 5% higher than that between trees within the row. The root length density in the soil between trees within the row was 33.5% higher than that in the soil between rows. Bivariate correlation analysis showed that the correlation between the root system and nitrogen and water was ranked from highest to lowest: total nitrogen (0.741) > nitrate nitrogen (−0.36) > soil moisture (−0.273). The correlation coefficient between trees within the row was higher than that between rows. Lower soil moisture between trees within the row resulted in increased root biomass and more active uptake activity between trees within the row. There were different significant correlations between the specific root diameter and the contents of soil water and nitrogen, showing that the 1.5 mm diameter roots correlated with the water content, whereas the 2.0 mm diameter roots correlated with the nitrogen content. The findings of this study provide a deeper understanding of the absorption mechanism of crop roots for soil water and nitrogen.

Root‐associated fungi not tree density influences stand nitrogen dynamics at the larch forest–tundra ecotone

Abstract Greater tree density and forest productivity at the tundra–taiga ecotone (TTE) are expected with climate warming, with potential feedbacks to the climate system. Yet, competition for nitrogen (N) may impact TTE dynamics. Greater tree density will likely increase N demand, while reducing N supply through soil shading and slower decomposition rates. We explored whether characteristics of roots and root‐associated fungi important to N acquisition responded to changes in density at the TTE and were related to above‐ground stand productivity and N cycling. We measured rooting depth, uptake of N forms among soil layers and ectomycorrhizal (EcM) colonization and composition along a natural tree density gradient of monodominant larch Larix cajanderi in northeastern Siberia. We tested relationships between larch root and fungal characteristics, above‐ground productivity and stand‐level N cycling parameters. Overall, there was preferential uptake of ammonium compared to glycine or nitrate. Nitrogen uptake was greatest in shallow soils of the organic horizon and related to root chemistry, root‐associated fungi and above‐ground N cycling parameters, but the direction of these relationships depended on N form. Uptake of different N forms, rooting depth and EcM colonization and composition were not related to tree density, but fungal composition was correlated with root N chemistry and above‐ground N cycling parameters. In addition to EcM, the abundance of dark septate endophytes and other ascomycetous taxa was positively related to N uptake and above‐ground N cycling parameters. Synthesis. There was little impact of tree density on root and fungal parameters related to N acquisition suggesting intraspecific larch competition for N was not amplified with increased density. There was, however, a strong impact of root‐associated fungi on N uptake and stand N dynamics regardless of tree density. Together, this suggests an important role of root‐associated fungi on broadscale patterns of N cycling in TTE larch forests independent of changes in tree density expected with climate warming.

Effects of Drought on the Growth of Lespedeza davurica through the Alteration of Soil Microbial Communities and Nutrient Availability.

Lespedeza davurica (Laxm.) is highly important for reducing soil erosion and maintaining the distinctive natural scenery of semiarid grasslands in northwest China. In this study, a pot experiment was conducted to investigate the effects of drought (20% water-holding capacity) on biomass and its allocation, root characteristics, plant hormones, and soil microbial communities and nutrients after L. davurica was grown in a greenhouse. Drought reduced the total biomass of L. davurica but increased the root:shoot biomass ratio. In addition, drought altered the composition and structure of microbial communities by limiting the mobility of nutrients in non-rhizosphere soils. In particular, drought increased the relative abundances of Basidiomycota, Acidobacteria, Actinobacteria, Coprinellus, Humicola and Rubrobacter, which were closely positively related to the soil organic carbon, pH, available phosphorus, ammonia nitrogen (N) and nitrate N under drought conditions. Furthermore, soil fungi could play a more potentially significant role than that of bacteria in the response of L. davurica to drought. Consequently, our study uncovered the effects of drought on the growth of L. davurica by altering soil microbial communities and/or soil nutrients, thus providing new insights for forage production and natural grassland restoration on the Loess Plateau of China.

Evaluating the feasibility of muck from slurry shield tunnels as a growth medium for landscaping

ABSTRACT Muck from slurry shield tunnels (MSST) is a complex mixture. Directly transporting this muck to dumping grounds not only increases the costs but also raises environmental concerns due to its unusual properties. In this study, a formula has been studied that can turn the MSST into an environment friendly soil. The treatment process can realize the harmless disposal and effective utilization of MSST. In the laboratory study, three different types of growing media (MSST, MSST with 1% fly ash, and local garden soil) were used to grow ryegrass in a series of pot experiments, and the seed germination, chlorophyll content, root characteristics, root activity and physical and chemical properties of the growing media were examined. The results showed that MSST and MSSTF (MSST with added fly ash) can be used as a soil matrix for ryegrass because they exhibited a technical performance comparable to that of local garden soil (LGS), and the physicochemical parameters of the soil matrix were enhanced compared with the standard values of CJT 340–2011. Although the additive (fly ash) and different types of substrates can affect plant growth and the properties of harvested soils, the level of variation decreases with the stage of growth. As waste recycling is the primary objective of this work, MSSTF is the ideal substrate to use. The treatment process is easy to handle, and represents a sustainable option and an environmentally friendly, beneficial use of MSST.Implications: Muck discharged from slurry shield tunnel construction has put great pressure on the environment and construction cost because of a large number shield tunnels emerging in cities. Directly transporting the discharged muck waste to dumping site not only increases the machinery and labor costs but also raises environmental concerns. Therefore, we explore the way of recycling the discharged muck from slurry shield tunnel as a growth medium for landscaping which was proved to be feasible by a series of pot experimental study. Recycling the discharged muck from shield tunnel as the growth medium for landscaping instead of using purchased raw materials not only can dramatically reduce project costs but also can obviously minimizing the consequent environment pollution. Such technology can contribute to sustainable developments and cleaner construction of infrastructures.

Root characteristics and yield of rice as affected by the cultivation pattern of strong seedlings with increased planting density and reduced nitrogen application

To address the relationships between the amount of nitrogen fertilizer application and the yield of double cropping rice systems, we investigated the effects of a cultivation pattern of strong seedlings with increased planting density and reduced nitrogen application (SDN) on the morphological and physiological characteristics of double cropping rice. Our results indicated that the effects of SDN on the morphological characteristics of the single plant roots of double cropping rice were not significant, but the morphological characteristics of the population roots were largely different. Specifically, SDN significantly increased the morphological indexes of the root population such as root fresh weight, root volume, root number, root length and root dry weight. The effects of SDN on the total root absorption areas and root active absorption areas of the single plants were non-significant, but it dramatically enhanced the total root absorption areas and root active absorption areas of the plant population during the tillering, heading and mature stages. In addition, SDN significantly increased the root bleeding intensity and elevated the soluble sugar and free amino acid contents of root bleeding sap. Compared to the traditional cultivation pattern (CK), SDN significantly increased root bleeding intensity at the heading stage by 4.37 and 8.90% for early and late rice, respectively. Meanwhile, SDN profoundly enhanced the soluble sugar contents of root bleeding sap by 12.85 and 10.41% for early and late rice, respectively. In addition, SDN also significantly enhanced free amino acid content of root bleeding sap by 43.25% for early rice and by 37.50% for late rice systems compared to CK. Furthermore, SDN increased the actual yield of double cropping rice mainly due to the higher effective panicle number and the larger seed-setting rate. The actual yields of early rice under SDN were higher than CK by 9.37 and 5.98% in 2016 and 2017, and the actual yields of late rice under SDN were higher than CK by 0.20 and 1.41% in 2016 and 2017, respectively. Correlation analysis indicated that the significant positive correlations were observed between the majority of the root indexes and the actual yield across the four different growth stages.

Investigation on the arc root characteristics of vacuum arc between the iron-core cup-shaped transverse magnetic field contacts

The severity of the contact surface ablation determines the breaking capacity of the vacuum circuit breaker, and the interaction between the arc root and the electrode is the main cause of the contact surface ablation. The characteristics of the arc root determine the magnitude of the electromagnetic force received by the arc during the movement stage as well as the shape and speed of the arc movement. It will eventually affect the temperature of the contact surface and the ablation situation. This paper studied the arc root characteristics of high-current constricted vacuum arcs between the iron-core cup-shaped transverse magnetic field contacts and put forward the idea of using the ratio of cathode and anode arc root areas to quantitatively analyze the concentration of vacuum arc. The research on the arc root characteristics of the vacuum arc can help to improve the arc characteristics and arcing mechanism, and the proposition of the ratio can provide a new method for the study of constricted arc. This can provide a basis for improving the arc extinction performance of the switch, reducing the ablation of the contact material, and improving the contact life.

ROOTS CHARACTERISTICS AND EFFECTS OF CONTAINERS ON THE QUALITY OF TOONA CILIATA M. ROEMER SEEDLINGS

The objective was to evaluate the effects of recipients and root characteristics on the quality of Australian cedar seedlings. The research was carried out in two stages, the first consisted of seedling production in the nursery and evaluation of morphological parameters, and the second consisted of evaluating the potential for root regeneration. There were five treatments involving two production systems for seedlings, tubes, and plastic bags: T1 – tube (288 cm3); T2 – tube (120 cm3); T3 - tube (55 cm3); T4 - plastic bags (424 cm3); and T5 - plastic bags (216 cm3). The seeds used are from a matrix tree located at the State University of Southwest Bahia. The design of the experiment was a completely randomized design with four replications. The morphological parameters evaluated were a) shoot height (H); b) neck diameter (D); c) fresh and dry biomass of shoots and roots; d) H/D, H/SDM, and shoot and root dry mass ratio (SDM/RDM); e) Dickson Quality Index (DQI), and f) the total number of regenerated roots present in the upper and lower parts of each container. The results showed that the tubes with 288 cm³ of volumetric capacity produced seedlings with higher averages for the morphological and root characteristics, constituting the ideal production system for Australian cedar seedlings. In the absence of tubes with 288 cm³, it is possible to use plastic bags (424 cm³) for this species. The evaluated root regeneration potential proves to be a favorable prognosis of rapid establishment and performance of seedlings in the field.

Genus Decalepis: Biology, Importance and Biotechnological Interventions

The steno-endemic species from the genus Decalepis are facing a high level of threat due to destructive wild harvesting. The genus claimed its paramount importance to mankind due to its unique tuberous root characteristics and exhibits a wide range of biological and medicinal properties, and is used in pharmaceutical and food industries. Plants of this genus are endemic to limited areas of peninsular India, such as the Eastern and Western Ghats, and according to the International Union for Conservation of Nature (IUCN), species from the genus Decalepis are considered globally critically endangered. The genus comprises of five species namely Decalepis hamiltonii Wight & Arn., Decalepis arayalpathra (J. Joseph & V. Chandras.) Venter, Decalepis salicifolia (Bedd. ex Hook. f.) Venter, Decalepis nervosa (Wight & Arn.) Venter, and D. khasiana (Kurz) Ionta ex Kambale. All the species of the genus Decalepis are being used by the tribal people and also in traditional Indian and Chinese medicine. International trade for this plant is also increasing, resulting in overharvesting. The traditional method of propagation, viz., seed germination and vegetative, are limited and jeopardizes the species population, whereas plant tissue culture provides the opportunity for extensive production of the plant in vitro without sacrificing their natural habitats. This review is aimed to systematize the up-to-date facts related to the Genus Decalepis with the exploration of their geographic distribution, chemical profile, pharmacology, biological activities, micropropagation, somatic embryogenesis, synthetic seed, and genetic transformation.

Effects of a soil collembolan on the growth and metal uptake of a hyperaccumulator: Modification of root morphology and the expression of plant defense genes

Soil collembolans live in close proximity to plant roots and may have a role in the phytoextraction of potentially toxic metals from contaminated soils but the underlying mechanisms remain poorly investigated. We hypothesize that soil collembolans may change the root morphology of hyperaccumulators by regulating plant physiological characteristics. Here, a pot experiment was conducted in which a cadmium (Cd) and zinc (Zn) hyperaccumulator (Sedum plumbizincicola) was grown with or without a collembolan (Folsomia candida), and plant transcriptome and hormones as well as the root characteristics of S. plumbizincicola were analyzed. F. candida promoted the growth and Cd/Zn uptake of S. plumbizincicola, the root and shoot biomass increasing by 53.3 and 34.4%, and the uptake of Cd and Zn in roots increased by 83.2 and 65.4%, respectively. Plant root morphology, total root length, root tip number and lateral root number increased significantly by 40.7, 37.2 and 33.8%, respectively, with the addition of F. candida. Transcriptome analysis reveals that the expression levels of defense-related genes in S. plumbizincicola were significantly up-regulated. In addition, the defensive plant hormones, i.e. salicylic acid in the roots, increased significantly by 338%. These results suggest that the plant in defense of the action of F. candida regulated the expression of the corresponding genes and increased the defensive plant hormones, thus modifying root morphology and plant performance. Overall, this study highlights the importance of the regulation by collembolans of plant growth and metal uptake by interaction with hyperaccumulator roots.

Drag force coefficient of the flexible vegetation root in an artificial floating bed channel

As the artificial floating bed (AFB) is more extensively applied in water treatment, the hydraulic characteristics of the AFB has been broadly investigated. However, the conventional studies on the hydraulic characteristics exhibited by the AFB tends to rigid vegetation roots, whereas the research on flexible vegetation roots is relatively less. In this study, three different characteristics of the flexible vegetation root on the AFB experiment were conducted in different hydraulic conditions to study the effect of flexible root system on the hydraulic characteristics. At the same time, the formula of drag force coefficient is obtained by combining theoretical analysis and machine learning. The main results are as follows: (1) The more fibrous roots in same root area station on the AFB, the smaller the root resistance of the AFB; (2) The drag force coefficient CDx of flexible vegetation roots decreases with the increase of Reh; (3) The best root coefficient for describing root characteristics is characteristic diameter d50.

Left ventricular stroke volume calculation based on Reuleaux triangle formula: correct geometric characteristics of aortic root in systemic blood flow assessment

Left ventricular stroke volume calculation based on Reuleaux triangle formula: correct geometric characteristics of aortic root in systemic blood flow assessment

Freeze\u2013thaw cycle frequency affects root growth of alpine meadow through changing soil moisture and nutrients

Alpine meadows grow in alpine regions and play an important role in the production and life of alpine regions. As a unique feature of alpine regions, freeze–thaw cycles (FTCs) affect the growth of alpine meadows. However, with climate change, the change in the freeze–thaw cycle frequency (FTCF) has become obvious. These changes affect the content and distribution of soil moisture and nutrients, as well as the growth of roots in the alpine meadow. Therefore, based on the analysis of FTCF in the Nagqu River Basin, the characteristics of soil moisture, nutrients, and alpine meadow roots are analyzed, thus revealing the influence mechanism of FTCF on the root growth of alpine meadows. The results highlight three major findings. (1) Compared with the low-frequency mode (LFM), the moisture at 0–20, 20–40, and 40–60 cm in the high-frequency mode (HFM) has decreased by 30.74%, 52.89%, and 47.52%, respectively. Additionally, in HFM the contents of soil hydrolysable nitrogen (HN), available K (AK), and microbial biomass carbon (MBC) at the same depth are lower than those in LFM. (2) The original distribution of soil moisture at 0–60 cm has gradually increased from the surface to the bottom. However, with the increase in FTCF, the distribution of the soil moisture now means that the soil moisture at the surface (0–20 cm) and the deeper layers (40–60 cm) is higher than that in the middle (20–40 cm). (3) With the increase in FTCF, the growth mode of alpine meadow roots has changed from vertical extension to horizontal divergence; the distribution range of roots has changed from 0–40 cm to 0–20 cm; the length, surface area, and volume of 0–0.5 mm roots have increased by 20.95 cm, 1.90 cm2, and 0.014 cm3; and the corresponding specific gravity has increased by 9.09%, 13.50%, and 12.14%, respectively. This study provides a theoretical basis for predicting the growth mode of alpine meadow roots in the Nagqu River Basin under the influence of climate change and provides guidance for protecting the ecology of alpine regions and mitigating and solving global climate change.

The establishment of winter wheat root system architecture in field soils: The effect of soil type on root development in a temperate climate.

Winter wheat (Triticum aestivum L.) is an important cereal crop in the temperate climates of western Europe. Root system architecture is a significant contributor to resource capture and plant resilience. However, the impact of soil type on root system architecture (RSA) in field structured soils is yet to be fully assessed. This work studied the development of root growth using deep cultivation (250mm) during the tillering phase stage (Zadock stage 25) of winter wheat across three soil types. The three sites of contrasting soil types covered a geographical area in the UK and Ireland in October 2018. Root samples were analysed using two methods: X-ray computed tomography (CT) which provides 3D images of the undisturbed roots in the soil, and a WinRHIZO™ scanner used to generate 2D images of washed roots and to measure further root parameters. Important negative relationships existed between soil bulk density and root properties (root length density, root volume, surface area and length) across the three sites. The results revealed that despite reduced root growth, the clay (Southoe) site had a significantly higher crop yield irrespective of root depth. The loamy sand (Harper Adams) site had significantly higher root volume, surface area and root length density compared with the other sites. However, a reduction in grain yield of 2.42Mt ha-1 was incurred compared with the clay site and 1.6Mt ha-1 compared with the clay loam site. The significantly higher rooting characteristics found in the loamy sand site were a result of the significantly lower soil bulk density compared with the other two sites. The loamy sand site had a lower soil bulk density, but no significant difference in macroporosity between sites (p>0.05). This suggests that soil type and structure directly influence crop yield to greater extent than root parameters, but the interactions between both need simultaneous assessment in field sites.

How Does Chinese Outward Foreign Direct Investment Respond to Host Country Cultural Tolerance and Trust?

Based on 2010 to 2019 Chinese outward foreign direct investment (OFDI) panel data from 39 host countries, this paper studies the relationships between host country cultural characteristics and Chinese OFDI. The OLS regression results show that the cultural tolerance and trust in the host countries are significantly positively correlated with Chinese OFDI, which are robust according to the system GMM tests. Further analysis reveals that cultural tolerance is more positively related to Chinese OFDI in host countries with higher legislation and economic freedom, while cultural trust is positively associated with Chinese OFDI in host countries with lower legislation and economic freedom. In addition, higher cultural tolerance and trust promote Chinese OFDI in countries with greater cultural distance. Unlike traditional studies based on cultural distance in international trade, using more representative cultural characteristics, this paper provides references to Chinese OFDI decision-making based on the root characteristics associated with heterogeneous cultural influences.

Improving Soil Resource Uptake by Plants Through Capitalizing on Synergies Between Root Architecture and Anatomy and Root-Associated Microorganisms.

Root architectural and anatomical phenotypes are highly diverse. Specific root phenotypes can be associated with better plant growth under low nutrient and water availability. Therefore, root ideotypes have been proposed as breeding targets for more stress-resilient and resource-efficient crops. For example, root phenotypes that correspond to the Topsoil Foraging ideotype are associated with better plant growth under suboptimal phosphorus availability, and root phenotypes that correspond to the Steep, Cheap and Deep ideotype are linked to better performance under suboptimal availability of nitrogen and water. We propose that natural variation in root phenotypes translates into a diversity of different niches for microbial associations in the rhizosphere, rhizoplane and root cortex, and that microbial traits could have synergistic effects with the beneficial effect of specific root phenotypes. Oxygen and water content, carbon rhizodeposition, nutrient availability, and root surface area are all factors that are modified by root anatomy and architecture and determine the structure and function of the associated microbial communities. Recent research results indicate that root characteristics that may modify microbial communities associated with maize include aerenchyma, rooting angle, root hairs, and lateral root branching density. Therefore, the selection of root phenotypes linked to better plant growth under specific edaphic conditions should be accompanied by investigating and selecting microbial partners better adapted to each set of conditions created by the corresponding root phenotype. Microbial traits such as nitrogen transformation, phosphorus solubilization, and water retention could have synergistic effects when correctly matched with promising plant root ideotypes for improved nutrient and water capture. We propose that elucidation of the interactive effects of root phenotypes and microbial functions on plant nutrient and water uptake offers new opportunities to increase crop yields and agroecosystem sustainability.

Influence of Super Absorbent Polymer on Root Characteristics and Anchorage of Amorpha fruticosa on Rocky Slope

Super absorbent polymer (SAP), known as a water retention agent, has a high capacity for water absorption, which can help enhance the soil structure. This paper studied the effects of SAP dosages on the root characteristics and anchorage of Amorpha fruticosa on rock slopes. The internal relationship between root growth effect and soil was discussed, and a specific reference was provided for the rational application of SAP on slopes. Using the pull-out and tensile resistance tests, we systematically studied the changes of soil properties, root distribution, root tensile strength, and root anchorage under six different SAP dosages. The results indicated that: (1) With the increase in SAP dosage, the natural soil water content and water content after 24 h of watering increased significantly, whereas the contents of TN, TP, and TK decreased dramatically. (2) With the increase in SAP dosage, the amount and length of first-order and secondary lateral roots decreased significantly, and there was no significant difference in diameter. The amount of downslope first-order and unembedded secondary lateral roots is greater than upslope. The amount of upslope embedded secondary lateral roots is greater than in downslope. (3) Tensile strength: embedded secondary root > non-embedded secondary root > first-order lateral root; upslope root > downslope root. (4) With the increase in SAP dosage, the plant anchorage drops noticeably. This study concluded that the significant addition of SAP could enhance the tensile strength of upslope embedded secondary lateral roots but would adversely affect soil nutrients, root distribution, and root anchorage. The addition of SAP in this test had no significant effect on improving slope stability. From the perspective of reinforcement capacity, we cannot blindly pursue the survival rate and other high dosage use of water retention agents to increase the risk of slope destabilization.

Effects of root characteristics on panicle formation in japonica rice under low temperature water stress at the reproductive stage

Cold stress during the reproductive stage causes spikelet sterility and limits rice productivity in high-altitude and high-latitude regions. In higher plants, phytohormones regulate root and panicle development under environmental stress. Maintaining high root physiological activity during the reproductive stage may be a strategy for high yields in crops under abiotic stress. However, little is known about the root physiological activity and panicle size response mechanisms associated with rice cold tolerance at the reproductive stage. In this study, we investigated the effects of low root zone water temperature (Tw) during reproductive growth on root physiological characteristics and root phytohormones associated with panicle development in japonica rice from 2018 to 2019. The rice plants were subjected to 17 °C low Tw for 5, 10, and 15 days during reproductive growth. The results showed that, compared with the control, rice pollen grain development was hindered, and the percentage of fertile pollen decreased under low Tw; the number of surviving total panicle branches decreased significantly; the number of degraded branches increased significantly; the range of change increased gradually with the extension of low Tw stress time; and the impact of low Tw stress on the secondary branches and spikelets was greater than on the primary branches and spikelets. The abundance of zeatin (ZR) and auxin (IAA) in the roots, the root physiological activity, and the number of surviving spikelets and branches had a significant positive correlation in variety DN428. DN428 exhibited strong cold tolerance and possessed a high level of ZR and IAA in the roots, which allowed it to maintain root antioxidant enzyme activity, root vitality, and the root absorption surface area at a relatively stable level, resulting in the roots not accumulating large amounts of soluble protein, soluble sugar, malondialdehyde, and proline. This facilitated the accumulation and transfer of photosynthetic materials above the ground and provided a stable material foundation for spikelet and branch formation.

Overexpression of the vacuolar sugar importer BvTST1 from sugar beet in Camelina improves seed properties and leads to altered root characteristics.

Overexpression of the vacuolar sugar transporter TST1 in Arabidopsis leads to higher seed lipid levels and higher total seed yield per plant. However, effects on fruit biomass have not been observed in crop plants like melon, strawberry, cotton, apple, or tomato with increased tonoplast sugar transporter (TST) activity. Thus, it was unclear whether overexpression of TST in selected crops might lead to increased fruit yield, as observed in Arabidopsis. Here, we report that constitutive overexpression of TST1 from sugar beet in the important crop species Camelina sativa (false flax) resembles the seed characteristics observed for Arabidopsis upon increased TST activity. These effects go along with a stimulation of sugar export from source leaves and not only provoke optimised seed properties like higher lipid levels and increased overall seed yield per plant, but also modify the root architecture of BvTST1 overexpressing Camelina lines. Such mutants grew longer primary roots and showed an increased number of lateral roots, especially when developed under conditions of limited water supply. These changes in root properties result in a stabilisation of total seed yield under drought conditions. In summary, we demonstrate that increased vacuolar TST activity may lead to optimised yield of an oil-seed crop species with high levels of healthy ω3 fatty acids in storage lipids. Moreover, since BvTST1 overexpressing Camelina mutants, in addition, exhibit optimised yield under limited water availability, we might devise a strategy to create crops with improved tolerance against drought, representing one of the most challenging environmental cues today and in future.

Responses of Fine Roots at Different Soil Depths to Different Thinning Intensities in a Secondary Forest in the Qinling Mountains, China.

Simple SummaryFine roots of different sizes make critical contributions to carbon stocks and terrestrial productivity, but the changed characteristics of fine roots with different diameters at different soil depths under thinning disturbances remain poorly understood. In our study, we aimed to elucidate the response characteristics of fine roots with different diameters to thinning intensities at different soil depths, and to explore the driving mechanism of the change in the fine-root characteristics. We found that higher thinning intensities negatively affected 0.5–1 mm and 1–2 mm fine-root biomass, while the <0.5 mm fine-root characteristics fluctuated with increasing thinning intensities. Our results suggest that the thinning intensity exhibits varied influential mechanisms on the changed characteristics of <0.5 mm fine roots and thicker fine roots (0.5–2 mm). Collectively, our findings provide important insights into the effects of forest management on changes in fine-root characteristics, and supplement meaningful data on fine-root productivity to improve the parameterization of future ecological models.Fine roots make critical contributions to carbon stocks and terrestrial productivity, and fine roots with different diameters exhibit functional heterogeneity. However, the changed characteristics of fine roots with different diameters at different soil depths following thinning disturbances are poorly understood. We investigated the biomass, production, mortality and turnover rate of <0.5 mm, 0.5–1 mm, and 1–2 mm fine roots at 0–20 cm, 20–40 cm, and 40–60 cm soil depths under five thinning intensities (0%, 15%, 30%, 45%, and 60%) in a secondary forest in the Qinling Mountains. The biomass, production and turnover rate of <0.5 mm fine roots fluctuated with increasing thinning intensities, while the 0.5–1 mm and 1–2 mm fine-root biomass significantly decreased. The thinning intensities had no effects on the fine-root necromass or mortality. The change in the fine-root characteristics in deeper soils was more sensitive to the thinning intensities. The principal component analysis results showed that increased <0.5 mm fine-root biomass and production resulted from increased shrub and herb diversity and biomass and decreased soil nutrient availability, stand volume, and litter biomass, whereas the 0.5–1 mm and 1–2 mm fine-root biomass showed the opposite trends and changes. Our results suggest that different thinning intensities exhibit varied influential mechanisms on the changed characteristics of fine roots with different diameters.

Deep root information “hidden in the dark”: A case study on the 21-m soil profile of Robinia pseudoacacia in the critical zone of the Chinese loess Plateau

Deep roots can uptake deep soil water to support plant growth and mitigate climate change in water-limited ecosystems. Few studies have been conducted on the deep root characteristics in the soil profile as limited field data are available. To explore the relationship between the deep root characteristics, depth, and soil water status, we obtained the distribution pattern of deep roots and soil water content along a 21-m soil profile (n = 22) in a mature Robinia pseudoacacia plantation. The maximum rooting depth, mean root biomass, and mean depths corresponding to 50% and 90% of the total root biomass of 17-year-old R. pseudoacacia trees were >20 m, 0.083 ± 0.029 g·cm−2, 1.17 ± 1.74, and 6.15 ± 3.98 m, respectively. We established an exponential power model to fit the relationship between the deep root biomass and soil depth, which had a higher goodness-of-fit than the typical exponential model, logistic model, and piecewise linear model. The root morphological characteristics along the 21-m vertical profile rapidly decreased with depth in the 0–1-m layer, and then stabilized, while the specific root length (SRL) and specific root area (SRA) increased with depth. The relationships between the SRL, SRA, and soil water content in the dried soil layers with roots (SWC-DSL) were significantly positive (both p < 0.01), while those between average root diameter density and SWC-DSL were significantly negative (p < 0.001), suggesting that roots increased their length rather than diameter to acquire water resources with relatively low carbon investment. The soil depth and soil water availability co-controlled root biomass and root morphological characteristics. Our findings highlight the importance and complexity of deep roots and their morphological characteristics, which are fundamental for forest models and management to maintain sustainable development between soil water and root water uptake.