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Plant taxa and traits do not necessarily show synchronous responses to ecological disturbance. Based on the observation that taxonomically over‐diversified communities might be phenotypically redundant, we speculated that taxonomic and phenotypic community reassembly might be decoupled after fire in Mediterranean ecosystems.We applied a multi‐trait approach to describe plant community re‐assembly after fire across three 20‐year chronosequences based on 117 species and 23 traits, including whole‐plant, above‐ground and below‐ground traits. We quantified the post‐fire trajectories of different plant traits by analysing their community‐weighted means individually. We estimated the short‐ and long‐term phenotypic diversity of burned plots based on sets of traits. We also tested if trait and species turnover are decoupled across post‐fire trajectories. Finally, we calculated phenotypic redundancy, and assessed if above‐ and below‐ground traits have contrasted responses during post‐fire community reassembly.Individually, 16 out of 23 traits were affected by fire in the short term. Plant phenotypic diversity (stdMPD) decreased immediately after fire, driven by changes in whole‐ and above‐ground traits. Both whole‐ and above‐ground stdMPD in burned plots described positive trajectories across the chronosequences tending to converge with long‐unburned plots, whereas below‐ground stdMPD remained unaltered through time.Taxonomic and phenotypic beta diversity showed decoupled trajectories due to a larger species than trait replacement across time since fire. Finally, overall phenotypic redundancy of the studied plant communities described a regressive trajectory, similarly to above‐ground traits, whereas root traits kept a steady phenotypic redundancy through time.Synthesis. We provide evidence that above‐ and below‐ground traits describe different recovery trajectories after fire, with significant effects on the phenotypic redundancy of plant communities. Our results encourage the use of multi‐trait approaches to understand how the plant reassembly operates after disturbance, in order to refine ecological theory. This strategy might improve the efficacy of restoration programs through a functional approach to species selection. [ABSTRACT FROM AUTHOR]

Plant roots employ diverse strategies to acquire soil nutrients, including direct nutrient uptake through absorptive fine roots and root hairs, scavenging nutrients by forming symbioses with mycorrhizal fungi, and mining nutrients by releasing root exudates. However, whether these three strategies are differently coordinated among phylogenetically closely related tree species and how this coordination shifts with stand development remains largely unclear.To fill these knowledge gaps, we measured 13 root morphological, architectural, physiological and mycorrhizal traits tightly related to nutrient‐acquisition of three Pinus species (P. sylvestris var. mongolica, P. densiflora and P. tabuliformis) at young (20‐year‐old) and mature (50‐year‐old) stages planted in nutrient‐impoverished sandy soils, in Northeast China.We found that young trees had thinner absorptive fine roots and a higher specific root length than mature trees across three Pinus species, indicating that roots become morphologically less efficient in 'do it yourself' scavenging nutrients during stand development. Moreover, young stands had greater root length density and root area index, and mature stands had faster root‐exudation rates, suggesting that young stands rely more on expanding soil volumes to scavenge nutrients and mature stands depend more on root exudation to 'mine' nutrients. The three Pinus species exhibited different nutrient‐acquisition strategies at the mature stage; P. densiflora had higher root length density and root area index, and the other two Pinus species had greater ectomycorrhizal colonization rates.Synthesis. Our findings highlight that phylogenetically closely related tree species may exhibit different nutrient‐acquisition strategies and suggest a shift from an extensive nutrient‐acquisition mode depending more on absorptive fine roots to an intensive nutrient‐acquisition mode relying more on root exudation during stand development. [ABSTRACT FROM AUTHOR]

This study assessed the influence of exogenous ME in the mitigation of cold damage in pepper seedlings. Melatonin (ME) is a dynamic molecule that helps plants cope with stress in several ways. Cold stress (CS) is one of the most important environmental factors that restrict plant growth and yield. Pepper (Capsicum annuum L.) is a valuable commercial crop, highly sensitive to CS. Thus, identifying an efficient strategy to mitigate cold damage is critical for long-term pepper production. For this purpose, the roots of pepper seedlings were pretreated with ME (5 mmol $ L-1) and exposed to CS for 7 d. The results indicated that CS suppressed pepper growth, hampered photosynthetic capacity, and damaged root architecture in pepper plants. In contrast, the production of reactive oxygen species (ROS), malondialdehyde (MDA), electrolyte leakage (EL), proline, and soluble sugars were enhanced in plants under CS. ME (5 mmol $ L-1) pretreatment reduced the negative effects of CS by recovering plant growth, root traits, gas exchange elements, and pigment molecules compared to CS control treatment. Furthermore, ME application efficiently reduced oxidative stress markers [hydrogen peroxide (H2O2), superoxide ion (O2 $e), EL, and MDA] while increasing proline and soluble sugar content in pepper leaves. ME application combined with CS further increased antioxidant enzymes and related gene expression. Collectively, our results confirmed the mitigating potential of ME supplementation for CS by maintaining pepper seedling growth, improving the photosynthesis apparatus, regulating pigments, and osmolyte content. [ABSTRACT FROM AUTHOR]

Salt spray is a major environmental issue in coastal areas. Cinnamomum camphora is an economically important tree species that grows in the coastal areas of southern China. Arbuscular mycorrhizal fungi (AMF) can alleviate the detrimental effects of abiotic stress on host plants. However, the mechanism by which AMF mitigates the adverse effects of salt spray on C. camphora remains unclear. A pot experiment was conducted in a greenhouse, where C. camphora seedlings were exposed to four AMF regimes (inoculation with sterilized fungi, with Glomus tortuosum, Funneliformis mosseae, either alone or in combination) and three salt spray regimes (applied with distilled water, 7, and 14 mg NaCl cm−2) in order to investigate the influence on root functional traits and plant growth. The results showed that higher salt spray significantly decreased the K+ uptake, K+/Na+ ratio, N/P ratio, total dry weight, and salinity tolerance of non-mycorrhizal plants by 37.9%, 71%, 27.4%, 12.7%, and 221.3%, respectively, when compared with control plants grown under non-salinity conditions. Mycorrhizal inoculation, particularly with a combination of G. tortuosum and F. mosseae, greatly improved the P uptake, total dry weight, and salinity tolerance of plants grown under higher salt spray conditions by 51.0%, 36.7%, and 130.9%, respectively, when compared with their counterparts. The results show that AMF can alleviate the detrimental effects of salt spray on C. camphora seedlings. Moreover, an enhanced uptake of K+ and P accounted for the resistance of the plants to salt spray. Therefore, pre-inoculation with a combination of G. tortuosum and F. mosseae to improve nutrient acquisition is a potential method of protecting C. camphora plants against salt spray stress in coastal areas. [ABSTRACT FROM AUTHOR]

Simple Summary: Barnyard grass (Echinochloa spp.) is one of the most dominant and noxious weed species in rice paddies. However, allelopathic rice is known to interfere with the growth of barnyard grass through allelochemical-mediated root interactions. Here, the allelopathic rice cultivar, "PI312777" (PI), and the non-allelopathic rice cultivar, "Lemont" (LE), were used as the materials for analysis and were subjected to the stresses of quinclorac-resistant (R) and -susceptible (S) barnyard grass, respectively. We first investigated changes in the morphological traits of the roots of two rice cultivars. Meanwhile, the levels of different plant hormones, including auxin, abscisic acid, jasmonic acid, and salicylic acid, known for their diverse adaptation strategies to biotic stress, were analyzed. The results indicated that PI demonstrated the greater competitive ability, compared to LE, under barnyard grass-induced stress, with respect to shoot and root biomass, the number of root tips, and root tip length in rice with root diameters of <0.5 mm. Salicylic acid (SA) and jasmonic acid (JA) were found to have the potential to suppress barnyard grass growth in allelopathic rice. The amounts of SA and JA demonstrated a significant correlation with the number of root tips and root tip length in rice with root diameters of <0.5 mm. Our research may aid in the development of strategies for reducing the environmental impact of herbicides through the prudent selection of non-chemical control tactics. Despite the growing knowledge concerning allelopathic interference with barnyard grass, little is understood regarding the competitive physiological mechanisms of the interaction between allelopathic rice and herbicide-resistant barnyard grass. A hydroponic system was employed to investigate the root morphological traits and different phytohormonal changes in allelopathic and non-allelopathic rice cultivars when co-planted with quinclorac-resistant and -susceptible barnyard grass, respectively. The results show that shoot and root biomass were greater in PI. Barnyard grass stress induced an increase in shoot and root biomass in PI at 7 and 14 days of co-culturing rice and barnyard grass. Especially under the stress of quinclorac-resistant barnyard grass, the shoot biomass of PI increased by 23% and 68%, respectively, and the root biomass increased by 37% and 34%, respectively. In terms of root morphology, PI exhibited a significantly higher fine-root length, in root diameters of <0.5 mm, a greater number of root tips, and longer root tips compared to LE. The response to quinclorac-resistant barnyard grass stress was consistent in terms of the SA and JA content. The obvious accumulation of SA and JA was observed in two rice cultivars under quinclorac-resistant barnyard grass stress, with greater amounts of SA and JA in PI. The significant decrease in auxin (IAA) and abscisic acid (ABA) content in rice was detected from 7 to 14 days under co-culture stress. Additionally, highly significant and positive correlations were found between SA and JA content, and the number of root tips and root tip length at root diameters of 0–0.5 mm in rice. [ABSTRACT FROM AUTHOR]

Aims: Interactions among plant species play an essential role in the establishment and performance of intercropped forest plantations and depend on the characteristics of the intercropped species and environmental conditions. Although much is known about interspecific interactions, how light conditions modulate these interactions remains unknown. Methods: In this study, we explored the effects of light intensity (shade or full light) on plant-plant interactions through a controlled pot experiment involving two local companion tree species (Phoebe chekiangensis and Torreya grandis) and Phyllostachys edulis in different planting patterns (monoculture or intercropping). Results: The effect of interspecific interaction on plant performance depended on light intensity and species. Under full light, heterogeneous neighboring plants tended to increase the nitrogen concentration in shoots and roots of the three species, while the total biomass and root-shoot mass ratio also increased for P. edulis and P. chekiangensis. Under shade conditions, all monocultures adapted to low light through a series of changes (increase in specific leaf area and chlorophyll concentration, or decrease of root-shoot ratios), while these adaptive strategies were limited in P. chekiangensis and T. grandis intercropped with P. edulis. And the performance of T. grandis was less influenced by P. edulis than by P. chekiangensis due to differences in root attributes. Conclusion: Under shade condition, P. edulis may inhibit the nitrogen acquisition of the two companion species through the plasticity advantage of root morphology and physiology traits, thus limiting their aboveground adaptive capacity to low light. [ABSTRACT FROM AUTHOR]

Summary: A key trait conferring flood tolerance is the ability to grow adventitious roots as a response to submergence. The genetic traits of deepwater rice determining the development and characteristics of aquatic adventitious roots (AAR) had not been evaluated.We used near‐isogenic lines introgressed to test the hypothesis that the impressive shoot elongation ability of deepwater rice linked to quantitative trait loci 1 and 12 also promote the development of AAR.The deepwater rice genotype NIL‐12 possessed expanded regions at the stem nodes where numerous AAR developed as a response to submergence. Two types (AR1 and AR2) of roots with distinct timing of emergence and large differences in morphological and anatomical traits formed within 3 (AR1) to 7 (AR2) d of submergence. The mechanical impedance provided by the leaf sheath caused AR2 to emerge later promoting thicker roots, higher elongation capacity and higher desiccation tolerance. Upregulation of key genes suggests a joint contribution in activating the meristem in AAR enhancing the development of these in response to submergence.The morphological and anatomical traits suggested that AR2 is better adapted to long‐term flooding than AR1. We therefore propose that AR2 in deepwater rice functions as an evolutionary defence strategy to tackle periodic submergence. See also the Commentary on this article by Maric & Hartman, 238: 1337–1339. [ABSTRACT FROM AUTHOR]

Root system architecture is important for common bean (Phaseolus vulgaris) adaptability to diverse environments. Beans employ complex adaptive root mechanisms for coping with multiple stresses in production environments. Understanding genetic control of root traits is central to improvement of common bean for adaptation to marginal environments. The objectives of this study were to (i) determine combining ability of root and agronomic traits and (ii) estimate the heritability and genetic correlation of root and agronomic traits in common bean. Four bean lines with superior root traits were crossed with four locally adapted varieties in a North Carolina II mating scheme to generate 16 crosses. The 16 F1s were selfed and advanced to F2 generation. Eight parents and their F2 progenies were evaluated in an alpha‐Lattice design with two replications. General and specific combing ability mean squares were significant (p ≤.05) for all traits measured. General predictability ratios ranged from.47 to.68 across locations suggesting that both additive and non‐additive gene action modulate root traits and seed yield. Positive and significant (p ≤.05) phenotypic and genetic correlations revealed significant association between root traits and yield. Moderate to high heritability estimates of between.43 and.67 were realized. Such estimates point to possible deployment of a successful selection programme. Genotype AFR398 displayed significant positive GCA effects among its crosses for both root and agronomic traits hence a potential candidate genotype for inclusion in a bean genetic improvement programme for marginal environments. [ABSTRACT FROM AUTHOR]

Soybean [Glycine max (L.) Merr.], an important oilseed crop, is a low-cost source of protein and oil. In Southeast Asia and Africa, soybeans are widely cultivated for use as traditional food and feed and industrial purposes. Given the ongoing changes in global climate, developing crops that are resistant to climatic extremes and produce viable yields under predicted climatic conditions will be essential in the coming decades. To develop such crops, it will be necessary to gain a thorough understanding of the genetic basis of agronomic and plant root traits. As plant roots generally lie beneath the soil surface, detailed observations and phenotyping throughout plant development present several challenges, and thus the associated traits have tended to be ignored in genomics studies. In this study, we phenotyped 357 soybean landraces at the early vegetative (V2) growth stages and used a 180 K single-nucleotide polymorphism (SNP) soybean array in a genome-wide association study (GWAS) conducted to determine the phenotypic relationships among root traits, elucidate the genetic bases, and identify significant SNPs associated with root trait-controlling genomic regions/loci. A total of 112 significant SNP loci/regions were detected for seven root traits, and we identified 55 putative candidate genes considered to be the most promising. Our findings in this study indicate that a combined approach based on SNP array and GWAS analyses can be applied to unravel the genetic basis of complex root traits in soybean, and may provide an alternative high-resolution marker strategy to traditional bi-parental mapping. In addition, the identified SNPs, candidate genes, and diverse variations in the root traits of soybean landraces will serve as a valuable basis for further application in genetic studies and the breeding of climate-resilient soybeans characterized by improved root traits. [ABSTRACT FROM AUTHOR]

It is well known that roots play a significant role in reducing water erosion in soil, yet few studies have reported the influence of crop roots on soil translocation induced by tillage in sloping fields. To examine the relationship between soil-root complexes (i.e., complexes of wheat roots and soil) and soil redistribution caused by tillage, a series of tillage experiments were carried out on bare soil and areas of wheat sown by drilling (DS) and nesting (NS) using nine slopes with gradients varying from 0.19 to 0.32 m m−1. The magnetic tracing technique was used to determine soil translocation rates under hoeing tillage in sloping landscapes in response to soil-root complexes and bare soil. The results indicated that mean displacement distance for DS and NS in the downslope direction was 0.15 m and 0.16 m, respectively. This was much shorter than that of bare soil which was 0.26 m. Mean tillage erosion rates ranged from 14.58 to 19.15 Mg ha−1 per tillage pass for DS and 13.90 –21.10 Mg ha−1 per tillage pass for NS , while reached 31.23–36.31 Mg ha−1 per tillage pass for bare soil. Tillage transport coefficients (k 3 and k 4) were 6.31 and 106.46 kg m−1 per tillage pass for DS , 6.58 and 118.68 kg m−1 per tillage pass for NS , and 28.12 and 151.07 kg m−1 per tillage pass for bare soil, respectively. A significant difference in cohesive force (C) was found between DS (NS) and bare soil (P < 0.05), thereby resulting in an increase in the soil shear strength of soil-root complexes. Compared with those of bare soil, the soil fractal dimension of soil-root complexes decreased significantly due to an increase in the percentage of coarse clods (>100 and 100–80 mm) and a decrease in the percentage of fine clods (50–20 and < 20 mm). Mean soil displacement distance caused by tillage displayed a negative relationship with C and wheat root traits (the root density, the root length density, and the root area ratio) within the hilly landscape of soil-root complexes (P < 0.05), implying that wheat roots played a crucial part in soil translocation and soil fragmentation during hoeing tillage. Our study revealed that soil-root complexes markedly reduce the soil downslope transfer process during tillage and prevent the break-up of large clods by tillage implements on sloping farmland. • Wheat root attenuated the mechanical breakage of clods during tillage operation. • Root systems increase soil shear strength and reduce fragmentation of soil clods. • Displacement distance for soil-root complexes was smaller than that for bare soil. • Tillage erosion decreased with increasing structure stability and cohesive force. [ABSTRACT FROM AUTHOR]

Background: Arbuscular mycorrhizal (AM) fungi and roots play important roles in plant nutrient acquisition, especially in nutrient poor and heterogeneous soils. However, whether an accumulation strategy of AM fungi and root exists in such soils of karst shrubland ecosystems remains unclear. Root traits related to nutrient acquisition (root biomass, AM colonisation, root acid phosphatase activity and N2 fixation) were measured in two N2-fixing plants (i.e. Albizia odoratissima (Linn. f.) Benth. and Cajanus cajan (Linn.) Millsp.) that were grown in heterogeneous or homogeneous nutrient (ammonium) soil with and without AM fungi inoculation. Results: Both of these plants had higher AM colonisation, root biomass and relative growth rate (RGR), but lower N2 fixation and root acid phosphatase activity in the rhizosphere in the heterogeneous soil environment, than that in the homogeneous soil environment. Plants grown in the AM fungi-inoculated heterogeneous soil environment had increased root biomass and root acid phosphatase activity compared with those grown in soil without inoculation. AM colonisation was negatively correlated with the N2 fixation rate of A. odoratissima, while it was not significantly correlated with the root phosphatase activity. Conclusions: Our results indicated that enhanced AM symbiosis and root biomass increased the absorptive surfaces for nutrient acquisition, highlighting the accumulation strategies of AM and root traits for plant nutrient acquisition in nutrient poor and heterogeneous soils of the karst shrubland ecosystem. [ABSTRACT FROM AUTHOR]

Summary: Mangroves are among the world's most carbon‐dense ecosystems, but have suffered extensive deforestation, prompting reforestation projects. The effects of mangrove reforestation on belowground carbon dynamics are poorly understood. In particular, we do not know how fine root production develops following mangrove reforestation, despite fine root production being a major carbon sink and an important control of mangrove soil accretion.Using minirhizotrons, we investigated fine root production and its depth variation along a chronosequence of mature Vietnamese mangroves.Our results showed that fine root production decreases strongly with stand age in the uppermost 32 cm of our soil profiles. In younger mangrove stands, fine root production declines with depth, possibly due to a vertical gradient in soil nutrient availability; while root production in the oldest stand is low at all depths and exhibits no clear vertical pattern. A major fraction of fine root production occurs deeper than 30 cm, depths that are commonly omitted from calculations of mangrove carbon budgets.Younger mangroves may accrue shallow soil organic matter faster than older mangroves. Therefore, root productivity and forest stand age should be accounted for when forecasting mangrove carbon budgets and resistance to sea‐level rise. See also the Commentary on this article by Cormier, 232: 1525–1527. [ABSTRACT FROM AUTHOR]

Purpose: The effects of trees on soil nematode communities are related to nutrient cycles in forest ecosystems. We conducted greenhouse pot experiments to determine the effects of a single tree species for each of coniferous and broad-leaved tree on soil nematodes.Soils were collected from a coniferous plantation and broad-leaved forests. Seedlings of a coniferous tree (Cryptomeria japonica) and a broad-leaved tree (Quercus serrata) were planted in soils derived from each species. After 11 months, seedling biomass, soil properties, and ectomycorrhizal fungal colonization of Q. serrata were measured. Soil nematodes were morphologically identified to the genus/family level and differentiated by community and trophic composition.C. japonica root biomass was significantly higher than that of Q. serrata regardless of the soil and nematode community structures were significantly different between the species. The fungal: bacterial ratio and density of fungivorous nematodes were significantly higher in broad-leaved soils. Herbivorous nematodes increased significantly in C. japonica seedlings grown in broad-leaved soils. Structural equation modeling indicated that soil origin and tree species directly regulated nematode trophic compositions.Our findings suggest that tree species modify soil micro-food webs by affecting microbial abundance and nematode trophic composition. Specifically, C. japonica, with a larger root biomass, increased the number of herbivorous nematodes, whereas Q. serrata, with ectomycorrhizal fungal symbiosis, increased the number of fungivorous nematodes. Thus, tree species are tightly involved in shaping nematode communities in forest ecosystems through root traits and mycorrhizal types.Methods: The effects of trees on soil nematode communities are related to nutrient cycles in forest ecosystems. We conducted greenhouse pot experiments to determine the effects of a single tree species for each of coniferous and broad-leaved tree on soil nematodes.Soils were collected from a coniferous plantation and broad-leaved forests. Seedlings of a coniferous tree (Cryptomeria japonica) and a broad-leaved tree (Quercus serrata) were planted in soils derived from each species. After 11 months, seedling biomass, soil properties, and ectomycorrhizal fungal colonization of Q. serrata were measured. Soil nematodes were morphologically identified to the genus/family level and differentiated by community and trophic composition.C. japonica root biomass was significantly higher than that of Q. serrata regardless of the soil and nematode community structures were significantly different between the species. The fungal: bacterial ratio and density of fungivorous nematodes were significantly higher in broad-leaved soils. Herbivorous nematodes increased significantly in C. japonica seedlings grown in broad-leaved soils. Structural equation modeling indicated that soil origin and tree species directly regulated nematode trophic compositions.Our findings suggest that tree species modify soil micro-food webs by affecting microbial abundance and nematode trophic composition. Specifically, C. japonica, with a larger root biomass, increased the number of herbivorous nematodes, whereas Q. serrata, with ectomycorrhizal fungal symbiosis, increased the number of fungivorous nematodes. Thus, tree species are tightly involved in shaping nematode communities in forest ecosystems through root traits and mycorrhizal types.Results: The effects of trees on soil nematode communities are related to nutrient cycles in forest ecosystems. We conducted greenhouse pot experiments to determine the effects of a single tree species for each of coniferous and broad-leaved tree on soil nematodes.Soils were collected from a coniferous plantation and broad-leaved forests. Seedlings of a coniferous tree (Cryptomeria japonica) and a broad-leaved tree (Quercus serrata) were planted in soils derived from each species. After 11 months, seedling biomass, soil properties, and ectomycorrhizal fungal colonization of Q. serrata were measured. Soil nematodes were morphologically identified to the genus/family level and differentiated by community and trophic composition.C. japonica root biomass was significantly higher than that of Q. serrata regardless of the soil and nematode community structures were significantly different between the species. The fungal: bacterial ratio and density of fungivorous nematodes were significantly higher in broad-leaved soils. Herbivorous nematodes increased significantly in C. japonica seedlings grown in broad-leaved soils. Structural equation modeling indicated that soil origin and tree species directly regulated nematode trophic compositions.Our findings suggest that tree species modify soil micro-food webs by affecting microbial abundance and nematode trophic composition. Specifically, C. japonica, with a larger root biomass, increased the number of herbivorous nematodes, whereas Q. serrata, with ectomycorrhizal fungal symbiosis, increased the number of fungivorous nematodes. Thus, tree species are tightly involved in shaping nematode communities in forest ecosystems through root traits and mycorrhizal types.Conclusion: The effects of trees on soil nematode communities are related to nutrient cycles in forest ecosystems. We conducted greenhouse pot experiments to determine the effects of a single tree species for each of coniferous and broad-leaved tree on soil nematodes.Soils were collected from a coniferous plantation and broad-leaved forests. Seedlings of a coniferous tree (Cryptomeria japonica) and a broad-leaved tree (Quercus serrata) were planted in soils derived from each species. After 11 months, seedling biomass, soil properties, and ectomycorrhizal fungal colonization of Q. serrata were measured. Soil nematodes were morphologically identified to the genus/family level and differentiated by community and trophic composition.C. japonica root biomass was significantly higher than that of Q. serrata regardless of the soil and nematode community structures were significantly different between the species. The fungal: bacterial ratio and density of fungivorous nematodes were significantly higher in broad-leaved soils. Herbivorous nematodes increased significantly in C. japonica seedlings grown in broad-leaved soils. Structural equation modeling indicated that soil origin and tree species directly regulated nematode trophic compositions.Our findings suggest that tree species modify soil micro-food webs by affecting microbial abundance and nematode trophic composition. Specifically, C. japonica, with a larger root biomass, increased the number of herbivorous nematodes, whereas Q. serrata, with ectomycorrhizal fungal symbiosis, increased the number of fungivorous nematodes. Thus, tree species are tightly involved in shaping nematode communities in forest ecosystems through root traits and mycorrhizal types. [ABSTRACT FROM AUTHOR]

Background and aims: Identifying root types helps understand the diversity of the morphogenetic capacities of root axes. Unfortunately, root types are generally defined arbitrarily. We used an unsupervised clustering method to define root types and examine the ontogeny of the Pinus pinaster root system. Methods: K-clustering was first used on four root traits, including three geometric architectural traits: basal cross-sectional area, root tropism, parent root tropism, and branching angle. Based on these groups, we assigned all the root axes to a root type. Results: Clustering yielded the same five groups of lateral roots and explained the same percentage of variance (70%) whatever the tree age. This way, 11,004 root axes from 69 excavated root systems ranging from 3 to 50 years were assigned in 5 types. P. pinaster root axes showed large differences based on root tropism and parent root tropism intensity. The larger horizontal shallow roots represented most of the woody volume throughout the life cycle of the trees. The frame of the central part of the root system was almost completed in 4-year-old trees. Conclusions: In addition to the taproot, five types of lateral roots were identified in P. pinaster based on root geometry and size, and no consistent age effect was reported. This method could improve the connexion between root trait data and root modelling. [ABSTRACT FROM AUTHOR]

The root system architecture (RSA) of crops can affect their production, particularly in abiotic stress conditions, such as with drought, waterlogging, and salinity. Salinity is a growing problem worldwide that negatively impacts on crop productivity, and it is believed that yields could be improved if RSAs that enabled plants to avoid saline conditions were identified. Here, we have demonstrated, through the cloning and characterization of qSOR1 (quantitative trait locus for SOIL SURFACE ROOTING 1), that a shallower root growth angle (RGA) could enhance rice yields in saline paddies. qSOR1 is negatively regulated by auxin, predominantly expressed in root columella cells, and involved in the gravitropic responses of roots. qSOR1 was found to be a homolog of DRO1 (DEEPER ROOTING 1), which is known to control RGA. CRISPR-Cas9 assays revealed that other DRO1 homologs were also involved in RGA. Introgression lines with combinations of gain-of-function and loss-of-function alleles in qSOR1 and DRO1 demonstrated four different RSAs (ultra-shallow, shallow, intermediate, and deep rooting), suggesting that natural alleles of the DRO1 homologs could be utilized to control RSA variations in rice. In saline paddies, near-isogenic lines carrying the qSOR1 loss-of-function allele had soil-surface roots (SOR) that enabled rice to avoid the reducing stresses of saline soils, resulting in increased yields compared to the parental cultivars without SOR. Our findings suggest that DRO1 homologs are valuable targets for RSA breeding and could lead to improved rice production in environments characterized by abiotic stress. [ABSTRACT FROM AUTHOR]

Root growth and development has become an important research topic for breeders and researchers based on a growing need to adapt plants to changing and more demanding environmental conditions worldwide. Over the last few years, genome-wide association studies (GWASs) became an important tool to identify the link between traits in the field and their genetic background. Here we give an overview of the current literature concerning GWASs performed on root system architecture (RSA) in plants. We summarize which root traits and approaches have been used for GWAS, mentioning their respective success rate towards a successful gene discovery. Furthermore, we zoom in on the current technical hurdles in root phenotyping and GWAS, and discuss future possibilities in this field of research. [ABSTRACT FROM AUTHOR]

Background and aims: Trait-based approaches are increasingly used to improve ecological restoration in degraded ecosystems. The aim of this study was to evaluate how vegetation controls soil detachment capacity (Dc) by concentrated flow based on the linkages between root traits and soil physics. Methods: We selected 60 plots along a land degradation gradient caused by long-term water erosion in a small catchment, central China. These plots consisted of woodlands, scrublands, grasslands and bare lands. And soil physical properties, root traits and Dc were measured in each plot. Results: Fine roots (0.2 mm < diameter < 2 mm) accounted for 51–93% of total root length in topsoil. Roots explained most of the soil variations in noncapillary porosity, aggregate stability and shear strength. Furthermore, our prediction model (R2 = 0.88, NSE = 0.85) showed that fine roots length density and soil shear strength were the primary factors reducing Dc. Conclusions: Vegetation restoration improves multiple soil physical properties key to mitigating Dc, and the root functional traits play a substantial role in this relationship. These findings could provide the basis for soil conservation, and for expanding the pool of species of interest, which can be used to provide erosion mitigation services in degraded ecosystems. [ABSTRACT FROM AUTHOR]

• Increased GWD had regulated stomatal close to aggregate ability of WUE. • Plants reduced the RLD and adjusted the vertical distribution of root with increased GWD. • The key traits for responding productivity appear to be GWD, SM, leaf traits, and root traits. Climate change and human development will lead to an increase in groundwater levels. This will have a particularly severe impact on arid ecosystems that are highly dependent on groundwater, as overconsumption and pollution of water resources can lead to faster depletion of groundwater. This not only exacerbates the problem of groundwater scarcity, but also may have profound impacts on local ecological environment and biodiversity. However, previous research has focused on aboveground trait responses to precipitation deficits, with less emphasis on concomitant belowground impacts and deep soil drought from groundwater depletion. Therefore, it remains unclear how groundwater depletion affects above and belowground traits of plant to jointly regulate aboveground biomass. In this study, we assessed morphological and ecophysiological traits of two dominant species (herb: Pennisetum centrasiaticum and shrub: Artemisia halodendron) across three groundwater depth (50 cm, 100 cm, and 200 cm) in the Horqin Sandy Land in China, within which photosynthetic rate (Photo), stomatal conductance (Cond), transpiration rate (Tr), internal CO 2 concentration (Ci), instantaneous water-use efficiency of leaves (Lwue), total nitrogen (LN) and phosphorus (LP) content of the leaves, root to shoot ratio (RSR), root length density (RLD), total root length (RTL), root length ratio (RLR) were measured. The result showed that the two species growing with increased groundwater depth had reduced photosynthetic rate, and regulated stomatal close to aggregate ability of instantaneous water use efficiency, which may allow plants to meet resource demands under drought stress avoiding transpiration water loss. Plants also reduced the density of all roots and adjusted the vertical distribution of coarse root by changing biomass distribution to acquire deeper soil available water. Correlation analysis showed that the vital traits for aboveground biomass responses appear to be groundwater depth, soil moisture, leaf area, photosynthesis, water use efficiency, and root traits. Overall, the biomass production response of two dominant species may be greatly influenced by the interaction between aboveground and belowground traits in response to changes in groundwater depth. This result contributes to our understanding of adaptive strategies of vegetation in sandy soils and provides additional support for enhancing vegetation productivity in semi-arid ecosystems. The ability of semi-arid ecosystems to predict vegetation dynamics under current and future increasing groundwater depths is crucial. [ABSTRACT FROM AUTHOR]

1. Considering intraspecific trait variability (ITV) in ecological studies has improved our understanding of species persistence and coexistence. These advances are based on the growing number of leaf ITV studies over local gradients, but logistical constraints have prevented a solid examination of ITV in root traits or at scales reflecting species’ geographic ranges. 2. We compared the magnitude of ITV in above‐ and below‐ground plant organs across three spatial scales (biophysical region, locality and plot). We focused on six understorey species (four herbs and two shrubs) that occur both in disturbed and undisturbed habitats across boreal and temperate Canadian forests. We aimed to document ITV structure over broad ecological and geographical scales by asking: (a) What is the breadth of ITV across species range‐scale? (b) What proportion of ITV is captured at different spatial scales, particularly when local scale disturbances are considered? and (c) Is the variance structure consistent between analogous leaf and root traits, and between morphological and chemical traits? 3. Following standardized methods, we sampled 818 populations across 79 forest plots simultaneously, including disturbed and undisturbed stands, spanning four biophysical regions (~5,200 km). Traits measured included specific leaf area (SLA), specific root length (SRL) and leaf and root nutrient concentrations (N, P, K, Mg, Ca). We used variance decomposition techniques to characterize ITV structure across scales. 4. Our results show that an important proportion of ITV occurred at the local scale when sampling included contrasting environmental conditions resulting from local disturbance. A certain proportion of the variability in both leaf and root traits remained unaccounted for by the three sampling scales included in the design (36% on average), with the largest amount for SRL (54%). Substantial differences in magnitude of ITV were found among the six species, and between analogous traits, suggesting that trait distribution was influenced by species strategy and reflects the extent of understorey environment heterogeneity. 5. Even for species with broad geographical distributions, a large proportion of within‐species trait variability can be captured by sampling locally across ecological gradients. This has practical implications for sampling design and trait selection for both local studies and continental‐scale modelling. [ABSTRACT FROM AUTHOR]

Chickpea parents with contrasting root characters and their direct and reciprocal crosses were evaluated under control and drought stress created by withholding irrigation using specially designed root boxes at 50 per cent flowering stage. The crosses involving Vijay and ICC 4958 having deep and prolific root system as a male parent exhibited higher accumulation of osmolytes (proline and glycine betaine) and with higher activities of antioxidative enzymes (SOD, APX, CAT and GPX) with less increase in lipid peroxidation rate and less decrease in nitrate reductase. Amongst the chickpea crosses, the cross of ICC 4958 x Vijay recorded higher increase in root length of 78.77 percent with less reduction in RLWC. The high estimates of broad sense heritability and genetic advance as percent mean was observed in F2 generations of direct and reciprocal crosses for long root length. [ABSTRACT FROM AUTHOR]

Background and aims: Each genotype within species has a particular combination of root morphological and/or physiological traits to adapt to phosphorus-limited environments, which can lead to its unique plant fitness and competitive ability. Yet, how the various phosphorus environments affect the competition between genotypes remains obscure.Methods: Two maize (Zea mays L.) genotypes (XY335 and HMY, bred in nutrient-rich and nutrient-poor environments, respectively) were grown in monoculture and mixture in phosphorus-limited soil with homogeneous or heterogeneous supply patterns and inorganic (Pinorg) or organic phosphorus (Porg) forms.Results: In homogeneous Pinorg and Porg environments, XY335 had higher root length and surface area, but lower mycorrhizal colonization and the acid phosphatase and phytase activities in the rhizosphere, than HMY. In heterogeneous phosphorus environments, XY335 had higher root proliferation than HMY. The root trait divergence influenced the competition in mixture: XY335 had a competitive advantage compared to HMY under heterogeneous phosphorus conditions, whereas HMY exhibited a stronger competitive ability in homogeneous phosphorus treatments; these reverse trends were more significant in the Porg than Pinorg treatments.Conclusions: The results suggested the importance of root physiological traits in homogeneous phosphorus-limited soil environments, whereas P acquisition strategy based on root morphological traits favours heterogeneous phosphorus supply. [ABSTRACT FROM AUTHOR]

Triticum boeoticum wild wheat is a remarkable gene pool to environmental stress resistance. It is one of the most valuable species of the Triticeae tribe for improving wheat cultivars to moisture-stress. This research was carried out to assess the changes and responses of different traits of 10 accessions of Triticum boeoticum under non-stress and imposed moisture stress conditions in 2015 and 2016. Most traits were significantly affected by accession (A), water treatments (WT), and A×WT interactions. The accessions showed a high-level of genetic diversity for all traits, except peduncle weight. The accessions Tb5 and TB3 with the highest amount of economic yield per plant (EYPP) and water use efficiency (WUE), were less affected by the imposed moisture stress, while accession Tb6 with the maximum amount of water use (WU), main root length (MRL) and some phenological traits, were the most affected. The traits of WUE and main stem weight (MSTW) showed the highest and the traits of excised leaf water retention (ELWR), MRL and WU showed the lowest alignment with EYPP, respectively. The ability of producing assimilates (by increasing biological yield per plant and MSTW) and the ability of faster assimilates-remobilization into grains (by increasing harvest index and WUE), has been a neglected aspect of breeding wheat program under drought stress. In other words, the ability of a genotype to produce more assimilates and allocate it to grains (by increased BYPP and WUE, respectively) instead of belowground-traits, will result to increase EYPP. For example, the Tb6 ecotype, due to the allocation of more assimilates to underground parts, had little grain yield. While the traits of WUE, BYPP, seed number per main spike, seed weight per main spike (SWPMS) and main spike weight (MSPW) showed a positive and significant (P<0.01) correlation to EYPP, the traits of ELWR, MRL, day to heading and day to anthesis, had a negative and significant (P<0.05) correlation with yield. Generally, a high amount of WUE, MSTW, SWPMS, MSPW and peduncle weight; with a low amount of ELWR, phenological traits (except grain filling period), MRL, WU, and root to shoot dry weight ratio (RDWSDW) were suggested for the improvement of grain yield. SWPMS and MSPW were two main-components of grain yield in the favorite accessions (Tb5 and Tb3). Tb5 and Tb3 may have value for breeding wheat better adapted to moisture stress conditions in future. [ABSTRACT FROM AUTHOR]

Root system is an important factor for crop productivity under water- and nutrient-limited environments. A pot study was conducted to evaluate root system response of three Thai rice varieties (Pathumthani 1, RD57, RD41) under three cultivation methods (dry direct seeding [DDS], wet direct seeding [WDS], transplanting [TP]) and three levels of alternate wetting and drying irrigation (-5, -15, -30 kPa). A second pot experiment examined the effect of potassium (K) rates (0, 80, 120, 160 kg ha-1) on root system response of the same varieties under DDS and TP subjected to alternate wetting and drying at -5 kPa. Pathumthani 1 was more tolerant to moisture stress; RD57 and RD41 showed an inconsistent response to moisture-deficit conditions. Rice plant under TP was more sensitive to moisture stress; rice plant performed better under DDS even at the highest soil moisture stress of -30 kPa. K application at the rate of 120 kg ha-1 as basal under DDS was optimum for root system development of Pathumthani 1, while RD57 and RD41 had higher actual root length at the same K rate regardless of cultivation methods. Alternate wetting and drying up to -30 kPa could be safely applied for the three tested varieties. The performance of root system of Pathumthani 1 was better under DDS method of cultivation. K fertilization at 120 kg ha-1 can be recommended as optimum rate under water-saving cultivation techniques for the three tested varieties. [ABSTRACT FROM AUTHOR]

Understanding the shoot-root characteristics and their interaction of maize is essential to break the constraints of the densification process and improve grain yield. The objective of the work was to study the interaction between the above-ground canopy and below-ground root system in morphology and its relationship to grain yield in dense planting with different hybrids. This study conducted a 2-yr field experiment with three modern hybrids (JNK728, ZD958 and XY335) at the Wuqiao Experimental Station in Northern China. Among hybrids, XY335 attained the highest grain yield of 14,886.9 kg hm−2 in 2019 and 10,078.8 kg hm−2 in 2020 with a density of 7.5 × 104 plants hm−2. For the shoot at the silking stage (R1), the lowest leaf orientation value for both middle and upper leaves and ear-to-height ratio among three hybrids were found in XY335 with the compact plant phenotype. Meanwhile, the highest photosynthesis rate of ear leaves (33.0 umol m2˙s−1) at R1 was also observed in XY335. At physiological maturity (R6), the above-ground dry matter (AGDM) was 4.6%− 10.4% higher in XY335 than the other two hybrids. For the root system at both R1 and R6 with the density of 7.5 × 104 plants hm−2, the highest value for root system indicators in morphology such as root total length (RL), root surface area (RSA), root volume (RV) was observed in XY335. From R1 to R6, RL, RSA and RV in XY335 averaged 24,749.6 cm, 3486.8 cm2, 51.5 cm3, 1.3–14.6% higher than JNK728, and 10.2–23.9% higher than ZD958, respectively. Furthermore, the lower senescence of the root system was also observed in XY335, with a 22.0–32.1% lower decrease from R1 to R6 in RL, RSA, and RV compared with the other two hybrids. For the shoot-root interaction, per unit decrease in morphology indicator in the root per plant with density increase of XY335 accompanied with more AGDM accumulation and thus higher grain yield. The observations on shoot-root characteristics and their interaction from this study are essential to selecting a hybrid that allows a better adaptation to planting at high density, developing an effective management strategy, and breeding high-density tolerant hybrids. • We studied the shoot-root interaction under dense planting with different hybrids. • 2-yr field experiment with hybrids of JNK728, ZD958 and XY335 were conducted. • XY335 had the highest grain yield and higher above-ground dry matter (AGDM). • XY335 had a compact plant phenotype with a larger, lower senescence root system. • XY335 had more AGDM with less root decrease under dense planting. [ABSTRACT FROM AUTHOR]

* Background and Aims In several disciplines, identifying relevant root traits to characterize the root system architecture of species or genotypes is a crucial step. To address this question, we analysed the inter-specific variations of root architectural traits in two contrasting environments. * Methods We sampled 60 species in natura, at two sites, each presenting homogeneous soil conditions. We estimated for each species and site a set of five traits used for the modelling of the root system architecture: extreme tip diameters (Dmin and Dmax), relative diameter range (Drange), mean inter-branch distance (IBD) and dominance slope between the diameters of parent and lateral roots (DlDm). * Key Results The five traits presented a highly significant species effect, explaining between 77 and 98 % of the total variation. Dmin, Dmax and Drange were particularly determined by the species, while DlDm and IBD exhibited a higher percentage of environmental variations. These traits make it possible to confirm two main axes of variation: 'fineness-density' (defined by Dmin and IBD) and 'dominance-heterorhizy' (DlDm and Drange), that together accounted for 84 % of the variations observed. * Conclusions We confirmed the interest of these traits in the characterization of the root system architecture in ecology and genetics, and suggest using them to enrich the 'root economic spectrum'. [ABSTRACT FROM AUTHOR]

As a primitive hexaploid wheat resource distributed only in Tibet, Tibetan semi-wild wheat ( Triticum aestivum subsp. tibetanum Shao) possesses unique characteristics that could be exploited in wheat breeding programs. Its good root system could offer a stable platform for above-ground components. To detect possible excellent locus for root traits from Tibetan semi-wild wheat, we identified QTLs for root traits using a recombinant inbred line population derived from a cross between Tibetan semi-wild wheat Q1028 and Zhengmai 9023. A total of 15 QTLs on eight chromosomes were detected, including four major QTLs, QMrl.sau-7B, QTrl.sau-4B, QAd.sau-7A, and QSa.sau-4B. The phenotypic variation explained by each of these QTLs ranges from 5.67% to 16.68%. Positive alleles of six QTLs were derived from Q1028. Several novel QTLs for root traits were identified. In addition, significant correlations were detected amongst root traits and agronomic traits. Taken together, these results suggest that Tibetan semi-wild wheat and the newly identified novel QTLs could be useful in future breeding programs. [ABSTRACT FROM AUTHOR]

The analysis of residuals computes general adaptabilities (GAs) and specific adaptabilities (SAs) of genotypes similar to combining ability analysis. The residual analysis is simple and robust being based on the first-degree statistics, and is assumption-free. A unique statistic of ratio of variances (VR) of residuals for individual genotypes allows comparing their stability. The residuals analysis of genotype × environment (GE) interactions was performed for grain yield (t ha−1) of 25 rice (Oryza sativa L.) genotypes, including two developed by marker-assisted selection for root traits quantitative trait loci (QTL), tested across 16 sites. Results were compared with the linear regression analysis for (i) full set of 16 sites showing adequacy of linear model and (ii) subset of nine-poor sites showing inadequacy of linear model. There was agreement between the two analyses for situation (i) but not for situation (ii) when the regression analysis fails because of nonlinearity but the residual analysis retains its validity. [ABSTRACT FROM PUBLISHER]

In grasslands, grazing can regulate the functional trait composition of plant communities through intraspecific trait variation and species turnover. However, it is not well understood how these variables affect specific plant traits. Here, we partitioned the relative roles of intraspecific trait variation and species turnover to control grazing-induced shifts in community functional composition using a field manipulation experiment with seven levels of grazing intensity in the Inner Mongolia grassland. We concurrently measured six aboveground traits (i.e. plant height, plant aboveground biomass, plant density, leaf area, specific leaf area, SLA; and leaf density) and three root traits (average root diameter, ARD; specific root length, SRL; and root tissue density, RTD) of the first-, second- and third-order roots (1st-, 2nd-, and 3rd-). Our results showed that plant above-ground traits shifted towards grazing avoidance strategies (i.e. plant height and leaf area decreased) as grazing intensity increased, and below-ground traits shifted towards conservation strategies (i.e. 1st-SRL and 2nd-SRL decreased, 1st-RTD and 2nd-ARD increased). Additionally, functional tradeoffs were found between plant individual biomass and plant density, as well as between leaf area and leaf density under grazing. However, community-weighted mean SRL (SRL CWM) and ARD (ARD CWM) exhibited functional coordination under the grazing pressures. Altogether, shifts in community functional trait composition were predominantly governed by intraspecific variation in above- and below-ground traits, while changes in mean trait values among plant species with different resource strategies were mainly triggered by species turnover. Our results demonstrated that both above- and below-ground trait compositions in plant communities shifted towards conservation strategies under high levels of grazing intensity. Ultimately, this study highlights the important role of intraspecific trait variation in governing grazing-induced changes in the community above- and below-ground functional trait composition, which advances fundamental knowledge on the mechanisms of plant community assembly in semiarid grasslands. • Grazing regulates plant functional traits and community trait composition in grasslands. • Grazing shifted trait composition of plant communities towards conservation strategies. • Intraspecific trait variation governs variations in community trait composition. • Plant community above- and below-ground trait composition are synergistic under grazing. [ABSTRACT FROM AUTHOR]

While ecological roles of rhizosphere arthropods are well documented, little is known about the relationship between the development of plant roots and soil arthropod communities in agroecosystems. In this study, we investigated the effects of maize varieties and their root traits on the diversity and community composition of soil arthropods over time. Soil arthropods and root traits were evaluated before planting and at 30 and 60 days after planting in four maize varieties with different root growth angles and lateral root branching. Arthropod diversity declined from day 0 to 30 but recovered by day 60 with the development of maize roots. Two maize varieties (Nei 542018 and Nei 542022) exhibited lower brace and crown root angles, and arthropod taxon richness was greater in these two varieties than in others. The highest abundance of detritivores and predators was found in one of the maize varieties (Nei 542018) which, in addition to lower root angle, attained greater root diameter and lateral root branching and length. Redundancy analysis indicated that soil arthropod composition was correlated with crown root angle. Our findings highlight the importance of root traits, especially the angle of the roots, to enhance arthropod biodiversity in the rhizosphere ecosystem. [Display omitted] • Soil without maize root have lower diversity of arthropod than rhizosphere soil. • Maize root traits, specifically crown root angle, influence arthropod diversity and functional guild abundance in rhizosphere. • Rhizosphere of shallow root have higher abundance and taxon richness of arthropods due to greater available of resource. [ABSTRACT FROM AUTHOR]

Fine root is of importance in biogeochemical cycles especially in terrestrial ecosystems. The lack of understanding of the factors controlling root lifespan has made accurate prediction of carbon flow and nutrient cycling difficult. A controlled warming experiment was performed in an alpine meadow on the northern Tibetan Plateau (near Nagchu Town). We used a minirhizotron technique to measure root dynamics in situ during the growing season of 2013 and 2014 and survival analyses to assess root lifespan and the effects of root diameter, branch order, birth season, root depth and warming on root lifespan. Root diameter, branch order and root depth were all positively correlated with root lifespan. With an increase in diameter of 0.1 mm, mortality hazard ratio of roots declined by 19.3 %. An increase in one level in branch order was associated with a decrease of 43.8 % in root death ratio. Compared with roots born in May-mid-July, the mortality hazard ratio of roots born in late July-August and September-October reduced by 26.8 and 56.5 %, respectively. In warming treatments, roots tended to be thinner, less branched and deeper, and there was a higher proportion of roots born in spring compared to ambient conditions. Warming shortened the median root lifespan 44 days. However, in single warming condition, root diameter had no significant influence on root lifespan. Root diameter, branch order, root depth and season of birth were all factors affecting root lifespan in the alpine meadow; however, root branch order was dominant. [ABSTRACT FROM AUTHOR]

Narrow-leafed lupin (Lupinus angustifolius L.) is the predominant grain legume crop in southern Australia, contributing half of the total grain legume production of Australia. Its yield in Australia is hampered by a range of subsoil constraints. The adaptation of lupin genotypes to subsoil constraints may be improved by selecting for optimal root traits from new and exotic germplasm sources. We assessed root trait diversity and genetic diversity of a core collection of narrow-leafed lupin (111 accessions) using 191 Diversity Arrays Technology (DArT) markers. The genetic relationship among accessions was determined using the admixture model in STRUCTURE. Thirty-eight root-associated traits were characterized, with 21 having coefficient of variation values >0.5. Principal coordinate analysis and cluster analysis of the DArT markers revealed broad diversity among the accessions. An ad hoc statistics calculation resulted in 10 distinct populations with significant differences among and within them (P < 0.001). The mixed linear model test in TASSEL showed a significant association between all root traits and some DArT markers, with the numbers of markers associated with an individual trait ranging from 2 to 13. The percentage of phenotypic variation explained by any one marker ranged from 6.4 to 21.8%, with 15 associations explaining >10% of phenotypic variation. The genetic variation values ranged from 0 to 7994, with 23 associations having values >240. Root traits such as deeper roots and lateral root proliferation at depth would be useful for this species for improved adaptation to drier soil conditions. This study offers opportunities for discovering useful root traits that can be used to increase the yield of Australian cultivars across variable environmental conditions. [ABSTRACT FROM AUTHOR]

Background and aims: Our objectives were to evaluate changes in soil aggregate stability along a successional gradient, located in severely eroded Mediterranean gully bed ecosystems and to identify predictors of soil aggregate stability variations among several soil, root traits and plant community characteristics. Methods: We selected 75 plots in gully beds, representing five successional stages that differ in plant community composition, dominated by herbs, shrubs or trees according to successional stage. In each plot, we measured soil aggregate stability, basic soil characteristics, root traits and plant diversity indices. Results: Soil aggregate stability increased along the successional gradient, being thrice higher in tree-dominated communities as compared to grass-dominated communities. This increase was mainly driven by soil organic carbon (SOC) accumulation. In early successional stages showing low SOC (below 24 g.kg or 12 g.kg in some cases), fine sand content and the percentage of fine roots acted as co-drivers enhancing soil aggregate stability while silt content decreased it. Conclusion: Plant succession in severely eroded Mediterranean gully bed ecosystems is accompanied by a strong stabilization of soil aggregates, mainly driven by SOC accumulation and for early successional stages, by soil granulometry and root traits as co-drivers. Stimulating succession thus appears as a promising restoration strategy for severely eroded ecosystems. [ABSTRACT FROM AUTHOR]

Background and aims: In order to analyse root system architectures (RSAs) from captured images, a variety of manual (e.g. Data Analysis of Root Tracings, DART), semi-automated and fully automated software packages have been developed. These tools offer complementary approaches to study RSAs and the use of the Root System Markup Language (RSML) to store RSA data makes the comparison of measurements obtained with different (semi-) automated root imaging platforms easier. The throughput of the data analysis process using exported RSA data, however, should benefit greatly from batch analysis in a generic data analysis environment (R software). Methods: We developed an R package (archiDART) with five functions. It computes global RSA traits, root growth rates, root growth directions and trajectories, and lateral root distribution from DART-generated and/or RSML files. It also has specific plotting functions designed to visualise the dynamics of root system growth. Results: The results demonstrated the ability of the package's functions to compute relevant traits for three contrasted RSAs ( Brachypodium distachyon [L.] P. Beauv., Hevea brasiliensis Müll. Arg. and Solanum lycopersicum L.). Conclusions: This work extends the DART software package and other image analysis tools supporting the RSML format, enabling users to easily calculate a number of RSA traits in a generic data analysis environment. [ABSTRACT FROM AUTHOR]

Our objective was to calibrate a model of the root system architecture on several Poaceae species and to assess its value to simulate several 'integrated' traits measured at the root system level: specific root length ( SRL), maximum root depth and root mass., We used the model Archi Simple, made up of sub-models that represent and combine the basic developmental processes, and an experiment on 13 perennial grassland Poaceae species grown in 1.5-m-deep containers and sampled at two different dates after planting (80 and 120 d)., Model parameters were estimated almost independently using small samples of the root systems taken at both dates. The relationships obtained for calibration validated the sub-models, and showed species effects on the parameter values. The simulations of integrated traits were relatively correct for SRL and were good for root depth and root mass at the two dates. We obtained some systematic discrepancies that were related to the slight decline of root growth in the last period of the experiment., Because the model allowed correct predictions on a large set of Poaceae species without global fitting, we consider that it is a suitable tool for linking root traits at different organisation levels. [ABSTRACT FROM AUTHOR]

Question: The quantification of functional traits in natural communities can be difficult (e.g. root traits, RGR). Can functional traits measured on pot grown plants be reliably applied to natural communities? Alternatively, can below-ground plant traits be predicted from above-ground traits? Location: Southeastern Australia. Methods: We compared 17 shoot, root and whole-plant morphological traits measured on 14 plant species in a native grassland community to those measured under two different pot conditions: unfertilised and fertilised. Results: The majority of trait values for pot grown plants differed to plants in the field, however, species ranking remained consistent for most leaf traits between the field and the two pot growing conditions. In contrast, species ranking was not consistent for most whole plant traits when comparing field plants to fertilised pot grown plants, providing a caution against the tendency to grow plants in controlled conditions at 'optimal' (high) resource levels. Moderate to strong correlations were found between below-ground and above-ground plant traits, including between root dry matter content and leaf dry matter content, and between specific root area and specific leaf area. Conclusions: The utility of pot grown plants to quantify traits for field plants is highly dependent on the selection of the growing conditions in the controlled environment. The consistency we observed between above-ground and below-ground trait strategies suggests that below-ground traits may be predictable based on above-ground traits, reducing the need to quantify root traits on cultured plants. [ABSTRACT FROM AUTHOR]

• Conservation agriculture (CA) and conventional tillage (CV) were compared • Root parameters in maize-soybean-winter wheat rotation cycle were studied • CA increased root length density at 0–10 cm owing to increased nutrients • The yield gap between CA and CV may have been due to weed control Conservation agriculture (CA) is a farming system that promotes minimum soil disturbance, maintenance of a permanent soil cover, and diversification of plant species and was introduced also in the Veneto region of north east Italy. CA is not always viewed as a win-win solution for sustainable production because of the increase in soil strength and compaction that may negatively impact root growth and crop production. In this study, our aim was to analyse root length density (RLD), mean diameter (MD), and root distribution to 90 cm at the flowering stage, following a maize-soybean-winter wheat rotation cycle under CA and conventional tillage (CV) at four farms. Root traits were related to soil physical properties (gravimetric water content, bulk density, and electrical resistivity) and to existent critical limits of penetration resistance (PR), and the degree of compactness (DC). CA management was not detrimental to root development and positively affected the RLD of maize (+70 %), soybean (+121 %) and winter wheat (+20 %) at 0–10 cm most likely because of increased nutrient availability. No specific physical limitations of soil were highlighted for the crop root apparatus in three (silty soils) out of four farms. Farm 3 (sandy soil) with a hardpan below 35 cm caused lateral root development in winter wheat, but not in maize or soybean. The yield gap between CA and CV (-3.9 t ha−1 for maize, -0.4 t ha-1 for soybean and -0.7 t ha-1 for winter wheat) may have been due to other agronomic factors, notably insufficient weed control in CA. Critical limits of PR (2 or 33.5 MPa) and DC (87 %) did not seemed to impair root traits, irrespective of the tillage system, suggesting that further studies on soil-specific mechanisms between soil compaction and root apparatus are warranted. [ABSTRACT FROM AUTHOR]

• A linear source infiltrability measurement system was applied to capture the complete infiltration processes. • Grasses promote soil physical properties and infiltrability better than shrubs in heavy-textured soil. • The effects of plant roots on soil infiltrability are mediated via soil aggregate stability and soil porosity. • Species mixtures require inclusion of high fine root length density grasses to mitigate overland flow and erosion. Soil degradation impairs ecosystem functions, and vegetation restoration is a major eco-engineering method that is used to restore soils globally. Despite the fundamental role that plants play in enhancing soil functions and ecosystem services, little is known about the relationships among root traits, soil physical properties, and water infiltration. The objectives of this study were to therefore evaluate changes in soil infiltrability due to different vegetation types and identify soil properties and root trait predictors of variation in soil infiltrability. The influences of four plant species (two gramineous grasses and two leguminous shrubs) on physical properties of soil and water infiltration in heavy-textured soils with 43 % clay content following five years of restoration after surface soil removal were investigated. These data were subsequently incorporated into a conceptual path model to quantify the direct and indirect effects of root traits and root-induced soil properties on infiltration. Soil organic matter, aggregate stability, soil total porosity, and non-capillary porosity were significantly higher in planted soil than in bare soil (p < 0.05), following the order of grass-planted > shrub-planted > bare soils. The infiltration rates during the initial and steady states were 63 % and 38 % higher in grass-planted soils than in shrub-planted soils, respectively. Among all evaluated root traits, fine root length density was the best predictor of these changes. Furthermore, the conceptual path model explained 82 % of the variance in water infiltration and confirmed the important role of roots in soil infiltration. Modeling indicated that this might not be a direct effect, but is rather mediated via soil physical properties like soil aggregate stability and soil porosity. These observations have important implications for designing efficient strategies in restoration of human-induced disturbed soils to mitigate overland flows and erosion. [ABSTRACT FROM AUTHOR]

Maize root system architecture determines key functions of uptake of water and nutrients in plants. A large number of quantitative trait loci (QTLs) of root-related traits have been found in different populations of maize. Identification of consistent QTLs across diverse genetic backgrounds could be instrumental on marker-assisted selection of traits and identification of candidate functional genes. In this study, 20 published papers were investigated regarding on reported results of QTLs related to root traits of maize, and in total 428 individual QTLs for 23 root-related traits were used for meta-analysis, resulting in 53 Meta-QTLs (MQTLs) retrieved over ten maize chromosomes. Among these MQTLs regions, in total 45 maize homologs were considered as candidate genes affecting maize root traits by comparing with 7 genes from rice and 36 genes from Arabidopsis. Three maize genes (GRMZM5G813206, GRMZM2G167220 and GRMZM2G467069) identified from MQTL8-5 could play important roles on lateral root and crown root development of maize. Two of the MQTLs, i.e. MQTL7-2 and MQTL9-1, involved in nitrogen (N) and phosphorus (P) stress responses and both of them with small physical distance (less than 3 Mb), could be used for abiotic stress improvement of maize root traits. These MQTLs and candidate genes will be helpful for future gene cloning and marker-assisted selection in maize. [ABSTRACT FROM AUTHOR]