Extensive Root System Research Articles

Utilization of water hyacinth in constructed wetlands for wastewater treatment

Municipal wastewater discharge is one of the most serious threats to the ecosystem. The sewage needs to be treated appropriately before the wastewater can be released into the environment. In recent years, the application of constructed wetlands, and facultative ponds treating domestic sewage has attracted attention because it is environmental approach. Vegetation considered as a dominant feature of constructed wetlands, and acts as a biotic factor in the treatment process. The water hyacinth (Eichhornia crassipies) appears to be a promising candidate for pollutants removal owning to its rapid growth rate and extensive root system. This study is conducted to determine the efficiency of water hyacinth in wastewater treatment for nutrient removal and to identify the best practices for water hyacinth cultivation in the sewage treatment plant (STP). Plant growths and water quality were measured to determine the suitability of water hyacinth for sewage treatment plant. Water hyacinth has a good potential to be utilized in constructed wetlands for wastewater treatment.

Smallholder farmers expand production area of the perennial crop enset as a climate coping strategy in a drought‐prone indigenous agrisystem

Societal Impact StatementClimate resilient crops will become increasingly important, especially in regions where smallholder farmers are vulnerable to climate extremes. Enset, a multipurpose perennial staple crop consumed by over 20 million people in Ethiopia, purportedly provides food security during periods of drought. Here, we find evidence that frequent severe drought events led to an increase in enset production area. This is consistent with a broader pattern whereby farmers preferentially cultivate perennial and storable crops after long‐term drought events, providing an example of adaptation to fluctuations in climate through crop choice in indigenous agrisystems.SummarySmallholder farms in the semiarid and subhumid tropics are particularly vulnerable to increased climate variability. Indigenous agrisystems that have co‐evolved with climate variability may have developed resilience strategies. In the Southwest Ethiopian Highlands, agrisystems are dominated by the multipurpose perennial staple enset (Ensete ventricosum), characterised by flexible harvest timing, high yield, long storage, and putative drought tolerance, earning it the name ‘the tree against hunger’.We tested three hypotheses using crop production area and climate data. First, that enset production area is greatest in the most drought‐prone locations. Second, that farmers respond to drought events by increasing enset production area. And third, that drought encourages shifts in agrisystem composition more widely towards perennial or storable crops.We found that regions with a higher severe drought frequency are associated with significantly higher proportion of enset production. Similarly, the Standardised Precipitation Evapotranspiration Index of the previous 3 years is significantly negatively correlated with enset production area time series, suggesting that prior drier conditions led farmers to increase the land under enset production. Regarding other crops, storage crops roots and tubers were also preferentially selected after long‐term drought over annual crops, indicating their capacity for longer‐term resilience.Promoting the production of crops such as perennials, which have more extensive and established root systems, may be a strategy to ensure food security during drought or climate variability. These results indicate the potential of farmer's resilience strategies to improve food security in a changing climate.

Microbial Consortium Inoculum with Rock Minerals Increased Wheat Grain Yield, Nitrogen-Use Efficiency, and Protein Yield Due to Larger Root Growth and Architecture

Polymer-coated rock mineral fertiliser (RMF) has the potential to increase wheat growth and yield; however, its effect on grain protein concentration (GPC) and nitrogen-use efficiency (NUE) remains unclear. Therefore, we examined the efficacy of slow-release RMF combined with microbial consortium inoculant (MI) compared with inorganic fertiliser (IF) with or without the MI to explore their effects on wheat growth, NUE, GPC, grain protein yield and grain yield. The glasshouse experiment was conducted with three factors (fertiliser type (control, RMF and IF), fertiliser rate (0, 23 and 46 mg N kg−1 soil), and MI (with or without)) replicated four times and harvested twice (anthesis and maturity). The treatments were arranged in a randomised complete block design. NUE was higher in plants treated with RMF plus MI compared to IF (with or without MI), likely due to extensive root system, higher shoot N content (at anthesis and maturity) and grain N content in plants treated with RMF plus MI than IF. The application of RMF enhanced grain yield and GPC compared with IF. The grain yield increased due to more grains in RMF-treated than IF-treated plants. The RMF application increased N content in shoots at anthesis and maturity and grain N content, which increased GPC compared to IF-treated plants. RMF in combination with MI can be viewed as a practical approach to assist RMF in supplying nutrients to improve NUE, grain yield and GPC in wheat.

The influence of soil types and fertilizers on growth parameters of three goatgrass species (Aegilops) from the coastal plains of Israel: A. sharonensis Eig, A. longissima Schwienf. et Muschl. and A. speltoides Tausch

Three species of goatgrass (Aegilops L.), the wild relative of wheat, grow naturally in the coastal plains of Israel. The distribution and ecological parameters of Aegilops sharonensis were determined by a field survey, while similar information on the other species was obtained from the BioGIS database. The distribution of plants was soil-specific. Sharon goatgrass (A. sharonensis Eig) is endemic to Israel and southern Lebanon's coastal plains, which have been stabilized with dunes and sandy soils. In contrast, slender goatgrass (A. longissima Schwienf. et Muschl.) grows mainly on sandy loam and the truncate goatgrass (A. speltoides Tausch) grows primarily on heavy alluvial soils. The present 4-month study evaluated the affinity between these 3 Aegilops species, the 3 different types of soils and fertilizer application, in buckets. Interestingly, a significant increase in the number and weight of the spikes were observed in fertilized buckets. We could also find that these 3 species preferred heavy alluvial soil over the sands, regardless of the fertilizer treatment. The data suggested that the population of A. sharonensis was limited to the sandy dunes by urbanization along the coastal plane and aggressive competition with the other species. Their more extended root system may adapt A. sharonensis to the deep and salty groundwater that characterizes dunes. It is suggested to keep representatives of the Israeli Aegilops populations in a nature reserve for protection from extinction.

Differential effects of elevated atmosphere CO2 concentration on root growth in association with regulation of auxin and cytokinins under different nitrate supply

An extensive root system is one of the highly desirable traits for plant growth and adaptation to environmental stresses which is affected by the availability of atmosphere CO 2 and nitrogen (N) nutrition. The objectives of this study were to examine the interactive effects of elevated CO 2 and nitrogen on root growth and underlying regulatory mechanisms related to hormones metabolism in tall fescue ( Festuca arundinacea ). Plants (cv. ‘Barlexas’) were hydroponically grown in nutrient solution with low N (0.25 mM) and moderate N (4 mM) conditions and exposed to ambient CO 2 concentration (400 µmol·mol −1 ) or elevated CO 2 concentration (800 µmol·mol −1 ) for 35 days. Elevated CO 2 differentially promoted root growth under different nitrate levels. The longest root length, root biomass and all types of roots including the length, number, volume and surface area of both crown and lateral roots were enhanced by elevated CO 2 under moderate nitrate but without significant effects on crown root number under low nitrate condition. The extent of elevated CO 2 -promotion on lateral root was greater under moderate nitrate than that under low nitrate condition. The improvement of elevated CO 2 on root growth under moderate nitrate condition was related with increased content of indoleacetic acid (IAA) and isopentenyl adenosine (iPA) through up-regulating genes in auxin synthesis, cytokinin synthesis and down-regulating cytokinin degradation gene. Our results indicated that elevated CO 2 had differential promotive effects on crown and lateral root growth in tall fescue under low and moderate nitrate conditions in association with the regulation of endogenous auxin and cytokinin metabolism. • Elevated CO 2 had differentially positive effects on fibrous root characteristics under different nitrate supply. • Elevated CO 2 -regulated root growth under moderate nitrate was related with the endogenous auxin and cytokinin metabolism. • Elevated CO 2 -induced the higher IAA content was mainly attributed to the up-regulation of IAA synthesis gene. • Elevate CO 2 caused iPA accumulation by the up-regulation of synthesis gene and the down-regulation of degradation gene.

Effects of different fertilization sources on Olea europaea (Oleraceae)

This review highlights the importance of olive trees growing in the southwest of Buenos Aires, Argentina. It also discusses the importance (1) of the different fertilizations forms in the determination of the various soil physicochemical and leaf chemical properties, olives yield, oil yield and quality, and (2) oil quality parameters. Cover crops can be beneficial to soil properties. The incorporation of organic manures is also beneficial to improve plant and soil physical and biological properties, which allows a better root development and longevity, and nutrient absorption. Additionally, organic crops can increase the oil yield and quality in comparison to non-organic treatments. Foliar fertilization can be a very efficient system for supplying N, P and K to olive trees. However, several applications are required to meet the needs of the crop. Olive yield decreases significantly when soil fertilization with N is eliminated for several consecutive years in comparison to the fertilization that is carried out annually. Nutrient overfertilizationcan lead to several negative effects from the environmental point of view. Fertilization with P might be unnecessary due to the extensive root system of the olive trees. Olive have a high K requirement since large amounts of K are removed each year at harvest. However, fertilization with different levels of K had negligible effects on oil quality. Oil quality parameters were first associated with N concentrations in leaves and fruits. The phenolic content of the oil decreased linearly in relation to the increase of N in the leaves, which indicates a competition between the synthesis of proteins and the phenolic compounds.

Biological Flora of Coastal Wetlands: Sporobolus spartinus (Trin.) P.M. Peterson & Saarela

Stalter, R. and Lonard, R.I., 2022. Biological flora of coastal wetlands: Sporobolus spartinus (Trin.) P.M. Peterson & Saarela. Journal of Coastal Research, 38(6), 1231–1235. Coconut Creek (Florida), ISSN 0749-0208. Sporobolus spartinus (Trin.) P.M. Peterson & Saarela = Spartina spartinae (Trin.) Merr. ex Hitchc. is a New World temperate, subtropical, and tropical wetland species that often forms monotypic stands in intermittently flooded brackish marshes or in saline prairies that are flooded periodically. It is a densely cespitose perennial that tolerates salinities ranging from 3.5 to 44 psu. The water table at these sites is 10 to 30 cm below the surface and can be flooded up to 14 cm above the soil surface. Also known as gulf cordgrass or sacahuista, its extensive fibrous root system makes this species an excellent choice to prevent erosion and to protect the land from storm surges. The southern cordgrass community provides habitats for endangered whooping cranes and ocelots in Texas and habitats for Lower Keys marsh rabbits in Florida.

Strategic management of contaminated water bodies: Omics, genome-editing and other recent advances in phytoremediation

Due to excessive industrialization, urbanization and rising level of pollutants, the water bodies are continuously exposed to diverse group of toxic pollutants whose concentration, chemical forms and bioavailability in the aqueous system are governed by natural geochemical cycles as well as human activities. Chemical form or species of these toxic compounds or heavy metals is governed by the prevailing specific physical and chemical parameters like pH, salinity, dissolved organics, hardness and sedimentary load which impacts their mobility, bio-availability and hence toxicity. To overcome the challenging situation, an increased emphasis has been given on in-situ innovative technologies like phytoremediation, capable of detoxification of contaminated water bodies. The use of inherent aquatic plants along with recent omics tools can improve their phytoremediation ability to a great extent. These plants have an extensive root system which can filter and immobilize sediments, contaminants, fertilizer and pesticide run-off thereby reducing water pollution. Thus, the assortment and improvement of plants phytoremediation ability using the modern biotechnological tools and techniques, can be a suitable approach for successful remediation of contaminated water bodies. This review article focuses on the different biotechnological strategems like omics, proteomics, genomics, metabolomics and CRISPR in order to ameliorate the phytoremediation potential of the aquatic plants. The recent ground-breaking advancements to achieve desired genetic modification uses, CRISPR technology, to transfer a target set of genes to be assimilated into the plant genome of interest. Two variants of this technology, i.e. CRISPR-Cas9 as well as CRISPR-Cpf1 can be used for producing knock-outs, making gene substitutions, and targeting transcription and its regulation in the particular plant genome, to improve its phytoremediation efficiency.

The greenest revolution – harnessing the power of plants to help combat climate change

As we continue searching for the technologies that will halt global warming, let us take a moment to think about plants. A key contributor to our climate crisis is the accumulation of carbon dioxide in the atmosphere. Plants have been capturing carbon dioxide for billions of years, making them the most tried and tested carbon capture machinery on the planet. Plants fix carbon dioxide as part of photosynthesis. After years of research, we now know the key regulators of this process and have the knowledge to start engineering plants with increased photosynthetic capacity. In addition to improving the efficiency of carbon fixation, we must also find a way to stably store the carbon captured by plants. To achieve this, we can look to the below-ground part of the plant body – the root system. Plant roots are packed full of carbon and also exude carbon-rich molecules into the soil. Engineering future plants with deeper, more extensive root systems, with enhanced chemical composition that increases carbon content and reduces the rate of biodegradation, offers a way to store atmospheric carbon fixed by plants below ground for years to come. With optimized root systems, these plants would also be better equipped to explore their surrounding soils for water and nutrients, which would ultimately improve plant performance. This approach also offers a way to replenish our carbon-depleted soils, which would increase soil quality by improving water and nutrient retention. Harnessing the plants' natural ability to capture carbon, thus provides a way to not only restore balance to the carbon cycle, but also improve soil quality and future crop performance.

Rock fragment content in soils shift root foraging behavior in xerophytic species

Root traits associated with resource foraging, including fine-root branching intensity, root hair, and mycorrhiza, may change in soils that vary in rock fragment content (RFC), while how these traits covary at the level of individual root branching order is largely unknown. We subjected two xerophytic species, Artemisia vestita (subshrub) and Bauhinia brachycarpa (shrub), to increasing RFC gradients (0%, 25%, 50%, and 75%, v v− 1) in an arid environment and measured fine-root traits related to resource foraging. Root hair density and mycorrhizal colonization of both species decreased with increasing root order, but increased in third- or fourth-order roots at high RFCs (50% or 75%) compared to low RFCs. The two species tend to produce more root hairs than mycorrhizas under the high RFCs. For both species, root hair density and mycorrhizal colonization intensity were negatively correlated with root length and root diameter across root order and RFCs. Rockiness reduced root branching intensity in both species comparing with rock-free soil. At the same level of RFC, A. vestita had thicker roots and lower branching intensity than B. brachycarpa and tended to produce more root hairs. Our results suggest the high RFC soil conditions stimulated greater foraging functions in higher root orders. We found evidence for a greater investment in root hairs and mycorrhizal symbioses as opposed to building an extensive root system in rocky soils. The two species studied, A. vestita and B. brachycarpa, took different approaches to foraging in the rocky soil through distinctive trait syndromes of fine-root components.

The Invasion of the Land in Deep Time: Integrating Paleozoic Records of Paleobiology, Ichnology, Sedimentology, and Geomorphology

The invasion of the land was a complex, protracted process, punctuated by mass extinctions, that involved multiple routes from marine environments. We integrate paleobiology, ichnology, sedimentology, and geomorphology to reconstruct Paleozoic terrestrialization. Cambrian landscapes were dominated by laterally mobile rivers with unstable banks in the absence of significant vegetation. Temporary incursions by arthropods and worm-like organisms into coastal environments apparently did not result in establishment of continental communities. Contemporaneous lacustrine faunas may have been inhibited by limited nutrient delivery and high sediment loads. The Ordovician appearance of early land plants triggered a shift in the primary locus of the global clay mineral factory, increasing the amount of mudrock on the continents. The Silurian-Devonian rise of vascular land plants, including the first forests and extensive root systems, was instrumental in further retaining fine sediment on alluvial plains. These innovations led to increased architectural complexity of braided and meandering rivers. Landscape changes were synchronous with establishment of freshwater and terrestrial arthropod faunas in overbank areas, abandoned fluvial channels, lake margins, ephemeral lakes, and inland deserts. Silurian-Devonian lakes experienced improved nutrient availability, due to increased phosphate weathering and terrestrial humic matter. All these changes favoured frequent invasions to permament establishment of jawless and jawed fishes in freshwater habitats and the subsequent tetrapod colonization of the land. The Carboniferous saw rapid diversification of tetrapods, mostly linked to aquatic reproduction, and land plants, including gymnosperms. Deeper root systems promoted further riverbank stabilization, contributing to the rise of anabranching rivers and braided systems with vegetated islands. New lineages of aquatic insects developed and expanded novel feeding modes, including herbivory. Late Paleozoic soils commonly contain pervasive root and millipede traces. Lacustrine animal communities diversified, accompanied by increased food-web complexity and improved food delivery which may have favored permanent colonization of offshore and deep-water lake environments. These trends continued in the Permian, but progressive aridification favored formation of hypersaline lakes, which were stressful for colonization. The Capitanian and end-Permian extinctions affected lacustrine and fluvial biotas, particularly the invertebrate infauna, although burrowing may have allowed some tetrapods to survive associated global warming and increased aridification.

Phytoremediation of Heavy-Metals-Contaminated Soils: A Short-Term Trial Involving Two Willow Species from Gloucester WillowBank in the UK

Phytoremediation, as a bioremediation process in which plants are used to remove contaminants from an environment, has proved to be a practical and low-cost strategy for recovering mining-affected areas. This study aims to assess the potential for use in phytoremediation of two willow species, Salix viminalis and Salix dasyclados, by testing their potential for cleaning-up a range of soils with differing heavy metal concentrations: Pb (111, 141, 192 and 249 mg /kg), Zn (778.6, 1482, 2734 and 4411 mg/kg) and Cd (3.00, 5.03, 9.14 and 16.07 mg/kg). The extracted metals were preferentially translocated to the leaves with considerably higher concentrations and relative BAFs in the case of S. viminalis. The highest recorded Zn concentration of over 0.5% was found in the leaves of S. viminalis growing in soil 4. However, under the conditions of the experiments, S. dasyclados showed greater potential for use in phytoremediation, especially if coupled with use of biomass for energy production. An assessment of the suitability of willow species in this role, with regard to wider aspects involved, such as use of resultant biomass and/or waste management, revealed good potential. Willows are fast growing, grow vigorously from coppiced stumps and have extensive root systems. Therefore, their use in bioenergy production through pyrolysis or combustion, coupled with flue gas screening, is strongly advised.

Influence of treatment on rooting of arctic Salix species cuttings for revegetation

ABSTRACT Increased northern exploration and resource extraction highlight a need for effective revegetation techniques to restore disturbed environments. This study assessed effects of indole-3-butyric acid (IBA), water extracts of Salix and smoke, soaking time, and collection time on adventitious and lateral root development of Salix species cuttings collected from Diavik Diamond Mine Inc., Northwest Territories. Over 80 percent of fall and spring cuttings developed adventitious roots, yet only 30 percent of summer cuttings rooted, indicating strong seasonal influences. Many cuttings developed extensive root system architecture in 60 days; some developed up to six orders of roots. Root length decreased with increasing root order in all seasons, and season influenced length within root orders. Application of IBA increased number of primary roots per cutting per season and number of cuttings with less than fifty secondary roots per primary root. Longer soaking times increased number of primary roots per cutting in different seasons, and soaking up to ten days increased longest root length. Salix and smoke water extract applications increased number of cuttings with twenty-five to seventy-four secondary roots. This research highlights the importance of treatment effects on adventitious and lateral root development to optimize root system architecture of cuttings from northern shrub species.

Significance of sesame (Sesamum indicum L.) as a feed resource towards small-ruminant animal production in Southern Africa: a review.

Sesamum indicum (sesame) is a small seed legume, which is of nutritional and medicinal value to livestock. Sesame is a legume with positive attributes that include drought tolerance (owing to its extensive rooting system), low input demand for growth, and reduction of soil nematodes (in crop rotation systems). Attention in research has been shifted towards usage of sesame as human food to exploitation as livestock feed because of its high levels in crude protein (CP), minerals, amino acids, and polyunsaturated fatty acids (PUFAs). However, it is underutilized as a livestock feed resource in Southern Africa. In recent years, there has been increasing interest to cultivate the crop in Southern African countries through non-governmental organizations (NGOs) initiatives. The focus of such initiatives has been mainly production without value addition of the seed. At present in Southern Africa, widespread adoption of feeding strategies based on sesame has been restricted mainly due to lack of knowledge on production, marketing and value addition, availability of the seed, and technology adoption. Technology adoption is often limited specifically when oil extraction is considered, where by-products such as the meal are useful in animal production. This paper reviews the potential use of sesame to improve growth rates, feed intake, carcass qualities, meat quality, milk quality, milk yield, and blood metabolite levels of small ruminants. Production potential, economic feasibility, and strategies of using sesame in small-ruminant feeding programs are also outlined.

Establishing three warm-season turfgrasses with tailored water: II. Root development, nitrate accumulation in plant tissue and soil, and relationship with leaching.

Greenhouse experiments were conducted in 2015 and 2017 to assess the feasibility of establishing three warm-season grasses-buffalograss [Buchloe dactyloides (Natt.) Eng.] 'SWI 2000', inland saltgrass (Distichlis spicata L.), and bermudagrass (Cynodon dactylon L.) 'Princess77'-with tailored water (tertiary treated effluent with 15mg L-1 of NO3 -N) and to examine the impact on nitrate accumulation in soils and plant tissue and on root development. Grasses were established from seed in a loamy sand and irrigated with either tailored or potable water plus granular Ca(NO3 )2 fertilizer. Leachate collected at 10- and 30-cm depths was analyzed for NO3 -N and electrical conductivity. Root samples were collected to measure root length density (RLD) and root surface area (RSA). Weekly clippings were collected to determine total clipping yield and measure N content. Generally, there was no difference in establishment, RLD, or RSA between the two irrigation treatments. Highest RLD values were reported for bermudagrass, followed by buffalograss and inland saltgrass. Correlation analyses suggest that nitrate levels in leachate were lower in faster-growing grasses and in grasses with more extensive root systems, compared with slower-growing grasses with less roots, regardless of fertilization treatment. Total N in clippings was highest in inland saltgrass and lower in buffalograss and bermudagrass, indicating that N was limiting for faster-growing grasses. More research is needed to determine optimal N rates for establishing grasses that both optimize growth and minimize nitrate leaching.

Comparing the deep root growth and water uptake of intermediate wheatgrass (Kernza®) to alfalfa

AimsPerennial crops with more extensive and deep root systems could access deep stored water and build resilience to water shortage. In the context of human nutrition, perennial grain crops are very interesting. However, it is still questionable whether they are effective in using subsoil water. We compared intermediate wheatgrass (Kernza®) Thinopyrum intermedium, a perennial grain crop, to alfalfa Medicago sativa, a forage crop, for subsoil root growth and water uptake. Alfalfa was chosen because of its deep root system and agronomical interest as a companion crop.MethodsUsing TDR sensors, deuterium tracer labelling, minirhizotrons and the Hydrus-1D model we characterised the root distribution and water uptake patterns of these two perennial crops during two cropping seasons under field conditions down to 2.5 m soil depth.ResultsBoth crops grew roots down to 2.0 m depth that were active in water uptake but alfalfa was deeper rooted than intermediate wheatgrass. All experimental methods concluded that alfalfa used more water from below 1.0 m depth than intermediate wheatgrass. However, simulations predicted that intermediate wheatgrass used more than 20 mm of water after anthesis from below 1 m soil depth. Simulations confirmed the advantage of deep roots in accessing deep soil water under drought.ConclusionsIn regions with high groundwater recharge, growing deep-rooted perennial crops have great potential to exploit deep soil water that is often left unused. However, the road to a profitable perennial grain crop is still long and breeding intermediate wheatgrass (Kernza®) cultivars for increased root growth at depth seems to be a worthy investment for the development of more drought tolerant cultivars.

High‐yielding forage grass cultivars increase root biomass and soil organic carbon stocks compared with mixed‐species permanent pasture in temperate soil

AbstractAgricultural grass cultivars bred for increased forage yield commonly have extensive root systems. As roots are an important input of organic matter into the soil, it follows that such cultivars could lead to important increases in soil organic carbon (SOC), but this, and the mechanisms involved, are poorly understood with little empirical field evidence. We assessed the effect of two cultivars, Lolium perenne L. cv. “AberMagic” and L. perenne L. × Festuca pratensis Huds. cv. “Prior”, in comparison with mixed‐species permanent pasture (“Pasture”) in a field experiment on temperate alluvial soil in the southwest UK. Root and SOC stocks, and specific plant‐derived lipids as mechanistic biomarkers for shoot and root inputs of C, were measured on intact 1‐m volumetric soil cores collected on four dates in 2013–2015. Total grass yields were greater for both grass cultivars (40–43 Mg ha−1) than Pasture (39 Mg ha−1), and by 2015 root stocks in the upper 0.1 m were significantly greater by more than 4.7 Mg ha−1. At 0.1–0.3 m depth, SOC stocks (per 0.1‐m depth) were significantly greater under the two grass cultivars (24–50 Mg ha−1) compared to Pasture (18–32 Mg ha−1). In the full 1‐m profile, mean SOC stocks were 137, 133 and 110 Mg ha−1 for AberMagic, Prior and Pasture, respectively, matching root biomass distribution. Odd‐chain n‐alkane concentrations were significantly greater for shoots than roots (274 vs. 64 mg kg−1, respectively), and roots had significantly greater concentrations than shoots of even‐chain hydroxy fatty acids (1829 vs. 305 mg kg−1, respectively) and diacids (317 vs. 93 mg kg−1, respectively). This confirmed lipids as candidate biomarkers for distinguishing shoot and root inputs into the soil, with roots being the dominant source of SOC. Based on the observations of increased forage yield and SOC stock, high‐yielding forage grass cultivars can contribute to future strategies for climate‐smart agriculture in grassland‐dominated temperate regions.Highlights Selected root traits for increased depth, density and diameter may increase SOC in grassland. The effect of two high‐yielding forage grass cultivars were assessed in a field trial. Fast‐growing, high‐yielding cultivars enhanced root and SOC stocks compared to typical pasture. Lipid biomarkers confirmed that root inputs were the predominant C input to soil.

How Waterlogged Conditions Influence the Nitrogen Dynamics in a Soil–Water–Plant System: Implications for Wetland Restoration

Growing populations and industrialization have led to increased nitrogen (N) loads in wetland ecosystems. A micro-constructed wetland planted with Lythrum salicaria L. to treat artificial wastewater was used to investigate the short-term variations in the plant biomass and dynamics of total nitrogen (TN) content. Our results showed that the biomass of Lythrum salicaria L. rapidly increased during the experiment due to their extensive root system and vigorous spread, and waterlogged conditions had little effect on the relationship between biomass and the TN content in soil and effluent. Under different waterlogged conditions, the TN removal rates in the water were all greater than 60%, providing a reference for the waterlogged conditions used in wetland eutrophication restoration.

Rhizobium rhizogenes-mediated root proliferation in Cd/Zn hyperaccumulator Sedum alfredii and its effects on plant growth promotion, root exudates and metal uptake efficiency

In this study, Rhizobium rhizogenes-mediated root proliferation system in Sedum alfredii has been established. Twenty strains of R. rhizogenes were screened for root proliferation. A significant difference (P < 0.01) was observed in plant morphological characters under influence of different bacterial strains. The highest root fresh weight (3.236 g/plant) was observed with strain AS12556. Furthermore, significant difference (P < 0.05) was observed in the chemical composition of organic acids, Tartaric acid (TA), Succinic acid (SA), Malic acid (MA), Citric acid (CA) and Oxalic acid (OA), pH, Total Nitrogen (TN), Total Organic Carbon (TOC) and soluble sugars in root exudates with different R. rhizogenes mediated roots. Furthermore, a series of hydroponics experiments were conducted with varying concentrations of Cd (25, 50 and 75 µM) and Zn (100, 200 and 500 µM) to assess the phytoextraction efficiency of proliferated roots with Rhizobium. Several plants with proliferated roots showed enhanced growth and improved metal extraction efficiency. Five strains (LBA 9402, K599, AS12556, MSU440 and C58C1) were identified as potential strains for root proliferation in Sedum alfredii. R. rhizogenes strain AS12556 improved Cd/Zn phytoextraction by exogenous production of phytochemicals to promote root proliferation, improved shoot biomass, lowered oxidative damage and enhanced phytoextraction efficiency in S. alfredii. Therefore, it has been selected as a potential microbial partner of S. alfredii to develop extensive rooting system for better growth and enhanced phytoremediation potential. Results suggest that R. rhizogenes mediated root proliferation system can be used for optimizing metal extraction from contaminated soils.

Chemical characteristics of soil organic matter from integrated agricultural systems in southeastern Brazil

AbstractSoil organic matter (SOM) plays an essential role in agronomic systems and is of great importance to environmental sustainability and carbon sequestration. This study evaluates the accumulation of carbon in soils from integrated agricultural systems (S) that include crop (C), livestock (L), and forest (F) components (in different combinations: CLFS, LFS and CLS) and an undisturbed native forest (NF) as a reference area. The study sites are part of the Embrapa Pecuária Sudeste research station located in the southeast of Brazil in a region of dystrophic Red‐Yellow Latosol soils. Stable carbon isotopic analysis (δ13C) and solid‐state 13C nuclear magnetic resonance (13C NMR) spectroscopy were used to evaluate the chemical characteristics of humic acid (HA) extracts of soils from different soil horizons. The findings were discussed in the context of laser‐induced fluorescence spectroscopy (LIFS) measurements on the whole soils and carbon content on both the whole soils and HA extracts. With increasing depth of the soil horizons, bulk SOM (in the whole soil) and a more recalcitrant humic fraction (the HA) became enriched in carbon, indicative of accumulation. Isotopic analysis revealed that SOM in the crop‐livestock‐forest system exhibited δ13C signatures corresponding to C4 plants (grass and corn). The native forest exhibited a uniform δ13C signature characteristic of C3 plants (native trees). Benzenepolycarboxylic acids (BPCA) quantification on limited samples revealed condensed aromatic structures in both crop‐livestock‐forest system and native forest. The absence of burning suggests that these compounds come from the humification of lignin. Based on structural characterization, carbon is sequestered as recalcitrant and long‐lived oxidized ligninaceous structures and condensed aromatic groups. The current research demonstrates the feasibility of novel agricultural approaches such as using crop‐livestock‐forest systems. Such pastureland management enhances higher agricultural productivity and sustainability, thus avoiding new deforestation of native areas.Highlights Integrated agricultural systems enhance carbon enrichment in soil organic matter and humic acids. Carbon stabilized in oxidized ligninaceous and condensed molecules promotes long‐term carbon storage. Extended root systems are likely to play a critical role in carbon sequestration. Integrated agricultural systems can be effective alternatives for reducing greenhouse gases.