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1.
Yuliya V. Kuzmicheva Aleksander I. Shaposhnikov Svetlana N. Petrova Natalia M. Makarova Irina L. Tychinskaya Jan V. Puhalsky Nikolay V. Parahin Igor A. Tikhonovich Andrey A. Belimov 《Plant and Soil》2017,413(1-2):83-95
Aims
It has been increasingly recognized that only distal lower order roots turn over actively within the <2 mm fine root system of trees. This study aimed to estimate fine root production and turnover rate based on lower order fine roots and their relations to soil variables in mangroves.Methods
We conducted sequential coring in five natural mangrove forests at Dongzhai Bay, China. Annual fine root production and turnover rate were calculated based on the seasonal variations of the biomass and necromass of lower order roots or the whole fine root system.Results
Annual fine root production and turnover rate ranged between 571 and 2838 g m?2 and 1.46–5.96 yr?1, respectively, estimated with lower order roots, and they were increased by 0–30 % and reduced by 13–48 %, respectively, estimated with the whole fine root system. Annual fine root production was 1–3.5 times higher than aboveground litter production and was positively related to soil carbon, nitrogen and phosphorus concentrations. Fine root turnover rate was negatively related to soil salinity.Conclusions
Mangrove fine root turnover plays a more important role than aboveground litter production in soil C accumulation. Sites with higher soil nutrients and lower salinity favor fine root production and turnover, and thus favor soil C accumulation.2.
Janneke M. Ravenek Liesje Mommer Eric J. W. Visser Jasper van Ruijven Jan Willem van der Paauw Annemiek Smit-Tiekstra Hannie de Caluwe Hans de Kroon 《Plant and Soil》2016,401(1-2):39-50
Background and aims
Measures of phosphorus (P) in roots recovered from soil underestimate total P accumulation below-ground by crop species since they do not account for P in unrecovered (e.g., fine) root materials. 33P-labelling of plant root systems may allow more accurate estimation of below-ground P input by plants.Methods
Using a stem wick-feeding technique 33P-labelled phosphoric acid was fed in situ to canola (Brassica napus) and lupin (Lupinus angustifolius) grown in sand or loam soils in sealed pots.Results
Recovery of 33P was 93 % in the plant-soil system and 7 % was sorbed to the wick. Significantly more 33P was allocated below-ground than to shoots for both species with 59–90 % of 33P measured in recovered roots plus bulk and rhizosphere soil. 33P in recovered roots was higher in canola than lupin regardless of soil type. The proportion of 33P detected in soil was greater for lupin than canola grown in sand and loam (37 and 73 % lupin, 20 and 23 % canola, respectively). Estimated total below-ground P accumulation by both species was at least twice that of recovered root P and was a greater proportion of total plant P for lupin than canola.Conclusion
Labelling roots using 33P via stem feeding can empower quantitative estimates of total below-ground plant P and root dry matter accumulation which can improve our understanding of P distribution in soil-plant systems.3.
Background and Aims
Rock fragments within topsoil have important effects on soil properties and plant growth. This study mainly aimed to investigate the relationships between rock fragments, soil carbon (C) and nitrogen (N) densities and vegetation biomass in an alpine steppe.Methods
Rock fragments, plant and soil samples were collected from four topographic positions (top, upper, lower, and bottom) on a hillslope.Results
Volumetric rock fragment content within the 0–30 cm soil profile varied from 17.8 to 30.5%, the upper position value was significantly greater (P < 0.05) than those at other positions. The highest aboveground biomass was observed at the lower position (921 kg ha?1), while the highest belowground biomass within the 0–30 cm profile was found at the upper position (4460 kg ha?1). More fine earth and plant litter input accompanied by lower C and N losses induced by rainfall erosion resulted in higher soil organic C and total N densities (28.6 Mg C ha?1 and 2.87 Mg N ha?1) at the lower position.Conclusions
Rock fragments may promote root growth but limit aboveground biomass production, and can therefore change the biomass distribution pattern. Our findings provide more evidence for scientifically assessing alpine steppe productivity.4.
Timothy I. McLaren Michael J. McLaughlin Therese M. McBeath Richard J. Simpson Ronald J. Smernik Christopher N. Guppy Alan E. Richardson 《Plant and Soil》2016,401(1-2):23-38
Background and aims
Single superphosphate (SSP) is a major source of phosphorus (P) used in grazing systems to improve pasture production. The aim of this experiment was to determine the fate of fertiliser P in clover pastures under field conditions.Methods
A procedure was developed to radiolabel SSP granules with a 33P radiotracer, which was then applied to the soil surface (equivalent to ~12 kg P ha?1) of a clover pasture. Recovery of fertiliser P was determined in clover shoots, fertiliser granules and soil fractions (surface layer: 0–4 cm and sub-surface layer: 4–8 cm).Results
The P diffusion patterns of the 33P-labelled SSP granules were not significantly different to those of commercial SSP granules (P?>?0.05). Recovery of fertiliser P in clover shoots was 30–35 %. A considerable proportion of the fertiliser P (~28 %) was recovered in the surface soil layer and was largely inorganic P.Conclusions
Recovery of fertiliser P by clover plants was up to 35 % in the year of application. Much of the fertiliser P in soil fractions was inorganic P, which highlights the importance of inorganic P forms and dynamics in soils under clover pasture on a single season timeframe at these sites.5.
C. Meneses T. Gonçalves S. Alquéres L. Rouws R. Serrato M. Vidal J. I. Baldani 《Plant and Soil》2017,412(1-2):133-142
Aims
Increasing the input and turnover of root tissue is considered to be one method that may increase carbon (C) inputs and storage in soil. The use of herbicide during pasture renewal (periodic re-sowing of pasture) is expected to increase root inputs and turnover as plants die. The objective of this study was to quantify the short-term impact of pasture renewal on root turnover and C input to soil of ryegrass-clover pastures.Methods
Pastures were labelled in the field using a 13C isotope pulse labelling method within 1 m2 clear chambers. Five daily labelling events were carried out during one week in paired treatment plots within 3 replicate paddocks. One plot per paddock was sprayed with herbicide and then the pasture was renewed by direct drilling of seed. The 13C of roots and soil (0–100 mm) was measured at regular intervals over an 89-day period.Results
Herbicide application caused an initial rapid turnover time of 17 days followed by a slower turnover time of 524 days, compared to unsprayed pasture which had a root turnover of 585 days. Faster root turnover following herbicide application resulted in greater cumulative C input to soil over 89 days with approximately double the C input in the sprayed treatment (3238 ± 378 kg C ha?1) compared to the unsprayed treatment (1726 ± 540 kg C ha?1).Conclusions
The use of glyphosate during pasture renewal increased root turnover and resulted in a greater short term cumulative C input to soil. This study provides the first values of root turnover and C input to soil during a pasture renewal event in New Zealand pasture systems and contributes to the understanding of how pasture roots may influence the soil C input following plant death in grassland systems.6.
Robert P. Jeffery Richard J. Simpson Hans Lambers Daniel R. Kidd Megan H. Ryan 《Plant and Soil》2017,412(1-2):21-34
Aims
Trifolium subterraneum L. is the predominant annual pasture legume in southern Australia. Cultivars with improved phosphorus (P) foraging ability would improve the P-use efficiency of agricultural systems. We therefore investigated variation in root traits related to P-uptake among six cultivars.Methods
Micro-swards were grown at six levels of P in field soil with indigenous arbuscular mycorrhizal (AM) fungi for six weeks. Dry matter yield, tissue P concentration, rhizosphere carboxylates, AM fungal colonisation and root morphological traits were measured.Results
The cultivars showed similar shoot and root yield responses to P supply. Average root diameter did not change, specific root length (SRL) increased and root tissue density (RTD) decreased with increased P supply. Amounts of total rhizosphere carboxylates were low (<1.2 nmol cm?1 root). The percentage of root length colonised by AM fungi was greatest (29–43 %) at an intermediate level (8 mg kg?1 dry soil) of P supply.Conclusions
Most differences among cultivars were reasonably consistent across P supply levels, indicating greater numbers of lines could be screened reliably at a single P level. Low colonisation by AM fungi at low P supply deserves consideration when selecting soils for cultivar comparisons. Increased SRL and decreased RTD at high P supply likely result from self-shading within the micro-swards and warrant further investigation.7.
Opportunities for mobilizing recalcitrant phosphorus from agricultural soils: a review 总被引:3,自引:0,他引:3
Daniel Menezes-Blackburn Courtney Giles Tegan Darch Timothy S. George Martin Blackwell Marc Stutter Charles Shand David Lumsdon Patricia Cooper Renate Wendler Lawrie Brown Danilo S. Almeida Catherine Wearing Hao Zhang Philip M. Haygarth 《Plant and Soil》2018,427(1-2):5-16
Background
Phosphorus (P) fertilizer is usually applied in excess of plant requirement and accumulates in soils due to its strong adsorption, rapid precipitation and immobilisation into unavailable forms including organic moieties. As soils are complex and diverse chemical, biochemical and biological systems, strategies to access recalcitrant soil P are often inefficient, case specific and inconsistently applicable in different soils. Finding a near-universal or at least widely applicable solution to the inefficiency in agricultural P use by plants is an important unsolved problem that has been under investigation for more than half a century.Scope
In this paper we critically review the strategies proposed for the remobilization of recalcitrant soil phosphorus for crops and pastures worldwide. We have additionally performed a meta-analysis of available soil 31P–NMR data to establish the potential agronomic value of different stored P forms in agricultural soils.Conclusions
Soil inorganic P stocks accounted on average for 1006 ± 115 kg ha?1 (57 ± 7%), while the monoester P pool accounted for 587 ± 32 kg ha?1 (33 ± 2%), indicating the huge potential for the future agronomic use of the soil legacy P. New impact driven research is needed in order to create solutions for the sustainable management of soil P stocks.8.
Aims
We evaluated the efficacy of biochar application for suppressing bacterial wilt of tomato and identified the potential underlying mechanisms involved in the disease control.Methods
We measured the impact of two different sized biochar (53–120 μm and 380–830 μm) on bacterial wilt incidence in a greenhouse experiment. The efficiency of different sized biochar for the adsorption of tomato root exudates and the pathogen was further examined in vitro. We also quantified the effects of biochar and tomato root exudates on two pathogen virulence factors, chemotaxis, swarming motility and examined the effect of biochar on pathogen root colonization.Results
Fine biochar application (3%; w:w) significantly decreased the bacterial wilt incidence by 19.9%. Biochar with different particle size had similar adsorption capacity for root exudates, while fine biochar was efficient (91%) in pathogen adsorption. Root exudates and fine biochar increased the chemotaxis ability of pathogen, while fine biochar reduced pathogen swarming motility and rhizosphere colonization.Conclusions
Application of fine biochar can significantly decreased bacterial wilt incidence. This was mechanistically explained by biochar ability to 1) adsorb pathogen directly and indirectly via adsorption of root exudates (based on pathogen chemotaxis) and to 2) directly suppress pathogen swarming motility and subsequent root colonization.9.
S. L. Bauke M. Landl M. Koch D. Hofmann K. A. Nagel N. Siebers A. Schnepf W. Amelung 《Plant and Soil》2017,416(1-2):67-82
Background and aims
Macropores may be preferential root pathways into the subsoil. We hypothesised that the presence of macropores promotes P-uptake from subsoil, particularly at limited water supply in surface soil. We tested this hypothesis in a rhizotron experiment with spring wheat (Triticum aestivum cv. Scirocco) under variation of fertilisation and irrigation.Methods
Rhizotrons were filled with compacted subsoil (bulk density 1.4 g cm?3), underneath a P-depleted topsoil. In half of these rhizotrons the subsoil contained artificial macropores. Spring wheat was grown for 41 days with and without irrigation and 31P–addition. Also, a 33P–tracer was added at the soil surface to trace P-distribution in plants using liquid scintillation counting and radioactive imaging.Results
Fertilisation and irrigation promoted biomass production and plant P-uptake. Improved growing conditions resulted in a higher proportion of subsoil roots, indicating that the topsoil root system additionally promoted subsoil nutrient acquisition. The presence of macropores did not improve plant growth but tended to increase translocation of 33P into both above- and belowground biomass. 33P–imaging confirmed that this plant-internal transport of topsoil-P extended into subsoil roots.Conclusions
The lack of penetration resistance in macropores did not increase plant growth and nutrient uptake from subsoil here; however, wheat specifically re-allocated topsoil-P for subsoil root growth.10.
Objectives
To evaluate the effects of 12 biotic and abiotic elicitors for increasing the production of plumbagin in Plumbago indica root cultures.Results
Most elicitors showed minimal effects on the root dry weight, except for 250 mg chitosan l?1 and 10 mM l-alanine that markedly decreased root biomass by about 40 % compared to the untreated root cultures (5 g l?1). Treatments with 100 µM AgNO3 significantly increased intracellular plumbagin production by up to 7.6 mg g?1 DW that was 4-fold more than the untreated root cultures (1.9 mg g?1 DW). In contrast, treatments with 150 mg chitosan l?1, 5 mM l-alanine, and 50 µM 1-naphthol significantly enhanced the extracellular secretion of plumbagin by up to 10.6, 6.9, and 5.7 mg g?1 DW, respectively, and increased the overall production of plumbagin by up to 12.5, 12.5, and 9.4 mg g?1 DW, respectively.Conclusions
Chitosan (150 mg l?1), l-alanine (5 mM), and 1-naphthol (50 µM) were the best elicitors to enhance plumbagin production in P. indica root cultures.11.
Bernhard Zehetgruber Johannes Kobler Thomas Dirnböck Robert Jandl Rupert Seidl Andreas Schindlbacher 《Plant and Soil》2017,420(1-2):239-252
Aims
Slow or failed tree regeneration after forest disturbance is increasingly observed in the central European Alps, potentially amplifying the carbon (C) loss from disturbance. We aimed at quantifying C dynamics of a poorly regenerating disturbance site with a special focus on the role of non-woody ground vegetation.Methods
Soil CO2 efflux, fine root biomass, ground vegetation biomass, tree increment and litter input were assessed in (i) an undisturbed section of a ~ 110 years old Norway spruce stand, (ii) in a disturbed section which was clear-cut six years ago (no tree regeneration), and (iii) in a disturbed section which was clear-cut three years ago (no tree regeneration).Results
Total soil CO2 efflux was similar across all stand sections (8.5 ± 0.2 to 8.9 ± 0.3 t C ha?1 yr.?1). The undisturbed forest served as atmospheric C sink (2.1 t C ha?1 yr.?1), whereas both clearings were C sources to the atmosphere. The source strength three years after disturbance (?5.5 t C ha?1 yr.?1) was almost twice as high as six years after disturbance (?2.9 t C ha?1 yr.?1), with declining heterotrophic soil respiration and the high productivity of dense graminoid ground vegetation mitigating C loss.Conclusions
C loss after disturbance decreases with time and ground vegetation growth. Dense non-woody ground vegetation cover can hamper tree regeneration but simultaneously decrease the ecosystem C loss. The role of ground vegetation should be more explicitly taken into account in forest C budgets assessing disturbance effects.12.
Background and aims
Layered profiles of designed soils may provide long-term benefits for green roofs, provided the vegetation can exploit resources in the different layers. We aimed to quantify Sedum root foraging for water and nutrients in designed soils of different texture and layering.Methods
In a controlled pot experiment we quantified the root foraging ability of the species Sedum album (L.) and S. rupestre (L.) in response to substrate structure (fine, coarse, layered or mixed), vertical fertiliser placement (top or bottom half of pot) and watering (5, 10 or 20 mm week?1).Results
Water availability was the main driver of plant growth, followed by substrate structure, while fertiliser placement only had marginal effects on plant growth. Root foraging ability was low to moderate, as also reflected in the low proportion of biomass allocated to roots (5–13%). Increased watering reduced the proportion of root length and root biomass in deeper layers.Conclusions
Both S. album and S. rupestre had a low ability to exploit water and nutrients by precise root foraging in substrates of different texture and layering. Allocation of biomass to roots was low and showed limited flexibility even under water-deficient conditions.13.
Heidi A. Waddell Richard J. Simpson Megan H. Ryan Hans Lambers Denys L. Garden Alan E. Richardson 《Plant and Soil》2017,412(1-2):7-19
Aims
Rytidosperma species are native Australian grasses which have different growth rates and phosphorus (P) requirements. This study examined the role of root morphology traits in response to P supply.Methods
Nine Rytidosperma species ranging from slow- to fast-growth were examined along with Lolium perenne and Bromus hordeaceus. Plants were grown in a glasshouse for 47 days in soil supplied with six levels of P between 0 and 60 mg P per pot. Root mass, length and diameter, root hair length and density, and extent of mycorrhizal colonisation were measured.Results
Across all species there was a positive correlation (P < 0.001) between P uptake and root mass, length and root hair cylinder volume (RHCV; estimated using root diameter, root hair length and root length) at all levels of P supply. An exception was the RHCV of B. hordeaceus, where expected P uptake was not achieved due to a markedly reduced root length at low-P supply. For the Rytidosperma species, morphological plasticity for specific root length, root mass fraction and root hair length ranged from 1.5-fold to 2.7-fold between high- and low-P supply. However, across all species and P levels no single root morphological trait was identified for universally increasing the size of the root system and P uptake.Conclusions
Fast-growing species took up more P as a result of an overall larger root mass, greater root length and larger RHCV.14.
Background and aims
In Australia’s Mediterranean hyperdiverse vegetation, species that produce cluster roots to mobilise poorly-available nutrients (e.g. Banksia spp.) are an important functional and structural component. Cluster roots are only active during the wet season, indicating a strong dependence on suitable surface soil moisture conditions. Winter rainfall in this region is declining due to global climate change, with a delayed commencement of rains and a decline in precipitation. It is unknown how lower soil moisture levels will affect the root dynamics of these globally-significant plant communities.Methods
We determined the root dynamics and root lifespan with minirhizotrons with or without irrigation to simulate reduced rainfall scenarios.Results
We found a major effect of irrigation on the early production (0.24 m m?2 d?1 increase), occurrence (97% increase) of cluster roots and only slight effects on lifespan (~10 days less) of all root types. With irrigation, the resultant greater soil moisture levels increased the deployment of cluster roots. Apart from cluster roots, the dynamics of other roots did not decline at lower soil moisture levels, suggesting that this system shows some resilience to decreased rainfall.Conclusions
Future research should focus on assessing if climate-altered cluster-root activity may be promoting compositional shifts in plant communities with additional restraining effects on root trait diversity.15.
Background and aims
In Malawi, strategies are being sought to boost maize production through improvements in soil fertility. This study assessed the impact of intercropping maize (Zea mays) with pigeon pea (Cajanus cajan) in Lixisols of Malawi on yield, biological N fixation, soil aggregation, and P forms within soil aggregates.Methods
Maize and pigeon pea were grown intercropped in pots, with varying degrees of root interaction in order to understand the relative importance of biochemical versus physical rhizospheric interactions. Following harvest, soils were separated into aggregate fractions using wet-sieving, and the nutrient content of all fractions was assessed.Results
The proportion of macroaggregates and microaggregates increased by 52 and 111%, respectively, in the intercropping treatment compared to sole maize, which significantly increased organic P storage in the microaggregates of intercropped compared to sole maize (84 versus 29 mg P kg?1, respectively). Biologically fixed N increased from 89% in the sole pigeon pea to 96% in the intercropped system.Conclusions
Intercropping maize with pigeon pea can have a significant and positive impact on soil structure as well as nutrient storage in these high P-sorbing soils. This is caused primarily by physical root contact and to a lesser degree by biochemical activities.16.
17.
Improving N management through intercropping alleviates the inhibitory effect of mineral N on nodulation in pea 总被引:7,自引:0,他引:7
Background and aims
Symbiotic N2 fixation is essential in the development of sustainable agriculture, but the nodulation of legumes is usually inhibited by N fertilization. Here, the intercropping of maize and pea in strips under various N managements was used as a means to alleviate the inhibitory effect of mineral N on pea nodulation and N2 fixation and to improve system performance.Methods
N natural abundance (δ 15N) analysis was employed to quantify N2 fixation in the 3 years (2012 to 2014) of field experiment in Hexi Corridor of Northwestern China. Four N management systems with N rate of 0 kg N ha?1 (the control), 90?+?45 kg N ha?1 (base N plus topdressing N), 90?+?90 kg N ha?1, and 90?+?135 kg N ha?1 were implemented in the maize/pea strip intercropping to form different ratios of base N to topdressing N.Results
Intercropped pea improved nodule biomass per plant by 99 %, increased nitrogen derived from the atmosphere (Ndfa) by 35 %, and promoted aboveground plant tissue N accumulation by 35 % as compared with sole pea, averaged across the four N treatments. Compared to the highest N fertilizer treatment, a reduction of topdressing to 45 kg N ha?1 increased the nodule biomass of intercropped pea by 116 %, Ndfa by 35 %, and grain yield by 6 %.Conclusions
Adaptation of suitable N management in cereal/legume intercropping systems will allow an effective conversion of atmospheric N2 into crop available N and thus maximizing the system productivity.18.
Marie J. Zwetsloot Johannes Lehmann Taryn Bauerle Steven Vanek Rachel Hestrin Abebe Nigussie 《Plant and Soil》2016,408(1-2):95-105
Aims
The objectives of this study were to evaluate (1) the fertilizer potential of bone char, (2) the effects of wood biochar on plant-available phosphorus (P), and (3) the role of root-mycorrhizae-biochar interactions in plant P acquisition from a P-fixing soil.Methods
Incubation and pot experiments were conducted with a P-fixing soil and maize with or without root hairs and arbuscular mycorrhizae (AM) inoculation. Olsen-, resin-P and plant P accumulation were used to estimate P availability from bone char, co-pyrolyzed bone char-wood biochar, and separate bone char and wood biochar additions produced at 60, 350 and 750 °C, and Triple Superphosphate (TSP).Results
Maize inoculated with AM showed similar P accumulation when fertilized with either 750 °C bone char or TSP. Pyrolyzing bone did not increase extractable P in soil in comparison to unpyrolyzed bone, apart from a 67 % increase in resin-extractable P after additions of bone char pyrolyzed at 350 °C. Despite greater Olsen-P extractability, co-pyrolysis of bone with wood reduced maize P uptake. Wood biochars reduced resin-P from bone char by 14–26 %, whereas oven-dried wood increased resin-P by 23 %.Conclusions
Bone char is an effective P fertilizer, especially if root-AM interactions are simultaneously considered. Biochar influences plant access to soil P and requires careful management to improve P availability.19.
Ellen L. Fry Amy L. Evans Craig J. Sturrock James M. Bullock Richard D. Bardgett 《Plant and Soil》2018,425(1-2):189-200
Aims
Fine root morphological traits are generally changed under soil nitrogen (N) enrichment, however, the underlying mechanism and functional significance are still not well understood. Our aims were to investigate the linkage of root morphology to anatomy, and its implication for root function at elevated soil N availability.Methods
Ingrowth cores were used to sample root tips (0–20 cm soil depth) from six temperate tree species growing in monoculture plantations at a common site in northeastern China. Root morphological and anatomical traits were concurrently measured, and their relationships were determined within and among species in both control and N fertilization (10 g N m?2y?1) plots.Results
Root diameter generally increased in all six species (non-significant for Phellodendron amurense) following N fertilization, which was caused by the increased root stele radius rather than cortical thickness. Congruently, N fertilization significantly decreased the ratio of cortical thickness to stele radius, but increased the ratio of total cross-sectional area of conduits to stele area in root tips across all species.Conclusions
The observed anatomical changes of root tips contributed to the alternations of morphological root traits following N fertilization, with potentially important impacts on root physiological functions, like increased water and nutrient transport.20.
Marcio Reis Martins Claudia Pozzi Jantalia Verônica Massena Reis Ingbert Döwich José Carlos Polidoro Bruno José Rodrigues Alves Robert Michael Boddey Segundo Urquiaga 《Plant and Soil》2018,422(1-2):239-250