Photosynthetic recovery in drought-rehydrated grapevines is associated with high demand from the sinks, maximizing the fruit-oriented performance.

To understand how grapevine sinks compete with each other during water stress and subsequent rehydration, carbon (C) allocation patterns in drought-rehydrated vines (REC) at the beginning of fruit ripening were compared with control vines maintained under drought (WS) or fully irrigated (WW). In the 30 days following rehydration, the quantity and distribution of newly fixed C between leaves, roots and fruits was evaluated through 13 CO2 pulse-labeling and stable isotope ratio mass spectrometry. REC plants diverted the same percentage of fixed C towards the berries as the WS plants, although the percentage was higher than that of WW plants. Net photosynthesis (measured simultaneously with root respiration in a multichamber system for analysis of gas exchange above- and below-ground) was approximately two-fold greater in REC compared to WS treatment, and comparable or even higher than in WW plants. Maximizing C assimilation and delivery in REC plants led to a significantly higher amount of newly fixed C compared to both control treatments, already 2 days after rehydration in root, and 2 days later in the berries, in line with the expression of genes responsible for sugar metabolism. In REC plants, the increase in C assimilation was able to support the requests of the sinks during fruit ripening, without affecting the reserves, as was the case in WS. These mechanisms clarify what is experienced in fruit crops, when occasional rain or irrigation events are more effective in determining sugar delivery towards fruits, rather than constant and satisfactory water availabilities.

Strigolactones affect phosphorus acquisition strategies in tomato plants.

Strigolactones (SLs) are plant hormones that modulate morphological, physiological and biochemical changes as part of the acclimation strategies to phosphorus (P) deficiency, but an in-depth description of their effects on tomato P-acquisition strategies under P shortage is missing. Therefore, in this study, we investigate how SLs impact on root exudation and P uptake, in qualitative and quantitative terms over time, in wild-type and SL-depleted tomato plants grown with or without P. Under P shortage, SL-depleted plants were unable to efficiently activate most mechanisms associated with the P starvation response (PSR), except for the up-regulation of P transporters and increased activity of P-solubilizing enzymes. The reduced SL biosynthesis had negative effects also under normal P provision, because plants over-activated high-affinity transporters and enzymatic activities (phytase, acidic phosphatase) to sustain elevated P uptake, at great carbon and nitrogen costs. A shift in the onset of PSR was also highlighted in these plants. We conclude that SLs are master kinetic regulators of the PSR in tomato and that their defective synthesis might lead both to suboptimal nutritional outcomes under P depletion and an unbalanced control of P uptake when P is available.

Ecological functions provided by dung beetles are interlinked across space and time: evidence from 15 N isotope tracing.

Maintaining multiple ecological functions ("multifunctionality") is crucial to sustain viable ecosystems. To date most studies on biodiversity-ecosystem functioning (BEF) have focused on single or few ecological functions and services. However, there is a critical need to evaluate how species and species assemblages affect multiple processes at the same time, and how these functions are interconnected. Dung beetles represent excellent model organisms because they are key contributors to several ecosystem functions. Using a novel method based on the application of 15 N-enriched dung in a mesocosm field experiment, we assessed the role of dung beetles in regulating multiple aspects of nutrient cycling in alpine pastures over appropriate spatial (up to a soil depth of 20 cm) and temporal (up to 1 yr after dung application) scales. 15 N isotope tracing allowed the evaluation of multiple interrelated ecosystem functions responsible for the cycling of dung-derived nitrogen (DDN) in the soil and vegetation. We also resolved the role of functional group identity and the importance of interactions among co-occurring species for sustaining multiple functions by focusing on two different dung beetle nesting strategies (tunnelers and dwellers). Species interactions were studied by contrasting mixed-species to single-species assemblages, and asking whether the former performed multiple functions better than the latter. Dung beetles influenced at least seven ecological functions by facilitating dung removal, transport of DDN into the soil, microbial ammonification and nitrification processes, uptake of DDN by plants, herbage growth, and changes in botanical composition. Tunnelers and dwellers were found to be similarly efficient for most functions, with differences based on the spatial and temporal scales over which the functions operated. Although mixed-species assemblages seemed to perform better than single-species, this outcome may be dependent on the context. Most importantly though, the different functions were found to be interconnected sequentially as reveled by analyzing 15 N content in dung, soil and vegetation. Taken together, our current findings offer strong support for the contention that the link between biodiversity and ecosystem functions should be examined not function by function, but in terms of understanding multiple functions and how they interact with each other.

Fertilization strategies affect phosphorus forms and release from soils and suspended solids.

The release of phosphorus from soils in surface runoff is strongly influenced by fertilizer inputs and contributes significantly to agriculturally driven eutrophication. This work evaluated the forms and availability of P in bulk soils and suspended solids (SS) produced by a water dispersion test that mimics the action of rain events and/or irrigation. This test was applied on soils cultivated with maize and fertilized with mineral N, P, and K (NPK); mineral P and K (PK); bovine slurry and P (S); or manure and P (M) for 15 yr. The P surplus in the treated soils was in the order NPK < PK < S < M. Forms and availability of P were analyzed in bulk soils, and their respective SS (<20 µm) by the Hedley sequential P fractionation method and the isotopic exchange kinetics. The labile forms increased according to P surplus and represented up to 15 and 25% of total P in the bulk soil and in the SS, respectively, indicating a selective enrichment of the more labile P forms in the erodible particles. Exchangeability of P from SS was rapid and intense as a result of a shift of P solution equilibrium at the increased water/solid ratio and a larger accumulation of more labile P in the detached particles than in the bulk soil. Phosphorus saturation of iron and aluminum oxides and the enrichment of fertilizer-derived P salts in the suspended solids control P forms and exchangeability for mineral fertilizer treatments, whereas in M soil carbon content assumed a key role.

Dynamic microbial community associated with iron-arsenic co-precipitation products from a groundwater storage system in Bangladesh.

The prokaryotic community in Fe-As co-precipitation product from a groundwater storage tank in Bangladesh was investigated over a 5-year period to assess the diversity of the community and to infer biogeochemical mechanisms that may contribute to the formation and stabilisation of co-precipitation products and to Fe and As redox cycling. Partial 16S rRNA gene sequences from Bacteria and Archaea, functional markers (mcrA and dsrB) and iron-oxidising Gallionella-related 16S rRNA gene sequences were determined using denaturing gradient gel electrophoresis (DGGE). Additionally, a bacterial 16S rRNA gene library was also constructed from one representative sample. Biogeochemical characterization demonstrated that co-precipitation products consist of a mixture of inorganic minerals, mainly hydrous ferric oxides, intimately associated with organic matter of microbial origin that contribute to the chemical and physical stabilisation of a poorly ordered structure. DGGE analysis and polymerase chain reaction-cloning revealed that the diverse bacterial community structure in the co-precipitation product progressively stabilised with time resulting in a prevalence of methylotrophic Betaproteobacteria, while the archaeal community was less diverse and was dominated by members of the Euryarchaeota. Results show that Fe-As co-precipitation products provide a habitat characterised by anoxic/oxic niches that supports a phylogenetically and metabolically diverse group of prokaryotes involved in metal, sulphur and carbon cycling, supported by the presence of Gallionella-like iron-oxidizers, methanogens, methylotrophs, and sulphate reducers. However, no phylotypes known to be directly involved in As(V) respiration or As(III) oxidation were found.

Pyoluteorin Produced by the Biocontrol Agent Pseudomonas protegens Is Involved in the Inhibition of Heterobasidion Species Present in Europe.

Pseudomonas protegens (strain DSMZ 13134) is a biocontrol agent with promising antagonistic activity hinging on antibiosis against the fungal forest pathogens Heterobasidion spp. Here, by using High-Performance Liquid Chromatography coupled to Mass Spectrometry (HPLC-MS), we assessed whether monocultures of P. protegens (strain DSMZ 13134) produce the three major determinants of biocontrol activity known for the genus Pseudomonas: 2,4-diacetylphloroglucinol (2,4-DAPG), pyoluteorin (PLT), and pyrrolnitrin (PRN). At the tested culture conditions, we observed the production of PLT at concentrations ranging from 0.01 to 10.21 mg/L and 2,4-DAPG at a concentration not exceeding 0.5 mg/L. Variations of culture conditions involving culture medium, incubation temperature, and incubation period had no consistent influence on PLT production by the bacterium. Assays using culture medium amended with PLT at the same concentration of that present in cell-free filtrate of the bacterium, i.e., 3.77 mg/L, previously documented as effective against Heterobasidion spp., showed a remarkable activity of PLT against genotypes of all the four Heterobasidion species present in Europe, including the non-native invasive H. irregulare. However, such antifungal activity decreased over time, and this may be a constraint for using this molecule as a pesticide against Heterobasidion spp. When the bacterium was co-cultured in liquid medium with genotypes of the different Heterobasidion species, an increased production of PLT was observed at 4 °C, suggesting the bacterium may perform better as a PLT producer in field applications under similar environmental conditions, i.e., at low temperatures. Our results demonstrated the role of PLT in the inhibition of Heterobasidion spp., although all lines of evidence suggest that antibiosis does not rely on a single constitutively produced metabolite, but rather on a plethora of secondary metabolites. Findings presented in this study will help to optimize treatments based on Pseudomonas protegens (strain DSMZ 13134) against Heterobasidion spp.

Impact of Legumes as a Pre-Crop on Nitrogen Nutrition and Yield in Organic Greenhouse Tomato.

An organic greenhouse crop of tomato was established in February following cultivation of cowpea (CP) or common bean (CB) for green pod production, or faba bean (FB) for green manuring. The vegetative residues of CP and CB were incorporated to the soil together with farmyard manure (FYM), prior to establishing the tomato crop. The FB plants were incorporated to the soil at anthesis together with either FYM or composted olive-mill waste (CO). Green manuring with FB resulted in higher soil mineral N levels during the subsequent tomato crop and higher tomato fruit yield when combined with FYM, compared to compost. The level of soil mineral N was the main restrictive factor for yield in organic greenhouse tomato. FB for green manuring as preceding crop to tomato increased significantly the level of soil mineral N and tomato yield compared to CB or CP aiming to produce green pods. The lowest tomato yield was obtained when the preceding crop was CB cultivated for green pod production. The soil mineral N was significantly higher when FYM was applied as base dressing compared with CO, despite the higher total N concentration in CO, pointing to slower mineralization rates of CO during tomato cultivation.

Legume-Based Mobile Green Manure Can Increase Soil Nitrogen Availability and Yield of Organic Greenhouse Tomatoes.

Information about the availability of soil mineral nitrogen (N) in organic greenhouse tomatoes after the application of mobile green manure (MGM), and its impact on plant nutrient status and yield is scarce. Considering this knowledge gap, the effects of legume biomass from faba beans that are cultivated outdoors (FAB), or from feed-grade alfalfa pellets at two different doses (AAL = 330 g m-2; AAH = 660 g m-2) that were applied as MGM on the nutrition and yield of an organic greenhouse crop of tomatoes were evaluated. All of the MGM treatments increased the mineral N concentrations in the soil throughout the cropping period, and the total N concentration in tomato leaves when compared to the untreated control. FAB and AAH treatments had a stronger impact than AAL in all of the measured parameters. In addition, AAL, AAH, and FAB treatments increased the yield compared to the control by 19%, 33%, and 36%, respectively. The application of MGM, either as faba bean fresh biomass or as alfalfa dry pellets, in organic greenhouse tomatoes significantly increased the plant available soil N, improved N nutrition, and enhanced the fruit yield. However, the N mineralization rates after the MGM application were excessive during the initial cropping stages, followed by a marked decrease thereafter. This may impose an N deficiency during the late cropping period.

Conversion from mineral fertilisation to MSW compost use: Nitrogen fertiliser value in continuous maize and test on crop rotation.

The recycling of agricultural wastes, co-products, and by-products is necessary for creating circular economic (closed loop) agro-food chains and more sustainable agro-ecosystems. The substitution of N mineral fertilisers with recycled organic fertiliser promotes a circular economy, makes the agricultural system more environmentally sustainable, and guarantees food security. Results from a continuous maize experiment and four-year rotation cropping systems (maize, winter wheat, maize, and soybean) were used in a three-year study that replaced part or all mineral fertilisers with Municipal Solid Waste Compost (MSWC). In the first experiment, two different fertilisation strategies, MSWC only (M-Com) and mineral fertilisers (M-Min), were compared with zero nutrients (M-Test 0), whereas in the rotation cropping systems, mineral fertilisation (R-Min) was compared with a combination of MSWC and mineral fertilisers (R-Com + Min). Depressed yields resulted in the initial year of compost application, but by the middle term (three years), MSWC fertilisation showed a good N fertiliser value, mainly for yield summer crops and integrated with N mineral fertilisers. Different soil indicators and the N content in crop tissues and soil suggested that the scarce N availability recorded mainly during the first year is responsible for yield reduction. Due to limited supplies of MSWC, soil total N and the stable organic fraction bound tightly to minerals (MOM), did not vary significantly in the three-year experiment. Conversely, the more labile organic fraction (fPOM) increased only in the top soil layers (0-15 cm). Also in the top layer, M-Com increased the amount of organic fraction occluded into soil aggregates (oPOM). Furthermore, replacement of N mineral fertiliser with compost effectively mitigated N2O emissions in wheat and maize. Overall, the fertiliser value of MSWC was maximised when it was used repeatedly and in combination with mineral fertiliser, especially in spring and summer crops.

Strigolactones Control Root System Architecture and Tip Anatomy in Solanum Lycopersicum L. Plants under P Starvation.

The hormones strigolactones accumulate in plant roots under phosphorus (P) shortage, inducing variations in plant phenotype. In this study, we aimed at understanding whether strigolactones control morphological and anatomical changes in tomato (Solanum lycopersicum L.) roots under varying P supply. Root traits were evaluated in wild-type seedlings grown in high vs low P, with or without exogenous strigolactones, and in wild-type and strigolactone-depleted plants grown first under high vs no P, and then under high vs no P after acclimation on low P. Exogenous strigolactones stimulated primary root and lateral root number under low P. Root growth was reduced in strigolactone-depleted plants maintained under continuous P deprivation. Total root and root hair length, lateral root number and root tip anatomy were impaired by low strigolactone biosynthesis in plants grown under low P or transferred from low to no P. Under adequate P conditions, root traits of strigolactone-depleted and wild-type plants were similar. Concluding, our results indicate that strigolactones i) control macro- and microscopic changes of root in tomato depending on P supply; and ii) do not affect root traits significantly when plants are supplemented with adequate P, but are needed for acclimation to no P and typical responses to low P.

Sustainable magnet-responsive nanomaterials for the removal of arsenic from contaminated water.

In this study, chitosan and bio-based substances (BBS) obtained from composted biowaste were used as stabilizers for the synthesis of magnet-sensitive nanoparticles (NPs) via coprecipitation method. A pyrolysis treatment was carried out on both biopolymers at 550°C, and their consequent conversion into a carbon matrix was followed by means of different physicochemical characterization techniques (mainly FTIR spectroscopy and XRD), whereas magnetic properties were evaluated by magnetization curves. The prepared materials were tested in water remediation processes from arsenic (As) species (both inorganic and organic forms). These tests, explained by means of the most common adsorption models, evidenced that the best performances were reached by both materials obtained after pyrolysis treatments, pointing out the promising application of such magnet-sensitive materials as easy-recoverable tools for water purification treatments.

Dung beetles as drivers of ecosystem multifunctionality: Are response and effect traits interwoven?

Rapid biodiversity loss has emphasized the need to understand how biodiversity affects the provisioning of ecological functions. Of particular interest are species and communities with versatile impacts on multiple parts of the environment, linking processes in the biosphere, lithosphere, and atmosphere to human interests in the anthroposphere (in this case, cattle farming). In this study, we examine the role of a specific group of insects - beetles feeding on cattle dung - on multiple ecological functions spanning these spheres (dung removal, soil nutrient content and greenhouse gas emissions). We ask whether the same traits which make species prone to extinction (i.e. response traits) may also affect their functional efficiency (as effect traits). To establish the link between response and effect traits, we first evaluated whether two traits (body mass and nesting strategy, the latter categorized as tunnelers or dwellers) affected the probability of a species being threatened. We then tested for a relationship between these traits and ecosystem functioning. Across Scandinavian dung beetle species, 75% of tunnelers and 30% of dwellers are classified as threatened. Hence, nesting strategy significantly affects the probability of a species being threatened, and constitutes a response trait. Effect traits varied with the ecological function investigated: density-specific dung removal was influenced by both nesting strategy and body mass, whereas methane emissions varied with body mass and nutrient recycling with nesting strategy. Our findings suggest that among Scandinavian dung beetles, nesting strategy is both a response and an effect trait, with tunnelers being more efficient in providing several ecological functions and also being more sensitive to extinction. Consequently, functionally important tunneler species have suffered disproportionate declines, and species not threatened today may be at risk of becoming so in the near future. This linkage between effect and response traits aggravates the consequences of ongoing biodiversity loss.

Paramagnetic iron-doped hydroxyapatite nanoparticles with improved metal sorption properties. A bioorganic substrates-mediated synthesis.

This paper describes the synthesis of paramegnetic iron-containing hydroxyapatite nanoparticles and their increased Cu(2+) sorbent capacity when using Ca(2+) complexes of soluble bioorganic substrates from urban wastes as synthesis precursors. A thorough characterization of the particles by TEM, XRD, FTIR spectroscopy, specific surface area, TGA, XPS, and DLS indicates that loss of crystallinity, a higher specific area, an increased surface oxygen content, and formation of surface iron phases strongly enhance Cu(2+) adsorption capacity of hydroxyapatite-based materials. However, the major effect of the surface and morphologycal modifications is the size diminution of the aggregates formed in aqueous solutions leading to an increased effective surface available for Cu(2+) adsorption. Maximum sorption values of 550-850 mg Cu(2+) per gram of particles suspended in an aqueous solution at pH 7 were determined, almost 10 times the maximum values observed for hydroxyapatite nanoparticles suspensions under the same conditions.