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The use of lignocellulosic residues, originating from sawdust, in composting sewage sludge for organic fertilizer production, is a practice of growing interest. However, few studies have explored the effect of the proportion of sawdust and sewage sludge raw materials on composting performance in the humification process. This study assessed the addition of sawdust in the sewage sludge composting process, regarding carbon content, presence of heavy metals, and humification of the organic compost. The experimental design employed was a randomized complete block design with five treatments featuring different proportions of organic residues to achieve C/N ratios between 30-1 (T1: 100% sewage sludge and 0% sawdust, T2: 86% sewage sludge and 14.0% sawdust, T3: 67% sewage sludge and 33% sawdust, T4: 55% sewage sludge and 45% sawdust, and T5: 46.5% sewage sludge and 53.5% sawdust) and five replications, totaling 25 experimental units. The addition of lignocellulosic residue in sewage sludge composting increased the levels of TOC and the C/N ratio, reduced the levels of pH, P, N, Na, Ba, and Cr, and did not interfere with the levels of K, Ca, Mg, S, CEC, labile carbon, and metals Fe, Zn, Cu, Mn, Ni, and Pb. The increase in the proportion of sawdust residue favored the degradation of aliphatic groups, increasing the presence of aromatic structures and reducing humification at the end of composting. The use of sawdust as a lignocellulosic residue in sewage sludge composting is a viable and efficient alternative to produce high-quality organomineral fertilizers.

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Dissolved organic matter (DOM) contributes to forest C cycling. We assessed temporal variability, sources, and transformations of DOM during four years in a tropical montane forest with the help of stable C isotope ratios (δ13C values). We measured δ13C values of DOM in rainfall (RF), throughfall (TF), stemflow (SF), litter leachate (LL), soil solutions at the 0.15 and 0.30 m depths (SS15, SS30), and streamflow (ST) with TOC-IRMS. The δ13C values of DOM did not vary seasonally. We detected an event with a high δ13C value likely attributable to black carbon from local pasture fires. The mean δ13C values of DOM outside the event decreased in the order, RF (-26.0 ± 1.3‰) > TF (-28.7 ± 0.3‰) > SF (-29.2 ± 0.2‰) > LL (-29.6 ± 0.2‰) because of increasing leaching of C-isotopically light compounds. The higher δ13C values of DOM in SS15 (-27.8 ± 1.0‰), SS30 (-27.6 ± 1.1‰), and ST (-27.9 ± 1.1‰) than in the above-ground solutions suggested that roots and root exudates are major belowground DOM sources. Although in DOM the C/N ratios correlated with the δ13C values when all solutions were considered, this was not the case for SS15, SS30, and ST alone. Thus, the δ13C values of DOM provide an additional tool to assess the sources and turnover of DOM.

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BACKGROUND: Net blotch (NB), caused by Pyrenophora teres f. teres (Ptt), is an important disease of barley worldwide. NB control is commonly achieved through the use of fungicide mixtures including strobilurins, triazoles and carboxamides. Succinate dehydrogenase inhibitors (SDHI) are important components of fungicide management programs of barley diseases. However, during the last growing seasons in Argentina, barley fields sprayed with mixtures containing SDHI fungicides have shown failures in NB control. Here, we report the isolation and characterization of Argentine Ptt strains resistant to SDHI fungicides. RESULTS: Compared against a sensitive (wild-type) reference strain collected in 2008, all 21 Ptt isolates collected in 2021 exhibited resistance to pydiflumetofen and fluxapyroxad both in vitro and in vivo. Concordantly, all of them presented target-site mutations in any of the sdhB, sdhC and sdhD genes. Although the mutations detected have been previously reported in other parts of the world, this study documents for the first time the occurrence of double mutations in the same Ptt isolate. Specifically, the double mutation sdhC-N75S + sdhD-D145G confers high resistance to SDHI fungicides, while the double mutations sdhB-H277Y + sdhC-N75S and sdhB-H277Y + sdhC-H134R confer moderate levels of resistance in Ptt. CONCLUSIONS: SDHI-resistance in Argentine Ptt populations is expected to increase. These findings emphasize the urgent need to perform a wider survey and a more frequent monitoring of SDHI sensitivity of Ptt populations and to develop and implement effective antiresistance tactics. © 2023 Society of Chemical Industry.

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BACKGROUND: C:N:P homeostasis in plants guarantees optimal levels of these nutrients in plant metabolism. H However, one of the causes to the effects of deficit irrigation is the loss of C:N:P homeostasis in leaves and stems that causes reduction in the growth of sugarcane. Being able to measure the impact of water deficit on C:N:P homeostasis in plants from the stoichiometric ratios of the concentrations of these nutrients in leaves and stems. This loss causes a decrease in nutritional efficiency, but can be mitigated with the use of silicon. Silicon favors the homeostasis of these nutrients and crop productivity. The magnitude of this benefit depends on the absorption of Si by the plant and Si availability in the soil, which varies with the type of soil used. Thus, this study aims to evaluate whether the application of Si via fertigation is efficient in increasing the absorption of Si and whether it is capable of modifying the homeostatic balance of C:N:P of the plant, causing an increase in nutritional efficiency and consequently in the production of biomass in leaves and stems of sugarcane ratoon cultivated with deficient and adequate irrigations in different tropical soils. RESULTS: Water deficit caused biological losses in concentrations and accumulation of C, N, and P, and reduced the nutrient use efficiency and biomass production of sugarcane plants cultivated in three tropical soils due to disturbances in the stoichiometric homeostasis of C:N:P. The application of Si increased the concentration and accumulation of Si, C, N, and P and their use efficiency and reduced the biological damage caused by water deficit due to the modification of homeostatic balance of C:N:P by ensuring sustainability of the production of sugarcane biomass in tropical soils. However, the intensity of attenuation of such deleterious effects stood out in plants cultivated in Eutrophic Red Oxisols. Si contributed biologically by improving the performance of sugarcane ratoon with an adequate irrigation due to the optimization of stoichiometric ratios of C:N:P; increased the accumulation and the use efficiency of C, N, and P, and promoted production gains in biomass of sugarcane in three tropical soils. CONCLUSION: Our study shows that fertigation with Si can mitigate the deleterious effects of deficient irrigation or potentiate the beneficial effects using an adequate irrigation system due to the induction of a new stoichiometric homeostasis of C:N:P, which in turn improves the nutritional efficiency of sugarcane cultivated in tropical soils.

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Biofloc technology is much highlighted these days because of its tremendous effects on aquaculture. Microbes were enriched on cheapest organic carbon source i. e., powdered banana peels and were incorporated in different aquaria rearing grass carp fingerlings under different C/N treatments (10:1, 15:1 and 20:1) and 10% water daily water exchange. The initial growth of fingerlings was recorded. The experiment was settled in triplicates for 60 days and run parallel to control group provided with commercial feed and daily water exchange. Its effect was evaluated by measuring the growth of fingerlings and water parameters of each aquarium. The average % gain in weight and length of fingerlings was obtained significantly highest (28.12 ± 0.30g and 17.29 ± 0.46cm respectively) in aquaria containing pure powdered banana peels with 10% water exchange and C/N ratio was adjusted at 20: 1 (T3) than other treatments and control. Ammonia and other water parameters were also under control in T3 than other experimental and control groups. By all counts, it was concluded that the highest C/N ratio in biofloc system had the potential to increment C. idella growth rate by reducing toxicity and could be used as fish meal substitute.(AU)

A tecnologia Biofloc é muito destacada hoje em dia por causa de seus tremendos efeitos na aquicultura. Os micróbios foram enriquecidos com a fonte de carbono orgânico mais barata, i. e., cascas de banana em pó, e foram incorporadas em diferentes aquários de criação de alevinos de carpa-capim sob diferentes tratamentos C/N (10: 1, 15: 1 e 20: 1) e 10% de troca diária de água. O crescimento inicial dos alevinos foi registrado. O experimento foi resolvido em triplicatas por 60 dias e executado paralelamente ao grupo controle fornecido com ração comercial e troca diária de água. Seu efeito foi avaliado medindo o crescimento dos alevinos e os parâmetros da água de cada aquário. O% de ganho médio em peso e comprimento dos alevinos foi obtido significativamente mais alto (28,12 ± 0,30g e 17,29 ± 0,46 cm respectivamente) em aquários contendo cascas de banana em pó puro com 10% de troca de água e a relação C/N foi ajustada em 20: 1 (T3) do que outros tratamentos e controle. A amônia e outros parâmetros da água também estavam sob controle no T3 mais do que nos outros grupos experimentais e de controle. Por todas as contagens, concluiu-se que a maior razão C/N no sistema de bioflocos tem o potencial de incrementar a taxa de crescimento de C. idella reduzindo a toxicidade e pode ser usada como substituto da farinha de peixe.(AU)

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Biofloc technology is much highlighted these days because of its tremendous effects on aquaculture. Microbes were enriched on cheapest organic carbon source i. e., powdered banana peels and were incorporated in different aquaria rearing grass carp fingerlings under different C/N treatments (10:1, 15:1 and 20:1) and 10% water daily water exchange. The initial growth of fingerlings was recorded. The experiment was settled in triplicates for 60 days and run parallel to control group provided with commercial feed and daily water exchange. Its effect was evaluated by measuring the growth of fingerlings and water parameters of each aquarium. The average % gain in weight and length of fingerlings was obtained significantly highest (28.12 ± 0.30g and 17.29 ± 0.46cm respectively) in aquaria containing pure powdered banana peels with 10% water exchange and C/N ratio was adjusted at 20: 1 (T3) than other treatments and control. Ammonia and other water parameters were also under control in T3 than other experimental and control groups. By all counts, it was concluded that the highest C/N ratio in biofloc system had the potential to increment C. idella growth rate by reducing toxicity and could be used as fish meal substitute.

A tecnologia Biofloc é muito destacada hoje em dia por causa de seus tremendos efeitos na aquicultura. Os micróbios foram enriquecidos com a fonte de carbono orgânico mais barata, i. e., cascas de banana em pó, e foram incorporadas em diferentes aquários de criação de alevinos de carpa-capim sob diferentes tratamentos C/N (10: 1, 15: 1 e 20: 1) e 10% de troca diária de água. O crescimento inicial dos alevinos foi registrado. O experimento foi resolvido em triplicatas por 60 dias e executado paralelamente ao grupo controle fornecido com ração comercial e troca diária de água. Seu efeito foi avaliado medindo o crescimento dos alevinos e os parâmetros da água de cada aquário. O% de ganho médio em peso e comprimento dos alevinos foi obtido significativamente mais alto (28,12 ± 0,30g e 17,29 ± 0,46 cm respectivamente) em aquários contendo cascas de banana em pó puro com 10% de troca de água e a relação C/N foi ajustada em 20: 1 (T3) do que outros tratamentos e controle. A amônia e outros parâmetros da água também estavam sob controle no T3 mais do que nos outros grupos experimentais e de controle. Por todas as contagens, concluiu-se que a maior razão C/N no sistema de bioflocos tem o potencial de incrementar a taxa de crescimento de C. idella reduzindo a toxicidade e pode ser usada como substituto da farinha de peixe.

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Abstract Biofloc technology is much highlighted these days because of its tremendous effects on aquaculture. Microbes were enriched on cheapest organic carbon source i. e., powdered banana peels and were incorporated in different aquaria rearing grass carp fingerlings under different C/N treatments (10:1, 15:1 and 20:1) and 10% water daily water exchange. The initial growth of fingerlings was recorded. The experiment was settled in triplicates for 60 days and run parallel to control group provided with commercial feed and daily water exchange. Its effect was evaluated by measuring the growth of fingerlings and water parameters of each aquarium. The average % gain in weight and length of fingerlings was obtained significantly highest (28.12 ± 0.30g and 17.29 ± 0.46cm respectively) in aquaria containing pure powdered banana peels with 10% water exchange and C/N ratio was adjusted at 20: 1 (T3) than other treatments and control. Ammonia and other water parameters were also under control in T3 than other experimental and control groups. By all counts, it was concluded that the highest C/N ratio in biofloc system had the potential to increment C. idella growth rate by reducing toxicity and could be used as fish meal substitute.

Resumo A tecnologia Biofloc é muito destacada hoje em dia por causa de seus tremendos efeitos na aquicultura. Os micróbios foram enriquecidos com a fonte de carbono orgânico mais barata, i. e., cascas de banana em pó, e foram incorporadas em diferentes aquários de criação de alevinos de carpa-capim sob diferentes tratamentos C/N (10: 1, 15: 1 e 20: 1) e 10% de troca diária de água. O crescimento inicial dos alevinos foi registrado. O experimento foi resolvido em triplicatas por 60 dias e executado paralelamente ao grupo controle fornecido com ração comercial e troca diária de água. Seu efeito foi avaliado medindo o crescimento dos alevinos e os parâmetros da água de cada aquário. O% de ganho médio em peso e comprimento dos alevinos foi obtido significativamente mais alto (28,12 ± 0,30g e 17,29 ± 0,46 cm respectivamente) em aquários contendo cascas de banana em pó puro com 10% de troca de água e a relação C/N foi ajustada em 20: 1 (T3) do que outros tratamentos e controle. A amônia e outros parâmetros da água também estavam sob controle no T3 mais do que nos outros grupos experimentais e de controle. Por todas as contagens, concluiu-se que a maior razão C/N no sistema de bioflocos tem o potencial de incrementar a taxa de crescimento de C. idella reduzindo a toxicidade e pode ser usada como substituto da farinha de peixe.

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Stable isotope (SI) analysis is a standard tool to study marine food webs, usually based on the measurement of a few individuals from a small list of subjectively pre-defined species. The main objective of this study was to find out which species are significantly associated with the temporal variability of the SI composition of zooplankton in a tropical marine ecosystem. We investigated this by means of a novel species-biomass-isotopes-mixture (SBIM) approach that uses a relative biomass matrix to explain the SI signature of the zooplankton community. Furthermore, SBIM was applied to detect key taxa that can be considered bioindicators for important descriptors of ecosystem state (e.g., oligotrophy, carbon sources, mean trophic level). Plankton samples (64 µm mesh size) were obtained in Tamandaré Bay (northeastern Brazil) from June 2013 to August 2019. One aliquot of each sample was taken for stable isotope measurements and one for taxonomic identification and estimation of size and relative biomass. Total zooplankton biomass differed significantly between years, seasons and stations. Total zooplankton δ13C values ranged from -21.0 to -18.2‰ (mean ± standard deviation: -19.7 ± 0.7‰ in the dry season, and -19.4 ± 0.8‰ in the rainy season). Total zooplankton δ15N values ranged from 3.8 to 9.0‰ (7.0 ± 1.0‰ in the dry season, and 6.5 ± 1.2‰ rainy season). Total zooplankton C/N ratios ranged from 3.5 to 5.0 (4.2 ± 0.4 in the dry season and 4.2 ± 0.3 in the rainy season). The sparsely abundant and relatively large-sized copepod Pseudodiaptomus acutus was the most important species for explaining the variability in δ15N (22% of the total variability). Relative biomass (%) of P. acutus showed a strong positive correlation with δ15N, indicating a high trophic level (TL). Our results highlight the importance of less abundant taxa for marine food webs. Small-sized invertebrate larvae were negatively correlated with δ15N, indicating a TL below average. The copepod Dioithona oculata was the most important organism in explaining the δ13C of zooplankton (17.7% of the total variability, positive correlation with δ13C), indicating possible selective use of a13C-enriched food source (e.g., diatoms) by this cyclopoid copepod. Oithona spp. juveniles showed a negative relationship with zooplankton C/N ratio, which can be indicators of an oligotrophic ecosystem state and lipid-poor zooplankton. The tintinnid F. ehrenbergii showed a positive correlation with C/N, being an indicator for turbid "green waters'', during the rainy season, when the ecosystem was in a eutrophic state, with high lipid contents in the zooplankton community. The proposed SBIM approach opens up a novel pathway to understanding the factors and species that shape the temporal variability of food webs.

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The impact of the organic carbon to nitrate ratio (C/N ratio) on mixotrophic denitrification rate has been scarcely studied. Thus, this work aims to investigate the effect of the C/N ratio on the mixotrophic denitrification when methanol is used as a source of organic matter and elemental sulfur as an electron donor for autotrophic denitrification. For this, two initial concentrations of NO3--N (50 and 25 mg/L) at a stoichiometric ratio of S0/N, and four initial C/N ratios (0, 0.6, 1.2, and 1.9 mg CH3OH/mg NO3- -N) were used at 25 (±2) °C. The results showed that when using a C/N ratio of 0.6, the highest total nitrogen removal was obtained and the accumulation of nitrites was reduced, compared to an autotrophic system. The most significant contribution to nitrate consumption was through autotrophic denitrification (AuDeN) for a C/N ratio of 0.6 and 1.2, while for C/N = 1.9 the most significant contribution of nitrate consumption was through heterotrophic denitrification (HD). Finally, organic supplementation (methanol) served to increase the specific nitrate removal rate at high and low initial concentrations of substrate. Therefore, the best C/N ratio was 0.6 since it allowed for increasing the removal efficiency and the denitrification rate.

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Montane cloud forests are fragile biodiversity hotspots. To attain their conservation, disentangling diversity patterns at all levels of ecosystem organization is mandatory. Biotic communities are regularly structured by environmental factors even at small spatial scales. However, studies at this scale have received less attention with respect to larger macroscale explorations, hampering the robust view of ecosystem functioning. In this sense, fungal small-scale processes remain poorly understood in montane cloud forests, despite their relevance. Herein, we analyzed soil fungal diversity and ecological patterns at the small-scale (within a 10 m triangular transect) in a pristine montane cloud forest of Mexico, using ITS rRNA gene amplicon Illumina sequencing and biogeochemical profiling. We detected a taxonomically and functionally diverse fungal community, dominated by few taxa and a large majority of rare species (81%). Undefined saprotrophs represented the most abundant trophic guild. Moreover, soil biogeochemical data showed an environmentally heterogeneous setting with patchy clustering, where enzymatic activities suggest distinctive small-scale soil patterns. Our results revealed that in this system, deterministic processes largely drive the assemblage of fungal communities at the small-scale, through multifactorial environmental filtering.

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Microplastics (MPs) are distributed in a wide range of aquatic and terrestrial ecosystems throughout the planet. They are known to adsorb hazardous substances and can transfer them across the trophic web. To eliminate MPs pollution in an environmentally friendly process, we propose using a photocatalytic process that can easily be implemented in wastewater treatment plants (WWTPs). As photocatalysis involves the formation of reactive species such as holes (h+), electrons (e-), hydroxyl (OH●), and superoxide ion (O2●-) radicals, it is imperative to determine the role of those species in the degradation process to design an effective photocatalytic system. However, for MPs, this information is limited in the literature. Therefore, we present such reactive species' role in the degradation of high-density polyethylene (HDPE) MPs using C,N-TiO2. Tert-butanol, isopropyl alcohol (IPA), Tiron, and Cu(NO3)2 were confirmed as adequate OH●, h+, O2●- and e- scavengers. These results revealed for the first time that the formation of free OH● through the pathways involving the photogenerated e- plays an essential role in the MPs' degradation. Furthermore, the degradation behaviors observed when h+ and O2●- were removed from the reaction system suggest that these species can also perform the initiating step of degradation.

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The waste generated in the production of wine and grape juice is characterized by a high concentration of organic matter, when properly treated, can serve as sustainable strategies for its use and destination, and among these, the production of biocompost. Thus, the objective of this study was to evaluate the process of composting grape marc, sheep manure, and mango leaves, evaluating in the biocompost its physical-chemical, nutritional and microbiological characteristics for use in agriculture. The composting pile assembly followed the proportion of 30% of sheep manure as nitrogenous material and 70% of carbon-rich material (divided into 50% of grape marc and 20% of hose leaves), the initial C/N ratio was 33:1, and the process lasted 120 days according to legislation. When evaluating the results, the process occurred in an accelerated manner, where at 30 days the biocompost was already stabilized, and at the end of the process (120 days) it presented a C/N ratio of 5.85, as well as acceptable levels for the macronutrients K and P, and without risk of phytotoxicity, and could be used as organic fertilizer or as soil conditioner, reducing environmentally inadequate destination and generating savings with their reinsertion in the production chain.

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Composting is an environment-friendly method for recycling organic waste, and incorporation of heat and aeration can enhance favorable conditions for microbial growth in the process. This research aimed to evaluate the influence of the introduction of solar heat and aeration to the waste grass exposed to the composting process. The compost piles studied were subjected to different processes: application of solar-heated aeration, only-aeration, solar heating with a greenhouse, and control. Solar-heated air was introduced to a compost pile of grass clippings and compared with a greenhouse compost system. The composting process of 70 days was monitored for temperature, oxygen, moisture, organic matter loss, and humification rate. Germination index has been used to evaluate the maturation of the composts produced. The highest temperature was obtained at the compost pile with the greenhouse. This system reached the highest temperature (68.2 °C) on day 15; the ambient temperature on that day was 20.6 °C. The decreases in the C/N ratios after day 70 of composting were 20% and 15% for the greenhouse and the system where solar-heated air was introduced, respectively. Although the temperature of the solar-heated air was higher than that of the greenhouse, thermophilic temperature levels could not be reached in the aerated compost pile, which indicated a cooling effect of excessive aeration even with the heated air. Composting of grass clippings resulted in a decrease in organic matter content and enhancement in seed germination and root growth, obtaining high GI levels, inferring no phytotoxicity. This study showed that composting of grass clippings with low C/N ratios and high humidity can still be possible by using solar energy.

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Phasins are amphiphilic proteins involved in the regulation of the number and size of polyhydroxybutyrate (PHB) granules. The plant growth promoting bacterium Azospirillum brasilense Sp7 accumulates high quantities of bioplastic PHB as carbon and energy source. By analyzing the genome, we identified six genes that code for proteins with a Phasin_2 domain. To understand the role of A. brasilense Sp7 PhaP1 (PhaP1Abs) on PHB synthesis, the phaP1 gene (AMK58_RS17065) was deleted. The morphology of the PHB granules was analyzed by transmission electron microscopy (TEM) and the PHB produced was quantified under three different C:N ratios in cultures subjected to null or low-oxygen transfer. The results showed that PhaP1Abs is involved in PHB granules morphology and in controlling early biopolymer accumulation. Using RT-PCR it was found that phasin genes, except phaP4, are transcribed in accordance with the C:N ratio used for the growth of A. brasilense. phaP1, phaP2 and phaP3 genes were able to respond to the growth conditions tested. This study reports the first analysis of a phasin protein in A. brasilense Sp7.

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In addition to plant-derived, fungal pigments have become an alternative in respect to synthetic ones. Besides Monascus sp., several pigment-producing fungi do not have culture conditions well-established yet. In this research, media composition, light wavelength and co-culture were evaluated, results were reported in Absorbance Units per gram of biomass (AU/Bgr). For Fusarium oxysporum a C:N ratio above 7 was advantageous, using both complex and defined media; blue LED light increased the AU/Bgr value from 18013 to 344; co-culture did not enhance pigment production. In Aspergillus chevalieri a high C:N ratio with glucose as carbon source was ideal. When exposing cultures to light, UV and red light gave the highest pigmentation; moreover, differential UV-VIS spectra in all wavelengths suggested production of additional pigments. Particularly a pigment observed when cultured in green light was also found in co-culture with yeast and there was an improvement of AU/Bgr value of 52549%. This is the first report regarding light effect and co-culture for these fungi, as well as C:N ratio for A. chevalieri.

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Through field and laboratory experiments we investigated the effects of leaf traits of two tree species and microbial conditioning on the abundance, biomass, and feeding preference of a typical macroinvertebrate shredder. In the field, we compared the association of Phylloicus (Calamoceratidae, Trichoptera) with two tree species commonly found in riparian zones, which are representative of high and low nutritional quality, respectively: Nectandra megapotamica and Chusquea tenella. In the laboratory, we investigated the feeding preference of Phylloicus using unconditioned leaves and leaves conditioned by aquatic fungi. The same tree species used in the field experiment were used in the laboratory. Initially, C. tenella leaves were proved to be more nutritious and softer, while N. megapotamica leaves were harder and more lignified. The shredders preferred conditioned leaf detritus of reduced toughness (field: C. tenella; laboratory: N. megapotamica, both conditioned for 14 days). These leaf traits seem to be crucial for the choice process of Phylloicus. After 14 days, N. megapotamica leaves showed a decreased toughness associated with the microbial conditioning, which explained its consumption rate by Phylloicus. In both field and laboratory experiments, we found evidence that Phylloicus is a selective feeding shredder, and that the leaf traits, especially leaf structure (e.g., leaf toughness and lignin content), determine its association and preferences.

Nós investigamos em experimento de campo e de laboratório os efeitos das características foliares e condicionamento microbiano de duas espécies de árvores na abundância, biomassa e preferência alimentar de um fragmentador típico. No experimento de campo, comparamos a associação do Phylloicus (Calamoceratidae, Trichoptera) entre duas espécies vegetais, comumente encontradas em zonas ripárias, que são representativas de alta e baixa qualidade nutricional, respectivamente: Nectandra megapotamica e Chusquea tenella. Em experimento de laboratório, investigamos a preferência alimentar de Phylloicus, usando folhas condicionadas e não condicionadas pelos fungos aquáticos. As mesmas espécies vegetais usadas no experimento de campo foram usadas em laboratório. Inicialmente, as folhas de C. tenella mostraram-se mais nutritivas e macias, enquanto que as de N. megapotamica foram mais duras e lignificadas. Os fragmentadores preferiram o detrito com menor dureza e condicionados pelos fungos (campo: C. tenella; laboratório: N. megapotamica, ambas condicionadas por 14 dias), ou seja, estes parecem ser os fatores determinantes para a escolha dos Phylloicus. Após 14 dias, as folhas de N. megapotamica apresentaram decréscimo na dureza, que está associado ao condicionamento microbiano, e que explicou o padrão de consumo por Phylloicus. Nós encontramos evidências em campo e em laboratório que os Phylloicus são seletivos em relação ao alimento e que as características foliares, especialmente relacionadas à estrutura da folha (ex. dureza foliar e lignina), determinam a associação e a preferência destes fragmentadores.

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ABSTRACT Through field and laboratory experiments we investigated the effects of leaf traits of two tree species and microbial conditioning on the abundance, biomass, and feeding preference of a typical macroinvertebrate shredder. In the field, we compared the association of Phylloicus (Calamoceratidae, Trichoptera) with two tree species commonly found in riparian zones, which are representative of high and low nutritional quality, respectively: Nectandra megapotamica and Chusquea tenella. In the laboratory, we investigated the feeding preference of Phylloicus using unconditioned leaves and leaves conditioned by aquatic fungi. The same tree species used in the field experiment were used in the laboratory. Initially, C. tenella leaves were proved to be more nutritious and softer, while N. megapotamica leaves were harder and more lignified. The shredders preferred conditioned leaf detritus of reduced toughness (field: C. tenella; laboratory: N. megapotamica, both conditioned for 14 days). These leaf traits seem to be crucial for the choice process of Phylloicus. After 14 days, N. megapotamica leaves showed a decreased toughness associated with the microbial conditioning, which explained its consumption rate by Phylloicus. In both field and laboratory experiments, we found evidence that Phylloicus is a selective feeding shredder, and that the leaf traits, especially leaf structure (e.g., leaf toughness and lignin content), determine its association and preferences.

RESUMO Nós investigamos em experimento de campo e de laboratório os efeitos das características foliares e condicionamento microbiano de duas espécies de árvores na abundância, biomassa e preferência alimentar de um fragmentador típico. No experimento de campo, comparamos a associação do Phylloicus (Calamoceratidae, Trichoptera) entre duas espécies vegetais, comumente encontradas em zonas ripárias, que são representativas de alta e baixa qualidade nutricional, respectivamente: Nectandra megapotamica e Chusquea tenella. Em experimento de laboratório, investigamos a preferência alimentar de Phylloicus, usando folhas condicionadas e não condicionadas pelos fungos aquáticos. As mesmas espécies vegetais usadas no experimento de campo foram usadas em laboratório. Inicialmente, as folhas de C. tenella mostraram-se mais nutritivas e macias, enquanto que as de N. megapotamica foram mais duras e lignificadas. Os fragmentadores preferiram o detrito com menor dureza e condicionados pelos fungos (campo: C. tenella; laboratório: N. megapotamica, ambas condicionadas por 14 dias), ou seja, estes parecem ser os fatores determinantes para a escolha dos Phylloicus. Após 14 dias, as folhas de N. megapotamica apresentaram decréscimo na dureza, que está associado ao condicionamento microbiano, e que explicou o padrão de consumo por Phylloicus. Nós encontramos evidências em campo e em laboratório que os Phylloicus são seletivos em relação ao alimento e que as características foliares, especialmente relacionadas à estrutura da folha (ex. dureza foliar e lignina), determinam a associação e a preferência destes fragmentadores.

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Through field and laboratory experiments we investigated the effects of leaf traits of two tree species and microbial conditioning on the abundance, biomass, and feeding preference of a typical macroinvertebrate shredder. In the field, we compared the association of Phylloicus (Calamoceratidae, Trichoptera) with two tree species commonly found in riparian zones, which are representative of high and low nutritional quality, respectively: Nectandra megapotamica and Chusquea tenella. In the laboratory, we investigated the feeding preference of Phylloicus using unconditioned leaves and leaves conditioned by aquatic fungi. The same tree species used in the field experiment were used in the laboratory. Initially, C. tenella leaves were proved to be more nutritious and softer, while N. megapotamica leaves were harder and more lignified. The shredders preferred conditioned leaf detritus of reduced toughness (field: C. tenella; laboratory: N. megapotamica, both conditioned for 14 days). These leaf traits seem to be crucial for the choice process of Phylloicus. After 14 days, N. megapotamica leaves showed a decreased toughness associated with the microbial conditioning, which explained its consumption rate by Phylloicus. In both field and laboratory experiments, we found evidence that Phylloicus is a selective feeding shredder, and that the leaf traits, especially leaf structure (e.g., leaf toughness and lignin content), determine its association and preferences.(AU)

Nós investigamos em experimento de campo e de laboratório os efeitos das características foliares e condicionamento microbiano de duas espécies de árvores na abundância, biomassa e preferência alimentar de um fragmentador típico. No experimento de campo, comparamos a associação do Phylloicus (Calamoceratidae, Trichoptera) entre duas espécies vegetais, comumente encontradas em zonas ripárias, que são representativas de alta e baixa qualidade nutricional, respectivamente: Nectandra megapotamica e Chusquea tenella. Em experimento de laboratório, investigamos a preferência alimentar de Phylloicus, usando folhas condicionadas e não condicionadas pelos fungos aquáticos. As mesmas espécies vegetais usadas no experimento de campo foram usadas em laboratório. Inicialmente, as folhas de C. tenella mostraram-se mais nutritivas e macias, enquanto que as de N. megapotamica foram mais duras e lignificadas. Os fragmentadores preferiram o detrito com menor dureza e condicionados pelos fungos (campo: C. tenella; laboratório: N. megapotamica, ambas condicionadas por 14 dias), ou seja, estes parecem ser os fatores determinantes para a escolha dos Phylloicus. Após 14 dias, as folhas de N. megapotamica apresentaram decréscimo na dureza, que está associado ao condicionamento microbiano, e que explicou o padrão de consumo por Phylloicus. Nós encontramos evidências em campo e em laboratório que os Phylloicus são seletivos em relação ao alimento e que as características foliares, especialmente relacionadas à estrutura da folha (ex. dureza foliar e lignina), determinam a associação e a preferência destes fragmentadores.(AU)

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RESUMO

Objetivou-se com este trabalho avaliar o efeito de sistemas de produção em semeadura direta com aporte diferenciado de palha e nitrogênio antecedendo ao cultivo da soja, visando aumento na produtividade desta leguminosa. O experimento foi instalado e conduzido em área experimental da Faculdade de Ciências Agrárias da Universidade do Oeste Paulista - UNOESTE, em Presidente Prudente/SP, em um solo classificado como Argissolo Vermelho distroférrico entre janeiro de 2014 e abril de 2016. O delineamento experimental adotado foi em blocos casualizados, com quatro repetições, em esquema de parcelas subdivididas, com quatro repetições, sendo as parcelas constituídas por três rotações de culturas, I) Milho/Tremoço/Soja, II) Milho+Urochloa brizantha/Soja, III) Urochloa brizantha/Soja, e as subparcelas por quatro doses de N (50, 100, 150 e 200 kg ha-1), aplicadas anualmente. Foram analisadas a quantidade de palha e sua persistência sobre o solo antes e após a semeadura da soja e a produtividade de soja nos dois anos do experimento. Os resultados foram submetidos à análise de variância e os efeitos das variáveis foram comparados pelo teste t ao nível de 5% de probabilidade. Os sistemas de produção influenciaram na quantidade de MS acumulada antes e após à semeadura da soja, nos dois anos avaliados. A relação C/N foi influenciada pela interação M+U na dose de 200 kg ha-1 de N antes da semeadura da soja. A quantidade de matéria seca produzida pela interação entre a Urochloa com 200 kg ha-1 de N, no momento da colheita da soja, evidenciaram que as rotações que utilizaram forrageiras produziram mais palha, e que a maior dose de N favoreceu positivamente a produtividade da forrageira e o maior aporte de C ao sistema. A adubação nitrogenada distribuída ao longo do ano agrícola tem potencial para aumentar a produtividade da soja, em anos sem restrição severa de água.

The aim of this study was to evaluate the effect of no-tillage systems with different input of straw and nitrogen before soybean crop to increase soybean yield. A field experiment was carried out in an experimental area of the University of Western São Paulo, College of Agricultural Sciences, in Presidente Prudente/SP, in a dystroferric red-yellow Argisol, between January 2014 and April 2016. A randomized complete block design was followed with four replications in a split plot where the plots consisted of (I) Maize/Lupine/Soybean, II) Maize + Urochloa brizantha/Soybean, III) Urochloa brizantha/Soybean and in the subplots four nitrogen doses (50, 100, 150 and 200 kg ha-1), applied annually. The amount of straw and its persistence on the soil before and after sowing of soybean and soybean yield in the two years of the experiment were analyzed. The results were submitted to analysis of variance and the effects of the variables were compared by Tukey test at the 5% probability level. The no-tillage systems influenced the amount of dry matter accumulated before and after soybean planting in the two evaluated years. The C/N ratio was influenced by interaction between M+U and 200 kg ha-1 of N before soybean seeding. The amount of dry matter obtained by the interaction of Urochloa with 200 kg ha-1 of N at the time of grain harvest, showed that the rotations that used forage produced more straw and that the supply of the highest nitrogen fertilizer dose favored the productivity of the forage and the greater contribution of C to the system. Nitrogen fertilization distributed throughout the agricultural year has the potential to increase soybean yield in years without severe water restriction.

Assuntos

RESUMO

Objetivou-se com este trabalho avaliar o efeito de sistemas de produção em semeadura direta com aporte diferenciado de palha e nitrogênio antecedendo ao cultivo da soja, visando aumento na produtividade desta leguminosa. O experimento foi instalado e conduzido em área experimental da Faculdade de Ciências Agrárias da Universidade do Oeste Paulista - UNOESTE, em Presidente Prudente/SP, em um solo classificado como Argissolo Vermelho distroférrico entre janeiro de 2014 e abril de 2016. O delineamento experimental adotado foi em blocos casualizados, com quatro repetições, em esquema de parcelas subdivididas, com quatro repetições, sendo as parcelas constituídas por três rotações de culturas, I) Milho/Tremoço/Soja, II) Milho+Urochloa brizantha/Soja, III) Urochloa brizantha/Soja, e as subparcelas por quatro doses de N (50, 100, 150 e 200 kg ha-1), aplicadas anualmente. Foram analisadas a quantidade de palha e sua persistência sobre o solo antes e após a semeadura da soja e a produtividade de soja nos dois anos do experimento. Os resultados foram submetidos à análise de variância e os efeitos das variáveis foram comparados pelo teste t ao nível de 5% de probabilidade. Os sistemas de produção influenciaram na quantidade de MS acumulada antes e após à semeadura da soja, nos dois anos avaliados. A relação C/N foi influenciada pela interação M+U na dose de 200 kg ha-1 de N antes da semeadura da soja. A quantidade de matéria seca produzida pela interação entre a Urochloa com 200 kg ha-1 de N, no momento da colheita da soja, evidenciaram que as rotações que utilizaram forrageiras produziram mais palha, e que a maior dose de N favoreceu positivamente a produtividade da forrageira e o maior aporte de C ao sistema. A adubação nitrogenada distribuída ao longo do ano agrícola tem potencial para aumentar a produtividade da soja, em anos sem restrição severa de água.(AU)

The aim of this study was to evaluate the effect of no-tillage systems with different input of straw and nitrogen before soybean crop to increase soybean yield. A field experiment was carried out in an experimental area of the University of Western São Paulo, College of Agricultural Sciences, in Presidente Prudente/SP, in a dystroferric red-yellow Argisol, between January 2014 and April 2016. A randomized complete block design was followed with four replications in a split plot where the plots consisted of (I) Maize/Lupine/Soybean, II) Maize + Urochloa brizantha/Soybean, III) Urochloa brizantha/Soybean and in the subplots four nitrogen doses (50, 100, 150 and 200 kg ha-1), applied annually. The amount of straw and its persistence on the soil before and after sowing of soybean and soybean yield in the two years of the experiment were analyzed. The results were submitted to analysis of variance and the effects of the variables were compared by Tukey test at the 5% probability level. The no-tillage systems influenced the amount of dry matter accumulated before and after soybean planting in the two evaluated years. The C/N ratio was influenced by interaction between M+U and 200 kg ha-1 of N before soybean seeding. The amount of dry matter obtained by the interaction of Urochloa with 200 kg ha-1 of N at the time of grain harvest, showed that the rotations that used forage produced more straw and that the supply of the highest nitrogen fertilizer dose favored the productivity of the forage and the greater contribution of C to the system. Nitrogen fertilization distributed throughout the agricultural year has the potential to increase soybean yield in years without severe water restriction.(AU)

Assuntos