Dampened behavioral and physiological responses mediate birds’ association with humans     

Gerardo Jiménez  Jesús A. Lemus  Leandro Meléndez  Guillermo Blanco  Paola Laiolo 《Biological conservation》2011,(5):1702-1711

The study of the mechanisms involved in phenotypic adaptations or plasticity to environmental stressors may serve to evaluate contemporary ecological and evolutionary dynamics in threatened or growing wildlife populations. By addressing human disturbance as a main stressor agent, we investigated antipredator response (flushing distance), social behavior (degree of gregarism), health (fecal pathogens), and endocrine status (fecal corticosterone levels) as potential mechanisms that permit birds to cope with anthropogenic impact in tourist areas. Our study models were species that are neither urbanized nor invasive, and that are typical of the high mountains of the Palearctic: the Alpine and the Red-billed chough (Pyrrhocorax graculus and P. pyrrhocorax), and the surrounding alpine bird community. Both chough species showed habituation, reduced flushing distances, fewer parasites and lower corticosterone levels in tourist than in non-tourist sites, and a significant variation in gregarious behavior. Behavioral and physiological adjustments permitted these corvids to optimize resource exploitation depending on habitat quality and in conditions of continuous disturbance. Human-induced changes in chough social behavior had no effect on local avian species richness, a surrogate measure for community diversity. Irrespectively of chough aggregations, bird diversity decreased significantly in recreational areas, thus not all community members tolerated human impact as choughs did. Our findings suggest that species that manage to coexist with humans primarily adjust traits that influence ecological interactions (social, foraging or antipredatory responses) and that vary rapidly (learned behaviors and physiological mechanisms that promote homeostasis).  相似文献   

Silicon amendment improves wheat defence against Fusarium graminearum and complements the control by fungicide of Fusarium head blight     

Paulo Cesar Pazdiora  Rosane Lopes Crizel  Keilor da Rosa Dorneles  Sabrina Monks da Silva  Thomas Natali Morello  Fabio Clasen Chaves  Leandro José Dallagnol 《Plant pathology》2023,72(1):53-66

A three-year field experiment with two wheat cultivars evaluated the effect of soil-applied silicon (Si), with and without fungicide spraying, on Fusarium head blight (FHB) control. Silicon treatment alone reduced FHB severity and the percentage of damaged wheat kernels, regardless of the cultivar. The best disease control was obtained for the cultivar with moderate disease resistance (MR), supplied with silicon and treated with fungicide during flowering. Silicon treatment alone promoted an increase in deoxynivalenol (DON) concentration in the disease-susceptible cultivar; however, in the MR cultivar, silicon amendment associated with fungicide treatment led to a reduction in DON concentration. Greenhouse experiments evaluated the effect of silicon combined with different timings of fungicide application on wheat defences against Fusarium graminearum. Plants supplied with silicon had a longer pathogen incubation period, lower FHB severity and lower DON concentration when compared to plants without silicon. In addition, silicon-supplied plants had higher soluble phenolic content and altered antioxidant enzyme activities (SOD, CAT, POX and PPO) that favoured early accumulation of hydrogen peroxide when compared to plants without silicon. Greater control of FHB and lower DON concentration in plants treated with silicon and fungicide before inoculation and up to 1 day after inoculation was associated with increased levels of defence-associated metabolites. Silicon contributed to the reduction of FHB and DON concentration in wheat, especially for the MR cultivar and, when combined with fungicide spraying, both MR and disease-susceptible cultivars had enhanced performances upon silicon amendment.  相似文献   

Hydrosedimentology of nested subtropical watersheds with native and eucalyptus forests     

Miriam Fernanda Rodrigues  José Miguel Reichert  Jean Paolo Gomes Minella  Leandro Dalbianco  Rodrigo Luiz Ludwig  Rafael Ramon  Lilian Alessandra Rodrigues  Norton Borges Júnior 《Journal of Soils and Sediments》2014,14(7):1311-1324

Purpose

Information on the effects of eucalyptus forests on hydrosedimentological processes is scarce, particularly at the catchment scale. Monitoring and mathematical modeling are efficient scientific tools used to address the lack of information for natural resource management and the representation and prediction of those processes. This study evaluates the effects of eucalyptus cultivation on hydrosedimentological processes in watersheds and to use the Limburg soil erosion model (LISEM) to represent and predict hydrological processes.

Material and methods

The study was conducted in two forested watersheds: the main watershed (94.46 ha) and a nested sub-watershed (38.86 ha), both cultivated with eucalyptus and residual riparian native forest, located in southern Brazil. Hydrosedimentalogical monitoring was conducted from 16th February 2011 to 31st December 2012, and LISEM model calibrations were performed on the bases of six storms events.

Results and discussion

The sediment yield for 2011 was 41.6 Mg km^?2 and 38.5 Mg km^?2 for the watershed and sub-watershed, respectively. An extreme event in 2012 provided greater sediment yield for the sub-watershed (99.8 Mg km^?2) than that for the watershed (51.7 Mg km^?2). Rainfall events with a greater maximum intensity generated rapid discharge and suspended sediment concentration responses in the sub-watershed due to the smaller drainage area and steeper landscape. In the main watershed, the accumulation of flood waves occurred for most events, with less steep hydrographs, and a later occurrence of the discharge peak after that of the sub-watershed. The LISEM adequately reproduced the peak discharge and runoff for the calibrated events; however, the peak time and the shape of the hydrograph were not adequately represented.

Conclusions

The hydrosedimentological patterns of the watershed and sub-watershed, both cultivated with eucalyptus, was characterized by sedimentographs preceding hydrographs during rainfall–runoff events where scale effects occur, with maximum discharge and specific sediment yield greater in the watershed than that in the sub-watershed. Empirical models based on hydrologic variables may be used for estimating the suspended sediment concentration and sediment yield. Therefore, LISEM may be used for the prediction of hydrological variables in these forested watersheds.  相似文献   

Description of hydrological and erosion processes determined by applying the LISEM model in a rural catchment in southern Brazil     

Cláudia Alessandra Peixoto de Barros  Jean Paolo Gomes Minella  Leandro Dalbianco  Rafael Ramon 《Journal of Soils and Sediments》2014,14(7):1298-1310

Purpose

Hydrosedimentological modeling is a tool that can be used to understand better important processes occurring at the catchment scale, such as runoff and sediment yield. The aim of this study was to use the Limburg Soil Erosion Model (LISEM) to describe the runoff and sediment yield during rainfall–runoff events in a small rural catchment in southern Brazil.

Materials and methods

The study was conducted in the Lajeado Ferreira Creek catchment (drainage area of 1.19 km²) where intense land use has caused a negative impact on water resources. Thirteen rainfall–runoff events that occurred in 2010 and 2011, including high-magnitude events, were used to model hydrosedimentological processes.

Results and discussion

Results

from the calibration and validation stages indicate that the model had a good performance when representing the hydrograph, including events with greater complexity. The use of a second soil layer in the model increased its efficiency, which is in accordance with the importance of subsurface flow in this catchment and its sensitivity to the physical properties of the soil, which are essential for controlling hydrosedimentological processes at the catchment scale. The simulation of sediment yield was overestimated by the model, constrained by the lack of sensitivity of the model to soil cohesion and the stability of soil aggregates. During the model calibration stage, these parameters had values different from those measured in the field.

Conclusions

The LISEM model performed well in representing runoff for events of different magnitudes. The discretization of the physical–hydrologic properties in the soil profile enabled the evaluation of the effect of subsurface impediment layers on water infiltration and runoff. The simulation was less accurate for suspended sediment concentration than for runoff. This indicates the need for further studies to either identify other factors controlling erosion and sediment yield that have not been identified by the model, or identify if the representation of the physical parameters is inadequate, especially the values of soil cohesion and aggregate stability.  相似文献   

Searching for bioactive compounds from Solanaceae: lethal and sublethal toxicity to Spodoptera frugiperda and untargeted metabolomics approaches     

Lima  Andre&#;sa Fabri  do Prado Ribeiro  Leandro  Gon&#;alves  Gabriel Luiz Padoan  Maimone  Naydja Moralles  Gissi  Danilo Soares  de Lira  Simone Possedente  Vendramim  Jos&#; Djair 《Journal of pest science》2022,95(3):1317-1329

Journal of Pest Science - The fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a major pest of maize crops and others row crops on the American continent, and this...  相似文献   

NITRATE UPTAKE KINETICS AND METABOLIC PARAMETERS IN TWO RICE VARIETIES GROWN IN HIGH AND LOW NITRATE     

Leandro Azevedo Santos  Walterliny Almeida Santos  Marcus Vinícius Loss Sperandio  Carlos Alberto Bucher  Sonia Regina de Souza  Manlio Silvestre Fernandes 《Journal of plant nutrition》2013,36(7):988-1002

A study was conducted on the effect of nitrate (NO₃) levels on nitrate uptake kinetics and nitrogen (N) metabolism in two rice varieties, Piaui (landrace) and IAC-47 (improved). At 27 days after germination (DAG) N supply was suspended for 72 h, and then restored as 0.2 or 2 mM nitrate. The nitrate uptake kinetics was determined by the depletion method. Plants were harvested at 0, 6, and 24 h. Plants of the Piaui variety under 0.2 mM nitrate showed higher V_max and lower K_M, indicating higher efficiency of nitrate uptake at low supply. In the sheaths of both varieties, there was a greater accumulation of nitrate and lower activities of nitrate reductase and glutamine synthetase. The V-H⁺-ATPase activity increased between 0 and 6 h accompanying the nitrate influx, suggesting that the activity of this proton pump is necessary for the antiport activity (H⁺/2NO^? ₃) involved in the accumulation of nitrate into vacuoles.  相似文献   

Effects of Low Doses of Glufosinate-Ammonium on Upland Rice Agronomic Traits     

Ferrari  Samuel  Seródio Mettifogo  Odin  Luís Oliveira Cunha  Matheus  Fernando dos Santos Cordeiro  Luis  do Valle Polycarpo  Gustavo  Tropaldi  Leandro 《Gesunde Pflanzen》2021,73(3):297-306

The use of herbicides and growth regulators in agricultural crops to reduce vegetative growth is widely studied worldwide. This study aimed to evaluate the agronomic traits of upland rice subjected to low doses of glufosinate-ammonium applied at different development stages. The treatments consisted of five low doses (0; 15; 30; 60; and 100?g a.i. ha^?1; a.i.: active ingredient) of glufosinate-ammonium herbicide: a single low dose between active tillering (AT) and floral differentiation (FD); a single low dose after FD; low dose divided into two applications, the first at the beginning of the AT and the second between AT and FD; low dose divided into three applications, the first at the beginning of the AT, the second between AT and FD and the third after the FD, with four replications. The agronomic traits of upland rice were negatively affected due to the application of low doses of glufosinate-ammonium, with reduction in grain yield, 1000-grain weight, number of panicles, full spikelets and spikelets per panicle. Glufosinate-ammonium has no potential to be used as hormesis effect in rice plants due to loss in grain yield.

  相似文献   

Effects of Level and Degradability of Rapeseed Meal in Rations for Dairy Cows. 1. Animal Performance     

Jan Bertilsson  Horacio Leandro Gonda  Jan Erik Lindberg 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2013,63(4):222-229

Abstract

A total of 44 dairy cows of the Swedish Red and White dual-purpose breed were divided into 4 equal groups. Two groups were fed concentrate containing approximately 19% crude protein (high level), while two groups were fed concentrate containing 14.3% crude protein (low level). The differences were obtained by mixing either 25 or 8% 00-rapeseed meal into a basic grain-dominated mixture. Within each protein level, one half of the cows were allotted untreated rapeseed meal and the other half heat-treated rapeseed meal. The heat treatment decreased the effective protein degradability of the rapeseed meal by 20 units from 72 to 52%.

The experiment was commenced as a continuous experiment, where weeks 1–3 of the lactation were a preliminary period in which all cows received the same feeding. The experimental period covered lactation weeks 4–20. When the experiment was analysed, the results from the preliminary period were used as covariates.

Significant treatment effects were reached both for level and degradability. This was mainly due to a significantly lower milk and protein production on the treatment URM - low protein level. This treatment also reached a significantly lower feed energy utilization and a higher fat percentage in milk. It was concluded that evaluating the protein according to the new Nordic AAT/PBV system correlated better to milk production than did crude protein or digestible crude protein.

By using the AAT-PBV system it was possible to minimize the crude protein content in the concentrate without impairing milk production. A general conclusion is that there are benefits in the form of higher milk production and better feed utilization from decreasing protein degradability in rapeseed meal.  相似文献   

Increased CO2 emission and organic matter decomposition by leaf-cutting ant nests in a coastal environment     

Leandro Sousa-Souto  Danielle Caroline de Jesus Santos  Bianca Giuliano Ambrogi  Mário Jorge Campos dos Santos  Marcelo Braga Bueno Guerra  Edenir Rodrigues Pereira-Filho 《Soil biology & biochemistry》2012,44(1):21-25

Leaf-cutting ants perform a vital role in the cycling of carbon and nutrients in tropical ecosystems. Nests have high levels of organic matter and refuse dumps host up to two times more soil micro-organisms than non-nest soil. The increased levels of organic matter in the soil of nests, however, can affect CO₂ emissions from soil and alter the balance of atmospheric CO₂. We aimed at assessing the effect of nests of the leaf-cutting ant Acromyrmex balzani on CO₂ emissions in a coastal area of Northeast Brazil. Results show that A. balzani nests emitted up to four times more CO₂ than the surrounding soil and emissions were positively correlated with soil moisture and soil organic matter (SOM) content. In addition, field experiments demonstrated that refuse material has a lower residence time than the leaf material brought to the colonies. Despite the high density of nests and high content of SOM compared to adjacent control soil, CO₂ emissions by A. balzani nests represent only 0.3% of the total CO₂ efflux by the studied ecosystem. Although these effluxes account for a relative small portion of the total soil CO₂ emission, they are still important for the understanding of C balance, especially when one considers the thousands of tons of CO₂ emitted each day, across entire Neotropical regions where leaf-cutting ants occur.  相似文献   

Genetic variability for responses to short‐ and long‐term salt stress in vegetative sunflower plants     

Dolores Bustos  Leandro Ismael Ortega  Alicia Córdoba  Abelardo Vegetti  Edith Taleisnik 《植物养料与土壤学杂志》2012,175(6):882-890

Sunflower (Helianthus annuus L.) has been rated as moderately salt‐resistant, and variability for salt resistance has been detected within this crop. However, variability in salt‐resistance mechanisms has not been assessed. Osmotic tolerance, the relation of salt resistance with whole‐plant Na⁺ and K⁺ distribution and tissue Na⁺ tolerance were investigated in several sunflower inbred lines. Plants were grown under controlled conditions, in pots with sand and perlite irrigated with salinized (NaCl, –0.65 MPa) nutrient solution. Osmotic tolerance was assessed from the initial effects of the salt treatment on plant elongation in eleven sunflower lines. Long‐term salinity responses were evaluated in four of those lines, by assessing whole‐plant growth. A principal components analysis (PCA) was run on relative‐to‐control growth data, and this information was used to establish a relative resistance ranking, which indicated lines HAR2 > HAR1 > HA64 > HAR5. Osmotic tolerance was observed in HA64 and HAR2. The lines showed different degrees of Na⁺ accumulation, it was very low in some of them, but relative salt resistance was not associated to this trait. Tissue Na⁺ tolerance was deduced by comparing the percentage of dead leaves as a function of leaf blade Na⁺ accumulation, and it was higher in HAR1 than in the rest. These results indicate that variability for salt‐resistance mechanisms exists in sunflower. Osmotic tolerance and tissue Na⁺ tolerance were detected in different lines, highlighting that such variability may be exploited for increasing salt resistance in this crop.  相似文献