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G. D. Berone F. A. Lattanzi M. G. Agnusdei N. Bertolotti 《Grass and Forage Science》2008,63(4):504-512
The aims of the experiment were to (i) test whether the higher leaf elongation rate per tiller (LERT) of Bromus stamineus D. than Lolium perenne L. at moderately low temperatures was maintained at high defoliation frequencies and (ii) explore responses in tiller dynamics during the onset of the cool season in the south‐east of the humid Pampas region in Argentina. The following treatments were applied: defoliation frequency at the 3·0‐leaf stage (i.e. one‐leaf lifespan), which is considered optimal, and higher defoliation frequency at the 1·5‐leaf stage (i.e. half‐of‐a‐leaf lifespan). The higher defoliation frequency reduced leaf elongation rate in both the species but it did not affect the leaf appearance rate. This confirms previous studies on several C3 grasses, suggesting a similar pattern of response. Changes in tiller size are proposed as a possible mechanism to explain such long‐term defoliation effects on leaf elongation rates. Responses in tiller production depended on the species considered. The higher defoliation frequency caused a reduction in site‐filling which led to lower tiller production rates in L. perenne but not in B. stamineus. Thus, B. stamineus maintained the advantage in LERT over L. perenne and its tiller production was not affected when defoliated at frequencies higher than those considered optimal. 相似文献
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Epron D Bahn M Derrien D Lattanzi FA Pumpanen J Gessler A Högberg P Maillard P Dannoura M Gérant D Buchmann N 《Tree physiology》2012,32(6):776-798
Pulse-labelling of trees with stable or radioactive carbon (C) isotopes offers the unique opportunity to trace the fate of labelled CO(2) into the tree and its release to the soil and the atmosphere. Thus, pulse-labelling enables the quantification of C partitioning in forests and the assessment of the role of partitioning in tree growth, resource acquisition and C sequestration. However, this is associated with challenges as regards the choice of a tracer, the methods of tracing labelled C in tree and soil compartments and the quantitative analysis of C dynamics. Based on data from 47 studies, the rate of transfer differs between broadleaved and coniferous species and decreases as temperature and soil water content decrease. Labelled C is rapidly transferred belowground-within a few days or less-and this transfer is slowed down by drought. Half-lives of labelled C in phloem sap (transfer pool) and in mature leaves (source organs) are short, while those of sink organs (growing tissues, seasonal storage) are longer. (13)C measurements in respiratory efflux at high temporal resolution provide the best estimate of the mean residence times of C in respiratory substrate pools, and the best basis for compartmental modelling. Seasonal C dynamics and allocation patterns indicate that sink strength variations are important drivers for C fluxes. We propose a conceptual model for temperate and boreal trees, which considers the use of recently assimilated C versus stored C. We recommend best practices for designing and analysing pulse-labelling experiments, and identify several topics which we consider of prime importance for future research on C allocation in trees: (i) whole-tree C source-sink relations, (ii) C allocation to secondary metabolism, (iii) responses to environmental change, (iv) effects of seasonality versus phenology in and across biomes, and (v) carbon-nitrogen interactions. Substantial progress is expected from emerging technologies, but the largest challenge remains to carry out in situ whole-tree labelling experiments on mature trees to improve our understanding of the environmental and physiological controls on C allocation. 相似文献
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Fiorella Cazzuli Carolina Bremm Martín Jaurena Dennis Poppi Martín Durante Marcelo Adolfo Benvenutti Jean Victor Savian Thais Devincenzi Pablo Rovira Ximena Lagomarsino Andrés Hirigoyen Fernando A. Lattanzi 《Grass and Forage Science》2023,78(2):306-316
It is unclear to what extent and on which variables does supplementing beef cattle on native grasslands affect sward structure, specifically on the dynamics of its grazing horizons. Three hypotheses were tested: (i) during a grazing down process under similar forage allowance, supplemented animals take longer to finish each grazing stratum, than their unsupplemented counterparts, (ii) in both cases, the upper stratum will be heavily depleted before the subsequent strata are grazed, (iii) some species and/or forage fractions are consumed faster than others, regardless of the animals being supplemented (corn dried distillers grains with solubles, DDGS, at 0.7% of their body weight, BW, on a dry matter, DM, basis) or not. Three blocks of stockpiled native grasslands were used and split into two treatments plots (n = 6), on which either supplemented (S) or control (C) heifers of 10.6 ± 0.6 months of age and an initial BW of 143 ± 9 kg, were used. A 2.5 × 0.5 m observation grid was installed on the sward, generating 384 observation points on each plot. On these observation plots, sward height (SH) and visually assessed green forage mass percentage (%G) were registered every other day for 12 consecutive days. No differences were found between the horizontal grazing dynamics between supplemented and control animals in terms of how they switched from the upper grazing horizon to the successive ones. In both cases, when the upper grazing horizon was heavily depleted, the subsequent horizon was being depleted by its half. Differences of preference for C3 species over C4 was observed for both treatments, but this effect was more meaningful for control animals. Grazing time never fully compensated for the decline in intake rate during depletion throughout the grazing horizons. Pasture intake declined when the animals transition from grazing the top grazing horizons to the lower horizons, irrespective of the level of supplementation. Managing the sward structure in terms of sward height will be beneficial to maximizing individual animal performance, for both C and S animals. Native grasslands paddocks with a greater C3 gasses predominance will always be preferred to C4 dominated paddocks, regardless of an eventual supplementation practice. 相似文献
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Fornasaro Silvia Morelli Guia Rimondi Valentina Fagotti Cesare Friani Rossella Lattanzi Pierfranco Costagliola Pilario 《Journal of Soils and Sediments》2022,22(2):656-671
Journal of Soils and Sediments - The extensive Hg contamination in soil and sediments occurring along the Paglia River (Central Italy) is the result of the interplay between the geomorphological... 相似文献
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Spatial analysis of genetic diversity in a comprehensive collection of the native grass Bromus auleticus Trinius (ex Nees) in Uruguay 
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下载免费PDF全文 Bromus auleticus Trinius (ex Nees) is a perennial allogamous C3 grass native to the Campos grasslands. It has potential to play a key role in restoration of both abandoned agricultural and overgrazed lands. We aim to reveal the existence of local adaptation and to assess whether phenotypes could be differentiated in relation to their ecogeographic region of origin. Previous reports estimated significant levels of variability among and within populations, but as yet there is no evidence of local adaptation and phenotypic relations with ecogeographic regions for this species. Indeed, there is a lack of knowledge about the spatial distribution of diversity, which limits the possibilities of using B. auleticus in ecological restoration and plant breeding. A comprehensive collection of 82 accessions of B. auleticus from eight ecogeographic regions within Uruguay was used to characterize diversity by measuring phenologic, morphologic, productive and reproductive traits. We found high diversity among B. auleticus accessions, and the spatial distribution of this diversity follows a pattern accounted by ecogeographic regions to a large extent. Our results also indicate large genotype × environment interaction, confirming local adaptation. Phenotypic values permitted, with a 3.7% error rate, discrimination of accessions according to their ecogeographic region of origin, suggesting the existence of differentiated ecotypes. We consider that the diversity observed should be conserved and used for breeding cultivars of this species and for the restoration of degraded grasslands by considering ecogeographic regions when selecting seed sources. 相似文献
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Persistence of tall fescue in a subtropical environment: tiller survival over summer in response to flowering control and nitrogen supply 下载免费PDF全文
下载免费PDF全文 J. M. Jáuregui D. F. Michelini M. G. Agnusdei J. Baudracco G. H. Sevilla P. Chilibroste F. A. Lattanzi 《Grass and Forage Science》2017,72(3):454-466
Enhancing pasture persistence is crucial to achieve more sustainable grass‐based animal production systems. Although it is known that persistence of perennial ryegrass is based on a high turnover of tillers during late spring and summer, little is known about other forage species, particularly in subtropical climates. To address this question, this study evaluated survival of grazed tall fescue tillers growing in a subtropical climate. We hypothesized that hard tactical grazing during winter to remove reproductive stems (designated as ‘flowering control’), and nitrogen fertilization in spring, would both improve tiller survival over summer, and thus enhance tiller density. This was assessed in two experiments. In both experiments, few tillers appeared during late spring and summer and so tiller density depended on the dynamics of vegetative tillers present in the sward in spring. In Experiment 2, flowering control and nitrogen fertilization both enhanced the survival of that critical tiller cohort, but the effects were not additive. Responses were similar but not statistically significant in Experiment 1, which had a warmer, drier summer and lower overall survival rates. Unlike grasses in temperate environments, persistence of tall fescue in this subtropical site appeared to follow a ‘vegetative pathway’; i.e., new tillers were produced largely in autumn, from vegetative tillers that survived the summer. 相似文献
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Almo Farina Emanuele Lattanzi Rachele Malavasi Nadia Pieretti Luigi Piccioli 《Landscape Ecology》2011,26(9):1257-1267
The soundscape is proposed as a phenomenological entity with which to investigate environmental complexity. In particular, the avian soundtope, which is defined as a place in which sound is intentionally structured by different bird species, is regarded as an agency acting to achieve several goals. In fact, the soundtope could be viewed as a special case of an eco-field used by birds, not only to establish territorial ownership and patrol an area but also as a means of locating and evaluating the availability of many other material and immaterial resources. The meaning of the multifaceted acoustic pattern produced by bird communities during the breeding season is discussed here under the acoustic niche hypothesis in terms of community coalescence and the permanent establishment of an inter-specific communication network. Furthermore, the spatial and temporal dimensions of a bird soundscape have also been analyzed and discussed in terms of their relationship with environmental proxies. A new Acoustic Complexity Index (ACI), coupled with the implementation (ACI plug-in) of a specific sound editor (WaveSurfer©), is proposed as a way of processing sound data efficiently, thus providing new opportunities to use the bird soundscape signature for landscape characterization and describing the ecological dynamics of long-term monitoring schemes. 相似文献
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