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991.
Mostafa M. Rady Mohamed A. Seif El-Yazal Hanan A. A. Taie Safia M. A. Ahmed 《Journal of Crop Science and Biotechnology》2016,19(5):363-371
Polyamines [i.e. spermine (Spm), spermidine (Spd) and putrescine (Put)] antagonistic effects on stress imposed by 2.0 mM lead (Pb2+) on growth, yield and its components and changes in the osmoprotectant and endogenous Pb2+ concentrations, the contents of some nutrients and tissue health in wheat plants were evaluated. Under the three applied polyamine (PAs) applications, the efficiency of wheat plants to tolerate Pb2+ stress in terms of growth and yield characteristics was noticed to varying degrees. The enhancements in osmoprotectant concentrations and plant health [in terms of relative water content (RWC) and membrane stability index (MSI)], and reductions in electrolyte leakage (EL) and plant Pb2+ concentration were correlated with the reasonable growth of Pb2+-stressed plants and their grain yield. Results point out that, better growth and yield characteristics, MSI, RWC, leaf photosynthetic pigment and osmoprotectant concentrations, and nutrient contents were obtained with seed soaking in 0.25 mM Spm, 0.50 mM Spd or 1.0 mM Put than those generated with seed soaking in water under 2.0 mM Pb2+ stress. In contrast, EL and the concentration of endogenous Pb2+ were significantly reduced. However, the Pb2+-free control positively exceeded the all stressed treatments. Among all tested PAs, 1.0 mM Put showed the best results and thus is recommended, as seed soaking, for wheat to grow well under Pb2+ stress. 相似文献
992.
993.
Context
Strategic placement of fuel treatments across large landscapes is an important step to mitigate the collective effects of fires interacting over broad spatial and temporal extents. On landscapes where highly invasive cheatgrass (Bromus tectorum) is increasing fire activity, such an approach could help maintain landscape resilience.Objectives
Our objectives are to 1) model and map fire connectivity on a cheatgrass-invaded landscape, as well as the centrality of large cheatgrass patches, in order to inform a landscape fuel treatment (i.e., a network of greenstrips); and 2) evaluate the modeled greenstrip network based on changes to cheatgrass patch centrality.Methods
Our analysis covers 485-km2 on the Kaibab National Forest in Northern Arizona. We apply a circuit-theoretic model of fire connectivity between all pairs of large cheatgrass patches. Based on these results, we calculate a measure of centrality for each patch to inform fuel treatment placement. We evaluate the modeled greenstrip network by comparing the pre- and post-treatment centrality of each patch.Results
After modeling fire connectivity across the landscape, we identify 25 of 68 large cheatgrass patches with relatively high centrality. When we simulate greenstrips around these focal patches, model results suggest that they are effective in reducing the centrality for at least 19 of the 25 patches.Conclusions
Fire connectivity models provide robust network centrality measures, which can help generate multiple, landscape fuel treatment alternatives and facilitate on-the-ground decisions. The extension of these methods is well suited for landscape fuels management in other vegetation communities and ecosystems.994.
Barbara Moser Christoph Bachofen Jonathan D. Müller Marek Metslaid Thomas Wohlgemuth 《Annals of Forest Science》2016,73(4):959-970
Key message
Pinus sylvestris seedlings quickly expand their roots to deeper soil layers while Pseudotsuga menziesii concentrates its root system in the topsoil, thereby running the risk of desiccation during long dry spells, as indicated by lower survival after simulated summer drought.Context
Pseudotsuga menziesii (Douglas-fir) is regarded as a promising species to maintain the productivity of Central European lowland forests given the projected increase of long dry spells.Aims
Will the species be able to regenerate from seed and spread outside plantations in a drier temperate Europe?Methods
We measured the relative growth rate, biomass allocation, root architecture, and phenotypic plasticity of Pseudotsuga menziesii seedlings sown in a common garden and grown under current precipitation and prolonged drought, respectively. The species’ competitive ability with respect to Pinus sylvestris L., the most drought-tolerant native conifer in Central Europe, was assessed during three growing seasons.Results
Pinus sylvestris seedlings had higher relative growth rates than did Pseudotsuga menziesii seedlings, first in terms of aboveground biomass and later in terms of shoot height. This resulted in heavier and taller seedlings after three growing seasons under both moist and dry conditions. Shorter vertical roots corresponded with lower survival of Pseudotsuga menziesii seedlings under dry conditions.Conclusion
Fast root proliferation allows Pinus sylvestris seedlings to reach deeper water pools that are less rapidly depleted during transient drought. By contrast, the shallow root system might put Pseudotsuga menziesii seedlings at the risk of desiccation during prolonged dry spells.995.
Antti Mäkinen Markus Holopainen Annika Kangas Jussi Rasinmäki 《European Journal of Forest Research》2010,129(5):887-897
Developments in the field of remote sensing have led to various cost-efficient forest inventory methods at different levels
of detail. Remote-sensing techniques such as airborne laser scanning (ALS) and digital photogrammetry are becoming feasible
alternatives for providing data for forest planning. Forest-planning systems are used to determine the future harvests and
silvicultural operations. Input data errors affect the forest growth projections and these effects are dependent on the magnitude
of the error. Our objective in this study was to determine how the errors typical to different inventory methods affect forest
growth projections at individual stand level during a planning period of 30 years. Another objective was to examine how the
errors in input data behave when different types of growth simulators are used. The inventory methods we compared in this
study were stand-wise field inventory and single-tree ALS. To study the differences between growth models, we compared two
forest simulators consisting of either distance-independent tree-level models or stand-level models. The data in this study
covered a 2,000-ha forest area in southern Finland, including 240 sample plots with individually measured trees. The analysis
was conducted with Monte Carlo simulations. The results show that the tree-level simulator is less sensitive to errors in
the input data and that by using single-tree ALS data, more precise growth projections can be obtained than using stand-wise
field inventory data. 相似文献
996.
Gerardo Ordaz-Ochoa Aureliano Juárez-Caratachea Rosa Elena Pérez-Sánchez Rafael María Román-Bravo Ruy Ortiz-Rodríguez 《Tropical animal health and production》2017,49(5):1025-1033
The effect of spineless cactus intake (Opuntia ficus-indica) on blood glucose (BG) levels in lactating sows and its impact on daily and total feed intake (dFI?1 and TFI, respectively), body weight loss (BWL), and weaning-estrus interval length (WEI) were evaluated. Thirty-four hybrid (Yorkshire × Landrace × Pietrain) sows in lactation phase were used. Sows were divided into two groups: G1 (n = 17) where they received commercial feed and G2 (n = 17) provided with commercial feed plus an average of 2.0 ± 0.5 kg spineless cactus, based on a sow’s body weight. The variables evaluated were BG, dFI?1, TFI, BWL, and WEI. Statistical analysis was performed by using a fixed and mixed model methodology, under a repeated measurements experiment. Group effects were found on all analyzed variables (P < 0.05). The BG was lower in G2 (55.2 and 64.5 mg/dL pre- and post-prandial, respectively), compared to that in G1 (70.9 and 80.1 mg/dL pre- and post-prandial, respectively) (P < 0.05). G2 showed better performance than G1 for dFI?1, BWL, and WEI (P < 0.05) whose averages were 5.5 ± 1.8 kg, 7.4 ± 4.5%, and 5.3 ± 1.2 days, respectively. Averages for these variables in G1 were 4.7 ± 1.5 kg, 16.8 ± 4.6%, and 6.1 ± 1.6 days, respectively. Intake of spineless cactus reduced BG levels in lactating sows, generating greater dFI?1, lower BWL at the end of lactation, and a lower WEI. 相似文献
997.
Yong-Xin Liu Gui-Xing Wang Yu-Fen Wang Fei Si Zhao-Hui Sun Xiao-Yan Zhang Jia-Di Wang Hai-Jin Liu 《Fisheries Science》2011,77(1):87-93
To estimate genetic parameters of growth traits in Japanese flounder Paralichthys olivaceus, full-sib and half-sib families were produced in three consecutive years at the Beidaihe Central Experiment Station in China.
Each year 8–28 families were produced. The body weight, body length and body depth at 180, 240, and 360 days of age were measured
for 5,224 individuals. Four animal models were used to examine the phenotypic variation of growth traits and were compared
using the likelihood ratio test. The results showed that estimates for additive genetic effect heritabilities varied greatly
depending on the model, trait and age. The maternal effect had a significant impact on phenotypic variation only for body
depth at 180 days of age, which explained 49% of the phenotypic variance. The ratio of full-sib effect to phenotypic variation
ranged from 0.09 to 0.22. Growth traits all exhibited low heritability (0.13–0.39), indicating that there is the potential
for family selection breeding for these traits in Japanese flounder. Using the full model with the fixed, full-sib family,
additive and maternal genetic effects, genetic correlations among the three traits for fish of the same age were estimated
to be more than 0.80. Generally, the genetic correlations gradually increased as age increased. 相似文献
998.
Iray Gell Antonieta De Cal Rosario Torres Josep Usall Paloma Melgarejo 《European journal of plant pathology / European Foundation for Plant Pathology》2008,121(4):487-498
Five field experiments were performed in commercial orchards located in Lleida (Spain) over three growing seasons, 2000–2002,
in order to estimate the relationship between the incidence of latent infection caused by Monilinia spp. in peaches and the incidence of post-harvest brown rot. No latent infection was recorded at popcorn and the maximum
incidence occurred pre-harvest; in some orchards a second peak was detected during the pit hardening period. Monilinia laxa is the most prevalent species isolated from peaches with brown rot. There was a positive correlation between the incidence
of latent infection and that of post-harvest brown rot. The average incidence of latent infection during the crop season explained
55% of the total variation in the incidence of post-harvest brown rot. The effect of temperature (T) and duration of wetness (W) on the incidence of latent infection in peach and nectarine orchards was analysed using multiple regression. The regression
analysis indicated that T and W jointly explained 83% of the total variation in the incidence of latent infection. The model predicts no latent infections
when T < 8°C, and >22 h wetness are required when T = 8°C but only 5 h at 25°C are necessary for latent infection to occur. The incidence of brown rot and latent infection of
peaches caused by M. laxa under controlled experimental conditions were also affected by T and W, as well as by fruit maturity and inoculum concentration. Latent infections were produced in fruit when T was not suitable for the development of brown rot symptoms. In these experiments more than 4–5 h of daily wetness were required
after embryo growth in fruit sprayed to run-off with an inoculum concentration higher than 104 conidia ml−1 of M. laxa for brown rot and latent infections to develop. The fitted model obtained from the field data was able to predict the observed
data obtained under controlled environmental conditions. 相似文献
999.
An integrated approach of remote sensing,GIS and swarm intelligence for zoning protected ecological areas 总被引:1,自引:0,他引:1
Interest in protecting ecological areas is increasing because of land uses conflicts and environmental pressures. The optimal
zoning of protected ecological areas belongs to a NP-hard problem because it is subject to both box and spatial constraints.
A challenge in solving area optimization problems emerges with the increasing size of a study region. In this article, an
integrated approach of remote sensing, GIS and modified ant colony optimization (ACO) is proposed for application in zoning
protected ecological areas. Significant modifications have been made in the conventional ACO so that it can be further extended
to solve zoning problems in large regions. An improved selection strategy is designed to accelerate the progress of sites
selection for artificial ants. Another important modification in ACO is to incorporate the neighborhood diffusion strategy
into pheromone updating. The optimal objective is to generate protected areas that maximize both ecological suitability and
spatial compactness. The modified ACO model has been successfully applied to a case study involving an area of 25,483 cells
in Dongguan, Guangdong, China. The experiments have demonstrated that the proposed model is an efficient and effective optimization
technique for generating optimal protection. The modified ACO model only requires approximately 119 s for determining near-optimal
solutions. Furthermore, the proposed method performs better than other methods, including simulated annealing, genetic algorithm,
iterative relaxation, basic ACO, and density slicing. 相似文献
1000.
The riverscape perspective recognizes the heterogeneous habitat types within the stream corridor as a single, integrated ecological
unit operating across spatial scales. Although there is ample evidence that the riverscape notion is appropriate in understanding
the physical phenomena of stream corridors, significantly less attention has focused on its ecological ramifications. To this
end, we surveyed riverscape habitat variables and bird community characteristics in the Champlain Valley of Vermont, USA.
From the data collected, we used information theoretic methodology (AICc) to model relationships between bird community attributes and key habitat variables across the riverscape. Our models with
the greatest support suggest that riverine bird communities respond to a suite of characteristics; representing a variety
of riverscape habitats at the in-stream, floodplain, and riparian levels. Channel slope, drainage area, percent conifers,
and in-stream habitat condition were among the most influential variables. We found that piscivores are potentially important
indicators of riverscape condition, responding to a host of variables across the riverscape. Our results endorse a holistic
approach to assessing and managing the mosaic of patches in the riverscape and suggest that a riverscape approach has significant
conservation potential. 相似文献