Sensitive Traits Research Articles

Probiotic potential and function of a Lactobacillus strain L1 isolated from Silage

AbstractOne strain L1 was isolated from silage and identified as Lactobacillus rhamnosus confirmed by sequencing of its 16S rDNA genes. The isolate in this study showed sensitive traits to antibiotics, including the clinically relevant antibiotic tetracycline. It showed inhibition against pathogen E. Coli, good adhesion ability to epithelial intestinal cell line LS‐174T and the strong competitive exclusion of E. coli adhesion to LS‐174T (84.1% exclusion). The gastrointestinal transit proved the strain survived well using a simulation of conditions. What's more, L1 induced slight cytokines to provoke an inflammatory response, but not lead to cell damage. Due to its capabilities to protect the host, L1 is good candidate for further studying potential benefits that support its use as probiotic, then the in vivo immunodulatory effects were investigated. The effect of the long‐term administration of skim milk containing L1 on the immune response in mice was analyzed. Values for CD3+, CD4+, and CD8+ cell populations were increased in relation to the control. The results obtained in this study suggest that the L. rhamnosus strain L1 has potential for use as probiotic and is likely to be immune‐enhancing for human use.Practical applicationLactobacillus belong to lactic acid bacteria that occur frequently in large numbers in various foods including vegetable, meat, and dairy products. Several properties may be evaluated to prove the potential of the bacteria before using them as probiotics. In this study, one of the Lactobacillus strains L1 isolated from the mixed grass and corn stalk silage exhibited above‐average results in all criteria observed in vitro including antibiotic susceptibility, antimicrobial activity, tolerance to gastrointestinal conditions, adhesion to intestinal cells, competitive exclusion of E. coli adhesion to epithelial cells, stimulation of immunity and benefit in animal experiment. The findings of our study suggest that L1 isolated from the silage may be potential probiotic for human use.

Historical Environment Is Reflected in Modern Population Genetics and Biogeography of an Island Endemic Lizard (Xantusia riversiana reticulata).

The restricted distribution and isolation of island endemics often produces unique genetic and phenotypic diversity of conservation interest to management agencies. However, these isolated species, especially those with sensitive life history traits, are at high risk for the adverse effects of genetic drift and habitat degradation by non-native wildlife. Here, we study the population genetic diversity, structure, and stability of a classic “island giant” (Xantusia riversiana, the Island Night Lizard) on San Clemente Island, California following the removal of feral goats. Using DNA microsatellites, we found that this population is reasonably genetically robust despite historical grazing, with similar effective population sizes and genetic diversity metrics across all sampling locations irrespective of habitat type and degree of degradation. However, we also found strong site-specific patterns of genetic variation and low genetic diversity compared to mainland congeners, warranting continued special management as an island endemic. We identify both high and low elevation areas that remain valuable repositories of genetic diversity and provide a case study for other low-dispersal coastal organisms in the face of future climate change.

Long-term effects of mowing on plasticity and allometry of Leymus chinensis in a temperate semi-arid grassland, China

Mowing is an important land management practice for natural semi-arid regions. A growing body of empirical evidence shows that different mowing regimes affect the functioning of grassland ecosystems. However, the responses of plant functional traits to long-term mowing and their allometric scaling under long-term mowing are poorly understood. For a better understanding of the effects of mowing on grassland ecosystems, we analyzed the allometric traits of leaves and stems of Leymus chinensis (Trin.) Tzvel., a dominant grass species in eastern Eurasian temperate grassland, at different mowing intensities (no clipping, clipping once every two years, once a year and twice a year). Experiments were conducted on plots established over a decade ago in a typical steppe of Xilinhot, Inner Mongolia, China. Results showed that most of the functional traits of L. chinensis decreased with the increased mowing intensity. The responses of leaves and stems to long-term mowing were asymmetric, in which leaf traits were more stable than stem traits. Also significant allometric relationships were found among most of the plant functional traits under the four mowing treatments. Sensitive traits of L. chinensis (e.g. leaf length and stem length) were primary indicators associated with aboveground biomass decline under high mowing intensity. In conclusion, the allometric growth of different functional traits of L. chinensis varies with different long-term mowing practices, which is likely to be a strategy used by the plant to adapt to the mowing disturbances.

Are rash impulsive and reward sensitive traits distinguishable? A test in young adults

Adolescents and young adults are characterized as prone to risky behavior with a wide range of traits identified as predictors of individual differences in this behavior. Here we test a crucial difference between traits that reflect rash impulsivity, the tendency to engage in risky behavior without consideration of consequences, versus reward sensitivity, the tendency to be attracted to novel and rewarding experience. To test the validity of this distinction, we examined the factorial structure of eight risk-related traits in a sample of 899 18 to 22year-olds. We predicted that rash impulsive traits would be separable in structure from reward sensitive traits and would uniquely predict relatively maladaptive risk-taking (e.g., drug use). In addition, we predicted that reward sensitive traits would be related to both adaptive (e.g., entering competitions) and maladaptive risk behaviors. Results revealed a factorial structure that distinguished these traits, with rash impulsive and reward sensitive traits uniquely predictive of different forms of risk-taking. The results suggest that it is possible to distinguish traits that reflect these two forms of risk-taking with implications for the measurement and interpretation of risk propensities in youth.

Genetic assimilation: a review of its potential proximate causes and evolutionary consequences.

Most, if not all, organisms possess the ability to alter their phenotype in direct response to changes in their environment, a phenomenon known as phenotypic plasticity. Selection can break this environmental sensitivity, however, and cause a formerly environmentally induced trait to evolve to become fixed through a process called genetic assimilation. Essentially, genetic assimilation can be viewed as the evolution of environmental robustness in what was formerly an environmentally sensitive trait. Because genetic assimilation has long been suggested to play a key role in the origins of phenotypic novelty and possibly even new species, identifying and characterizing the proximate mechanisms that underlie genetic assimilation may advance our basic understanding of how novel traits and species evolve. This review begins by discussing how the evolution of phenotypic plasticity, followed by genetic assimilation, might promote the origins of new traits and possibly fuel speciation and adaptive radiation. The evidence implicating genetic assimilation in evolutionary innovation and diversification is then briefly considered. Next, the potential causes of phenotypic plasticity generally and genetic assimilation specifically are examined at the genetic, molecular and physiological levels and approaches that can improve our understanding of these mechanisms are described. The review concludes by outlining major challenges for future work. Identifying and characterizing the proximate mechanisms involved in phenotypic plasticity and genetic assimilation promises to help advance our basic understanding of evolutionary innovation and diversification.

The Fat/Hippo signaling pathway links within-disc morphogen patterning to whole-animal signals during phenotypically plastic growth in insects.

Insects exhibit a diversity of environmentally sensitive phenotypes that allow them to be an extraordinarily successful group. For example, mandible size in male stag beetles is exquisitely sensitive to the larval nutritional environment and is a reliable signal of male condition. To date, studies of how such phenotypically plastic traits develop have focused on two types of mechanistic processes. Local, tissue-specific genetic mechanisms specify the shape and approximate final size of structures, whereas whole-animal hormonal signaling mechanisms modulate trait growth in response to environmental circumstance, including the body size and nutritional state of each individual. Hormones such as juvenile hormone, ecdysteroids, and/or ligands of the insulin-signaling pathway specify whether traits grow and regulate how much growth occurs across a diversity of insect groups. What remains to be shown is how the local, tissue-specific developmental genetic pathways interact with these whole animal hormonal signaling pathways during development to yield phenotypically plastic patterns of trait growth. Because the Fat/Hippo signaling pathway coordinates trait growth and development through its interactions with morphogens and hormonal pathways, we propose that Fat/Hippo signaling is a missing mechanistic link coordinating environmentally sensitive trait development in insects. Developmental Dynamics 244:1039-1045, 2015. © 2015 Wiley Periodicals, Inc.

Drought resistance of wheat alien chromosome addition lines evaluated by membership function value based on multiple traits and drought resistance index of grain yield

Drought is the single greatest abiotic stress leading to yield loss of wheat worldwide. The long-term domestication and selective breeding in artificial environments may have reduced the drought resistance of wheat. Wheat alien chromosome addition lines, with chromosomes derived from wild species, may possess drought resistant genetic potential and could serve as a bridge for transferring those traits to wheat. The drought resistance of 82 wheat alien chromosome addition lines along with their common parent Chinese Spring were evaluated for 10 agronomic traits under both well-watered and water-stressed conditions. Spike length was the most stable trait while biomass plant−1 was the most sensitive trait when subjected to drought stress. Evaluation of heritability and correlations with yield plant−1 suggested that plant height, peduncle length, distance between spike and flag leaf, grain number spike−1 and thousand-grain weight could be used as indicators of drought resistance. The membership function value of drought resistance (MFVD) based on those traits and grain yield plant−1, indicated 26 of the 82 wheat addition lines expressed high drought resistance. Higher MFVD was observed in the Agropyron elongatum 3E addition line in two years, and it was considered as the most drought resistant material. Analysis of the yield plant−1 suggested that the drought resistant addition lines identified by MFVD were drought resistant but not very high-yielding, thus they could be used to improve germplasm with high-yield potential but low drought resistance. The drought resistance index (DI) based on yield plant−1 indicated that 10 addition lines included both drought resistance and greater grain yield, which could be used in moderate stressed areas for improving drought resistance. Among them, addition lines with Aegilops peregrina 4SV and Ae. peregrina 3UV chromosome showed excellent performance and could be further investigated in drought resistance studies or breeding programs.

Contextual modulation of social and endocrine correlates of fitness: insights from the life history of a sex changing fish.

Steroid hormones are critical regulators of reproductive life history, and the steroid sensitive traits (morphology, behavior, physiology) associated with particular life history stages can have substantial fitness consequences for an organism. Hormones, behavior and fitness are reciprocally associated and can be used in an integrative fashion to understand how the environment impacts organismal function. To address the fitness component, we highlight the importance of using reliable proxies of reproductive success when studying proximate regulation of reproductive phenotypes. To understand the mechanisms by which the endocrine system regulates phenotype, we discuss the use of particular endocrine proxies and the need for appropriate functional interpretation of each. Lastly, in any experimental paradigm, the responses of animals vary based on the subtle differences in environmental and social context and this must also be considered. We explore these different levels of analyses by focusing on the fascinating life history transitions exhibited by the bi-directionally hermaphroditic fish, Lythrypnus dalli. Sex changing fish are excellent models for providing a deeper understanding of the fitness consequences associated with behavioral and endocrine variation. We close by proposing that local regulation of steroids is one potential mechanism that allows for the expression of novel phenotypes that can be characteristic of specific life history stages. A comparative species approach will facilitate progress in understanding the diversity of mechanisms underlying the contextual regulation of phenotypes and their associated fitness correlates.

Determinants of anti-predator tactics in hatchling grass snakes (Natrix natrix)

Many organisms exhibit diverse anti-predator tactics, influenced by genetics and prior experience. In ectothermic taxa, offspring phenotypes are often sensitive to developmental temperatures. If the effectiveness of alternative anti-predator responses depends on thermally sensitive traits, then the temperatures experienced during embryonic life should also affect how offspring respond to an approaching predator. We incubated 16 clutches of Swedish grass snakes (Natrix natrix) at a range of developmental temperatures, and scored body size, colour pattern, locomotor performance and anti-predator responses of 213 hatchlings from those clutches. A hatchling snake’s size and locomotor abilities were affected by its clutch of origin, its developmental temperature, and by an interaction between these two factors. Anti-predator tactics were strongly linked to locomotor ability, such that slower snakes tended to rely upon aggressive displays rather than flight. Incubation temperatures that generated slow (and thus aggressive) snakes also modified the colour of the snake’s nuchal spot. Temperatures in the low to medium range generated mostly cream, white and orange spots, whereas medium to high temperatures generated more yellow spots. Incubation effects, and gene X environment interactions, thus may generate complex correlations between morphology, locomotor ability, and anti-predator tactics.

Probiotic Properties of Enterococcus Strains Isolated from the Silage

AbstractThis study aimed to identify and evaluate the probiotic properties of five Enterococcus strains isolated from the silage using in vitro screening assays. Their metabolites, antibiotic susceptibility, antimicrobial activity, as well as their survival in the gastrointestinal tract (GIT) and adhesive ability to human intestinal cells were investigated. Among eight selected antibiotics, all the isolates showed sensitive traits to six particular antibiotics including tetracycline and vancomycin. L2–L5 showed inhibition zones against Escherichia coli and Salmonella except that L6 only inhibited the growth of E. coli. The GIT proved that all the strains were able to survive in low pH and bile salt conditions and they all can adhere to LS‐174T intestinal cells. L2 and L5 were then chosen to examine their competition activity toward E. coli and inflammatory response. The results showed that both strains exhibited strong competition activities toward E. coli. The displacement ratios were 98.4 and 97.7%, respectively. Compared with E. coli, L2 showed lower stimulation of interleukin (IL)‐8 and IL‐1β, while L5 induced higher levels of cytokines to provoke an inflammatory response. Finally, the in vivo effect of L2 was investigated. The data showed that L2 was harmless. The results obtained suggest that L2 is potentially probiotic.Practical ApplicationEnterococci are lactic acid bacteria that occur frequently in large numbers in various foods including vegetable, meat and dairy products. However, some of these bacteria are also recognized as nosocomial pathogens. Several properties may be evaluated to prove the potential of the bacteria before using them as probiotics. Results of this study indicated that five Enterococcus strains isolated from the mixed grass and corn stalk silage exhibited different capacties of antibiotic susceptibility, antimicrobial activity, tolerance to gastrointestinal conditions, adhesion to intestinal cells, and competitive exclusion of E. coli adhesion to epithelial cells and stimulation of immunity. Among these strains, L2 shows above‐average results in all probiotic criteria observed in vitro. Additionally, L2 was evaluated to be safe in mice feeding. The findings of our study suggest that L2 isolated from the silage may be potentially used as probiotic in humans.

Respondent privacy and estimation efficiency in randomized response surveys for discrete-valued sensitive variables

In some socio-economic surveys, data are collected on sensitive issues such as tax evasion, criminal conviction, drug use, etc. In such surveys, direct questioning of respondents is not of much use and the randomized response technique is used instead. A few researchers have studied the issue of privacy protection for surveys where the objective is to estimate the proportion of persons bearing the sensitive trait. Not much is known about respondent protection when the variable under study is a discrete quantitative variable and the objective is to estimate the population mean. In this article we study this issue. We propose a scheme for this issue and a measure of privacy. We show that given a stipulated level of this privacy measure, we can determine the parameter of the randomization device so as to maximize the efficiency of estimation, while guaranteeing the desired level of privacy protection.

Does land-use intensification decrease plant phylogenetic diversity in local grasslands?

Phylogenetic diversity (PD) has been successfully used as a complement to classical measures of biological diversity such as species richness or functional diversity. By considering the phylogenetic history of species, PD broadly summarizes the trait space within a community. This covers amongst others complex physiological or biochemical traits that are often not considered in estimates of functional diversity, but may be important for the understanding of community assembly and the relationship between diversity and ecosystem functions. In this study we analyzed the relationship between PD of plant communities and land-use intensification in 150 local grassland plots in three regions in Germany. Specifically we asked whether PD decreases with land-use intensification and if so, whether the relationship is robust across different regions. Overall, we found that species richness decreased along land-use gradients the results however differed for common and rare species assemblages. PD only weakly decreased with increasing land-use intensity. The strength of the relationship thereby varied among regions and PD metrics used. From our results we suggest that there is no general relationship between PD and land-use intensification probably due to lack of phylogenetic conservatism in land-use sensitive traits. Nevertheless, we suggest that depending on specific regional idiosyncrasies the consideration of PD as a complement to other measures of diversity can be useful.

Quantitative analysis of fitness costs associated with the development of resistance to the Bt toxin Cry1Ac in Helicoverpa armigera.

Transgenic Bacillus thuringiensis (Bt) crops play an increasing role in pest control, and resistance management is a major issue in large-scale cultivation of Bt crops. The fitness cost of resistance in targeted pests is considered to be one of the main factors delaying resistance when using the refuge strategy. By comparing 10 resistant Helicoverpa armigera (Hubner) strains, showing various resistance levels to Bt toxin (Cry1Ac), to a susceptible strain, we showed an increasing fitness cost corresponding with increasing levels of resistance. The relationship between overall fitness cost C and the resistance ratio Rr could be described by C = 24.47/(1 + exp([1.57 - Log10Rr]/0.2)). This model predicted that the maximum overall fitness cost would be ~24% (±5.22) in the strains with the highest resistance level. The overall fitness cost was closely linked to egg hatching rate, fecundity, emergence rate, larval survival rate, and developmental duration of adults. Among fitness components measured, fecundity was the most sensitive trait linked to the resistance selection. To integrate the results into simulation models would be valuable in evaluating how variation in fitness cost may influence the development of resistance in pest populations, thus helping to develop enhanced refuge strategies.

The interaction between personality traits, emotional intelligence and environmentally sensitive management: A research on central Anatolian companies

Businesses cannot act independent of their environment. The dynamic structure of interaction with the internal and external environment forces companies to act more sensitive to environmental issues. In recent years, the importance of environmental problems for economic progress has emerged. Sustainable development models have become directly relevant to environmental factors, and environmental consciousness has increased in all developed countries. Not only large, multinational production companies, but also all actors within the economy, have started to transform their structures in harmony with nature. Businesses are converting into organic structures, which are compatible with the ecosystem. This research was inaugurated to determine the interaction between emotional intelligence and the understanding of environmental consciousness personality traits in businesses. In this study, it is researched the relationship between emotional intelligence and environmental consciousness of the managers in Central Anatolian companies. These companies are, according to the Istanbul Chamber of Commerce, were among the largest 500 companies in Turkey between 2008-2012. Personality traits, emotional intelligence and environmental consciousness are literally reviewed. Then whether similar studies done previously or not were investigated. The study suggests that today's managers should take into account that emotions are directly related to environmentally sensitive business applications. In this regard, environmentally sensitive personality traits should be identified and businesses take these traits into account while recruiting managers. This study also serves as initial research in Turkey on personality traits, emotional intelligence and environmental consciousness.

MAIZE RESPONSE TO DIFFERENT WATER, SALINITY AND NITROGEN LEVELS: AGRONOMIC BEHAVIOR

Soil water, salinity and nitrogen content are three major factors affecting crop production in arid and semi-arid areas. This study was performed in two years of 2009 and 2010 in a semi-arid area in order to investigate the effects of irrigation water quantity (as main plot), quality (saline water, as sub-plot), nitrogen fertilizer (as sub-sub plot) and their interactions on growth and yield of maize hybrid SC704. The experimental design was split plot with three replications. Irrigation treatments consisted of I1 (1.0 crop evapotranspiration (ETc) + 0.25ETc as leaching), I2 (0.75I1) and I3 (0.5I1) applied at 7-day intervals. The salinity treatments were 0.6 (fresh water), 2.0 and 4.0 dS m -1 . There were also three nitrogen (N) treatments including 0, 150 and 300 kg N ha -1 . The results showed that maize under water and salinity stress had longer vegetative stage period by 11 and 16% compared to the control, respectively. The most sensitive trait under water, salinity and nitrogen stress was grain yield (GY) which reduced by 52.3, 25.2 and 28.0%, for treatments of 0.5I1, 4.0 dS m -1 and 0 kg N ha -1 , respectively. Based on water productivity (WP), applied water is more efficient for GY production under lower irrigation and N fertilizer usage. Grain yield surface function approached a maximum under I2 and I1 treatments in response to increasing water and N levels. The contour plots of GY were developed at each salinity level and showed that it could be a useful management device of irrigation and N for maize GY. Based on nitrogen use efficiency (NUE) and nitrogen recovery (NR), the N application rate of 150 kg ha -1 was the optimum rate for the study region especially under saline water conditions. Further, interaction result of the experimental factors showed that with adequate or limited fresh water supply, application of higher N rate (300 kg ha -1 ) yielded higher GY. While under saline

Maize response to water, salinity and nitrogen levels: physiological growth parameters and gas exchange

A split-split-plot design with three replications in two years of 2009 and 2010 was conducted to investigate the effect of different levels of irrigation water (main plot), salinity of irrigation water (sub-plot) and nitrogen fertilizer rate (sub-subplot) on maize growth rate and gas exchange. Irrigation treatments were I1 (1.0 crop evapotranspiration (ETc)+0.25ETc as leaching), I2 (0.75I1) and I3 (0.5I1) applied at 7-day intervals. The salinity treatments of irrigation were 0.6 (fresh water), 2.0 and 4.0 dS m -1 . There were also three nitrogen (N) treatments including 0, 150 and 300 kg N ha -1 . Results showed that vegetative growth stage of maize in salinity stress lasted 5% more than that in water stress. The most sensitive trait under water, salinity and nitrogen stress was grain yield (GY). The optimum treatment for maize production is full fresh water application by 150 kg N ha -1 . Results also showed that crop growth rate (CGR) was statistically higher in I1 and I2 as 58 and 34% relative to I3 treatment, respectively. Furthermore, CGR was statistically lower in S2 and S3 as 10 and 18% relative to S1, respectively. Besides, N application significantly increased CGR by an average of 15% as compared with no N rate. The net assimilation rate (NAR) reached its maximum value in I2, S2 and N2 relative to other treatments indicating that NAR did not necessarily occurred at maximum LAI conditions. In general, maize had statistically greater NAR in pollination and filling stages relative to other growth stages. Results of gas exchange for maize as a sensitive crop to water deficit, showed that photosynthesis rate (An) and stomatal conductance (gs) were statistically decreased in water deficit by an average of 30 and 43% as compared to full irrigation treatment, respectively. However, reduction in An and gs in salinity conditions was the same as 13% compared to no salinity treatment. Transpiration rate (T) was statistically lower under water and salinity stress by an average of 75 and 26% as compared to no water and salinity stress, respectively. The ratio of An/gs in I2 and I3 was

Plastic responses of stem and leaf functional traits in Leymus chinensis to long-term grazing in a meadow steppe

Aims Adaptation of plants to their habitats through phenotypic plasticity in which they trade off various kinds of functional traits is an important ecological strategy. Whereas plant functional traits and its effects on grassland ecosystem functioning have received much attention, the importance of grazing effects on functional traits is poorly understood. This study, therefore, aimed to analyze the responding model of Leymus chinensis functional traits to long-term grazing in semi-arid grassland. Methods The study was conducted in a field experiment involving treatments with various grazing and enclosure schemes in Nei Mongol. We compared the effects of long-term enclosure, short-term enclosure (SE), moderate grazing (MG), and heavy grazing on plant functional traits in L. chinensis. Partial Least Squares Regression was used to analyze the contributions of controlling factors on changes in biomass in response to grazing. Important findings The size of L. chinensis became smaller in plots subject to long-term grazing compared with in the plots of enclosures. It had a significant conservative property of plant dwarf which can be found in the SE plot. Interestingly, the variability increased significantly with the increasing of plasticity index of different functional traits. Also, some functional traits, such as aboveground biomass, plant height, mean leaf length etc., were sensitive traits to grazing. However, other indicators, such as leaf numbers, stem diameter, mean leaf width etc., which were inert functional traits. Stem length, plant height and other traits were main factors which cased the decreasing of L. chinensis aboveground biomass. On the whole, phenotypic change is an important adaptive strategy of L. chinensis to long term grazing.

Definition of the breeding goal and determination of breeding objectives for European wild boar (Sus scrofa L.) in a semi-extensive production system

The objective of this study was to develop the breeding goal for European wild boar under semi-extensive production conditions. The effect of altering production circumstances on economic values was also evaluated. The breeding goal was to improve the production efficiency of the European wild boar in the semi-extensive production system. The traits included in the breeding objective were “protein deposition rate” (PDR), “number born alive” (NBA) and “number of litters per sow per year” (NLY). The bioeconomic model consisted of a breeding herd of 50 sows (produced by the system) and five boars (purchased), with 1.25NLY and five NBA per litter, a maximum number of litters per sow of seven and the boars were kept in the breeding herd for 6.5 years. The live weight at birth was 1.0kg, at weaning 7.0kg and at slaughter 45kg. The average PDR rate was 90gday−1, the proportion of valuable cuts in carcass was 53.8%, and the outputs of the systems consisted of growing animals and culled reproducers. The feeding regime of growing and breeding herds consisted of grazed pasture with a supplemental diet. Alternative scenarios were simulated: an increase or decrease of 20% in the price of the supplemental diet, an increase or decrease of 20% in the final meat price, and the situation of a semi-intensive system. The economic values were 0.0049, 0.0152 and 0.000145 for NBA, NLY and PDR, respectively, expressed as US$ per MJ of digestible energy consumed. The numbers of discounted genetic expressions were 6.062, 6.062 and 2.111, and the economic weights were 0.0298, 0.0924 and 0.00031, for NBA, NLY and PDR, respectively. For all scenarios evaluated, the trend of the economic weights was the same as for the basic situation; NLY had the highest economic value and PDR the lowest. The greatest variations in the basic situation were related to changes in the meat price. The semi-intensive system was most sensitive to the PDR economic weight. Moreover, the determined relative economic weights showed that the most important trait in the semi-intensive system was NBA, followed by PDR, and the lowest value was the relative economic weight for NLY. For all scenarios the most sensitive trait was PDR. The economic values for the three traits were positive. The NLY had the greatest and PDR had the lowest economic weight, whereas NBA represented one-third of NYL economic weight.

Independent effects of warming and nitrogen addition on plant phenology in the Inner Mongolian steppe

Phenology is one of most sensitive traits of plants in response to regional climate warming. Better understanding of the interactive effects between warming and other environmental change factors, such as increasing atmosphere nitrogen (N) deposition, is critical for projection of future plant phenology. A 4-year field experiment manipulating temperature and N has been conducted in a temperate steppe in northern China. Phenology, including flowering and fruiting date as well as reproductive duration, of eight plant species was monitored and calculated from 2006 to 2009. Across all the species and years, warming significantly advanced flowering and fruiting time by 0·64 and 0·72 d per season, respectively, which were mainly driven by the earliest species (Potentilla acaulis). Although N addition showed no impact on phenological times across the eight species, it significantly delayed flowering time of Heteropappus altaicus and fruiting time of Agropyron cristatum. The responses of flowering and fruiting times to warming or N addition are coupled, leading to no response of reproductive duration to warming or N addition for most species. Warming shortened reproductive duration of Potentilla bifurca but extended that of Allium bidentatum, whereas N addition shortened that of A. bidentatum. No interactive effect between warming and N addition was found on any phenological event. Such additive effects could be ascribed to the species-specific responses of plant phenology to warming and N addition. The results suggest that the warming response of plant phenology is larger in earlier than later flowering species in temperate grassland systems. The effects of warming and N addition on plant phenology are independent of each other. These findings can help to better understand and predict the response of plant phenology to climate warming concurrent with other global change driving factors.

Interação entre manejo de plantas daninhas e adubação de cobertura no crescimento inicial de Eucalyptus grandis x E. urophylla

Diante da crescente necessidade de realização de boas técnicas de manejo florestal, foi conduzido um experimento de campo com o objetivo de avaliar a possível interação entre o manejo de plantas daninhas e a adubação de cobertura no desenvolvimento de plantas de eucalipto. Os tratamentos foram dispostos em blocos ao acaso, em esquema fatorial 5x3, constituído de cinco situações de controle das plantas daninhas (testemunha "no mato"; testemunha "limpa"; isoxaflutole; glyphosate; isoxaflutole+glyphosate - em pré e pós- emergência, respectivamente) e três doses de adubação de cobertura (0,5 x; x; e 1,5 x, em que x corresponde à dose recomendada para adubação da cultura). No tricentésimo dia após o plantio do eucalipto, a massa de matéria seca de folhas e a massa de matéria seca de caule foram as características mais sensíveis à interferência das plantas daninhas. Quando em convivência com essas plantas, as doses de adubação de cobertura não promoveram grandes alterações nas variáveis supracitadas, indicando a competição da cultura com as plantas daninhas pelo recurso oferecido. Já nos tratamentos que ficaram livres da convivência com as plantas daninhas por todo o período avaliado (testemunha "limpa") ou por grande parte dele (isoxaflutole + glyphosate), a maior dose de adubação de cobertura foi responsável pelos maiores valores de massa de matéria seca de folhas e caule.