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Fertilization Treatments (fertilization + treatment)
Selected AbstractsThe Algorithmically Structured Systematic Exploration of Subject's State of Mind: II Reliability and Construct ValidityINTERNATIONAL JOURNAL OF APPLIED PSYCHOANALYTIC STUDIES, Issue 4 2007Marie-Noëlle Le Mer Abstract Objective: To investigate the reliability and validity of a newly developed semistructured interview, the Algorithmically Structured Systematic Exploration of Subject's State of Mind (Assess_Mind). Method: Twelve scales have been developed and used to rate 86 Assess_Mind interviews conducted with patients undergoing in vitro fertilization treatment. For each rating scale, we assessed interrater reliability, interviewer effect, and construct validity. In addition, a factor analysis of scales was performed. To study the validity of scales and of the factors yielded by factor analysis, patients were assessed with a psychopathological battery including the Child Project Questionnaire, the State-Trait Anxiety Inventory, the Perceived Stress Scale, and the Ways of Coping Checklist. Results: For 11 of the 12 scales, interrater reliability was fair to excellent. There was no significant interviewer effect affecting any of the scales. In addition, the validity of nine of these 11 scales was demonstrated by their correlations with questionnaires measuring similar constructs. Conclusion: Nine of the Assess_Mind scales appear to have adequate psychometric properties. Copyright © 2007 John Wiley & Sons, Ltd. [source] Differential genetic influences on competitive effect and response in Arabidopsis thalianaJOURNAL OF ECOLOGY, Issue 5 2005JAMES F. CAHILL JR Summary 1Competition plays an important role in structuring populations and communities, but our understanding of the genetic basis of competitive ability is poor. This is further complicated by the fact that plants can express both competitive effect (target plant influence upon neighbour growth) and competitive response (target plant growth as a function of a neighbour) abilities, with these ecological characteristics potentially being independent. 2Using the model plant species Arabidopsis thaliana, we investigated patterns of intraspecific variation in competitive effect and response abilities and their relationships to other plant traits and resource supply rates. 3Both competitive effect and response were measured for 11 genotypes, including the Columbia ecotype and 10 derived mutant genotypes. Plants were grown alone, with intragenotypic competition, and with intergenotypic competition in a replicated blocked design with high nutrient and low nutrient soil nutrient treatments. We quantified competitive effect and response on absolute and per-gram bases. 4Competitive effect and response varied among genotypes, with the relative competitive abilities of genotypes consistent across fertilization treatments. Overall, high rates of fertilization increased competitive effect and competitive response abilities of all genotypes. Both competitive effect and response were correlated with neighbour biomass, though genotype-specific traits also influenced competitive response. 5At the genotype level, there was no correlation between competitive effect and response in either fertilization treatment. Overall patterns in competitive response appeared consistent among inter- and intragenotypic competition treatments, indicating that a target genotype's response to competition was not driven by the genetic identity of the competitor. 6These findings indicate that within A. thaliana, there is the potential for differential selection on competitive effect and response abilities, and that such selection may influence different sets of plant traits. The concept of a single competitive ability for a given plant is not supported by these data, and we suggest continued recognition of these dual competitive abilities is essential to understanding the potential role of competition in influencing intra- and interspecific processes. [source] Abundance and composition of ammonia-oxidizing bacteria and ammonia-oxidizing archaea communities of an alkaline sandy loamENVIRONMENTAL MICROBIOLOGY, Issue 6 2008Ju-pei Shen Summary The abundance and composition of soil ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) communities under different long-term (17 years) fertilization practices were investigated using real-time polymerase chain reaction and denaturing gradient gel electrophoresis (DGGE). A sandy loam with pH (H2O) ranging from 8.3 to 8.7 was sampled in years 2006 and 2007, including seven fertilization treatments of control without fertilizers (CK), those with combinations of fertilizer nitrogen (N), phosphorus (P) and potassium (K): NP, NK, PK and NPK, half chemical fertilizers NPK plus half organic manure (1/2OMN) and organic manure (OM). The highest bacterial amoA gene copy numbers were found in those treatments receiving N fertilizer. The archaeal amoA gene copy numbers ranging from 1.54 × 107 to 4.25 × 107 per gram of dry soil were significantly higher than those of bacterial amoA genes, ranging from 1.24 × 105 to 2.79 × 106 per gram of dry soil, which indicated a potential role of AOA in nitrification. Ammonia-oxidizing bacteria abundance had significant correlations with soil pH and potential nitrification rates. Denaturing gradient gel electrophoresis patterns revealed that the fertilization resulted in an obvious change of the AOB community, while no significant change of the AOA community was observed among different treatments. Phylogenetic analysis showed a dominance of Nitrosospira -like sequences, while three bands were affiliated with the Nitrosomonas genus. All AOA sequences fell within cluster S (soil origin) and cluster M (marine and sediment origin). These results suggest that long-term fertilization had a significant impact on AOB abundance and composition, while minimal on AOA in the alkaline soil. [source] Quantitative analyses of the abundance and composition of ammonia-oxidizing bacteria and ammonia-oxidizing archaea of a Chinese upland red soil under long-term fertilization practicesENVIRONMENTAL MICROBIOLOGY, Issue 9 2007Ji-zheng He Summary The abundance and composition of soil ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) were investigated by using quantitative real-time polymerase chain reaction, cloning and sequencing approaches based on amoA genes. The soil, classified as agri-udic ferrosols with pH (H2O) ranging from 3.7 to 6.0, was sampled in summer and winter from long-term field experimental plots which had received 16 years continuous fertilization treatments, including fallow (CK0), control without fertilizers (CK) and those with combinations of fertilizer nitrogen (N), phosphorus (P) and potassium (K): N, NP, NK, PK, NPK and NPK plus organic manure (OM). Population sizes of AOB and AOA changed greatly in response to the different fertilization treatments. The NPK + OM treatment had the highest copy numbers of AOB and AOA amoA genes among the treatments that received mineral fertilizers, whereas the lowest copy numbers were recorded in the N treatment. Ammonia-oxidizing archaea were more abundant than AOB in all the corresponding treatments, with AOA to AOB ratios ranging from 1.02 to 12.36. Significant positive correlations were observed among the population sizes of AOB and AOA, soil pH and potential nitrification rates, indicating that both AOB and AOA played an important role in ammonia oxidation in the soil. Phylogenetic analyses of the amoA gene fragments showed that all AOB sequences from different treatments were affiliated with Nitrosospira or Nitrosospira- like species and grouped into cluster 3, and little difference in AOB community composition was recorded among different treatments. All AOA sequences fell within cluster S (soil origin) and cluster M (marine and sediment origin). Cluster M dominated exclusively in the N, NP, NK and PK treatments, indicating a pronounced difference in the community composition of AOA in response to the long-term fertilization treatments. These findings could be fundamental to improve our understanding of the importance of both AOB and AOA in the cycling of nitrogen and other nutrients in terrestrial ecosystems. [source] Mortality in seedling populations of Silver Birch: genotypic variation and herbivore effectsFUNCTIONAL ECOLOGY, Issue 5 2003K. Prittinen Summary 1Variation among mature plants reflects mortality that has occurred during the seedling phase. Our earlier studies have shown variation in resistance to insect and vole herbivory among Silver Birch genotypes that represent variation in a naturally regenerated birch stand. The aim of this study was to examine whether seedling mortality varied among these genotypes, and whether insect and field vole herbivory affected mortality. The 20 genotypes studied competed with each other in dense stands, which were randomly assigned to insect and vole exposure and fertilization treatments. 2Insect herbivory and fertilization increased mortality significantly (by 98 and 68%, respectively). The fertilization effect was probably due to accelerated self-thinning among fast-growing seedlings. Although vole browsing removed considerable biomass, it did not affect seedling mortality. 3Mortality was context-dependent. The genotypes differed both in their overall mortality and in their response to insect herbivory. However, the effect of insects on a genotype depended more on its success in competition than on its resistance: even small amounts of feeding were detrimental to short, shaded seedlings, while taller seedlings in the canopy were affected less, although they were eaten more. 4It is concluded that moderate levels of insect herbivory can increase seedling mortality considerably. Furthermore, herbivory can change the genetic structure of birch populations through selective mortality, which in dense stands is dependent on competitive traits. [source] Fifteen years of climate change manipulations alter soil microbial communities in a subarctic heath ecosystemGLOBAL CHANGE BIOLOGY, Issue 1 2007RIIKKA RINNAN Abstract Soil microbial biomass in arctic heaths has been shown to be largely unaffected by treatments simulating climate change with temperature, nutrient and light manipulations. Here, we demonstrate that more than 10 years is needed for development of significant responses, and that changes in microbial biomass are accompanied with strong alterations in microbial community composition. In contrast to slight or nonsignificant responses after 5, 6 and 10 treatment years, 15 years of inorganic NPK fertilizer addition to a subarctic heath had strong effects on the microbial community and, as observed for the first time, warming and shading also led to significant responses, often in opposite direction to the fertilization responses. The effects were clearer in the top 5 cm soil than at the 5,10 cm depth. Fertilization increased microbial biomass C and more than doubled microbial biomass P compared to the non-fertilized plots. However, it only increased microbial biomass N at the 5,10 cm depth. Fertilization increased fungal biomass and the relative abundance of phospholipid fatty acid (PLFA) markers of gram-positive bacteria. Warming and shading decreased the relative abundance of fungal PLFAs, and shading also altered the composition of the bacterial community. The long time lag in responses may be associated with indirect effects of the gradual changes in the plant biomass and community composition. The contrasting responses to warming and fertilization treatments show that results from fertilizer addition may not be similar to the effects of increased nutrient mineralization and availability following climatic warming. [source] Differential genetic influences on competitive effect and response in Arabidopsis thalianaJOURNAL OF ECOLOGY, Issue 5 2005JAMES F. CAHILL JR Summary 1Competition plays an important role in structuring populations and communities, but our understanding of the genetic basis of competitive ability is poor. This is further complicated by the fact that plants can express both competitive effect (target plant influence upon neighbour growth) and competitive response (target plant growth as a function of a neighbour) abilities, with these ecological characteristics potentially being independent. 2Using the model plant species Arabidopsis thaliana, we investigated patterns of intraspecific variation in competitive effect and response abilities and their relationships to other plant traits and resource supply rates. 3Both competitive effect and response were measured for 11 genotypes, including the Columbia ecotype and 10 derived mutant genotypes. Plants were grown alone, with intragenotypic competition, and with intergenotypic competition in a replicated blocked design with high nutrient and low nutrient soil nutrient treatments. We quantified competitive effect and response on absolute and per-gram bases. 4Competitive effect and response varied among genotypes, with the relative competitive abilities of genotypes consistent across fertilization treatments. Overall, high rates of fertilization increased competitive effect and competitive response abilities of all genotypes. Both competitive effect and response were correlated with neighbour biomass, though genotype-specific traits also influenced competitive response. 5At the genotype level, there was no correlation between competitive effect and response in either fertilization treatment. Overall patterns in competitive response appeared consistent among inter- and intragenotypic competition treatments, indicating that a target genotype's response to competition was not driven by the genetic identity of the competitor. 6These findings indicate that within A. thaliana, there is the potential for differential selection on competitive effect and response abilities, and that such selection may influence different sets of plant traits. The concept of a single competitive ability for a given plant is not supported by these data, and we suggest continued recognition of these dual competitive abilities is essential to understanding the potential role of competition in influencing intra- and interspecific processes. [source] Juvenile shrubs show differences in stress tolerance, but no competition or facilitation, along a stress gradientJOURNAL OF ECOLOGY, Issue 1 2000Lisa A. Donovan Summary 1,We investigated experimentally differences in abiotic stress tolerance and the effects of plant,plant interactions for two desert shrubs, Chrysothamnus nauseosus and Sarcobatus vermiculatus, along a soil salinity (NaCl) and boron (B) gradient at Mono Lake, California, USA. Based on differences in natural distribution, and the classical expectation of a trade-off between competitive ability and stress tolerance, we hypothesized that (i) Chrysothamnus would have greater competitive ability than Sarcobatus at the low salinity end of the gradient, and that (ii) Sarcobatus would be more stress tolerant than Chrysothamnus. 2,Juvenile target plants of Chrysothamnus and Sarcobatus were planted into four sites along the gradient. Biomass was determined by destructive harvests over two growing seasons. At each site, interspecific relative competitive ability was assessed as the effect of Sarcobatus neighbours on Chrysothamnus targets compared to the effect of Chrysothamnus neighbours on Sarcobatus targets. Stress tolerance was assessed as the ability of each species to survive and grow, in the absence of neighbours, at different sites along the gradient. 3,The two species did not differ in the relative strength of plant,plant interactions, providing no support for the expectation that Chrysothamnus had greater competitive ability than Sarcobatus. Furthermore, there was no evidence for competition or facilitation, either interspecific or intraspecific, at any site in either year of the study. However, fertilization treatments demonstrated nutrient limitations, soil water reached limiting levels and root systems of targets and neighbours overlapped substantially. It is therefore surprising that plant,plant interactions among juveniles apparently play little role in the growth and survival of shrubs in this saline desert habitat. 4,Sarcobatus was more stress tolerant than Chrysothamnus and the two species performed optimally at different sites along the gradient. Sarcobatus juveniles grew best at the two most saline sites and survived at all sites, whereas Chrysothamnus juveniles grew best at a low-salinity site and did not survive at the most saline site. The difference in site of optimal performance may be due to differences in nutrient limitations or to interactions between nutrient availability and sodium (Na) and B tolerance. [source] Mulberry nutrient management for silk production in Hubei Province of ChinaJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2009Fang Chen Abstract The silk industry is important for south China's rural economy. Leaves of mulberry (Morus spp.) are used for silkworm production. Hubei province is one of the main silk-producing provinces in China. The objectives of this research were to survey the fertilization practices in the mulberry-producing regions in the province and to determine the best nutrition-management practice for mulberry plantations. A survey and a series of field experiments with N, P, K, and micronutrients were conducted from 2001 to 2002. In addition, a silkworm-growth experiment was also conducted by feeding leaves harvested from various fertilization treatments. The results indicate that poor soil fertility and unbalanced fertilization were the main factors limiting mulberry-leaf yield and quality in Hubei province. Nitrogen fertilization of mulberry has reached a high level (454,kg ha,1 y,1) in Hubei province, but P- and K-fertilization rates have not been matched with N-fertilization rates as farmers are not aware of the significance of P and K. Balanced fertilization showed positive nutrient interactions with respect to mulberry yield and quality. Potassium application increased yield and quality (protein and sugar concentration) of mulberry leaves. Silkworm growth and cocoon quality were improved when silkworms were fed with the leaves derived from K-fertilized plants in comparison with those taken from control plots. Application of Mg, S, and B also significantly improved leaf sugar, essential and total amino acid concentrations, but did not increase leaf yield significantly. It is concluded that a fertilizer dose of 375,kg N ha,1, 66,kg P ha,1, and 125,kg K ha,1 is suitable for the cultivation of mulberry in the Hubei province along with Mg, S, and B, wherever necessary, for the improvement of yield and quality of mulberry leaves. [source] Long-term increase in nitrogen supply alters above- and below-ground ectomycorrhizal communities and increases the dominance of Russula spp. in a temperate oak savannaNEW PHYTOLOGIST, Issue 1 2003Peter G. Avis Summary ,,Here we examine the effects of increased nitrogen (N) supply on the ectomycorrhizal fungal communities of a temperate oak savanna. ,,In a 16-yr N-addition experiment in which replicate 1000 m2 plots received 0, 5.4 or 17 g N m,2 yr,1, ectomycorrhizal sporocarp production was measured in the 14th, 15th and 16th year of fertilization. Ectomycorrhizal fungi (EMF) colonizing roots were examined by morphotyping-PCR-RFLP and sequence analysis in the 14th and 15th year of fertilization. ,,Total sporocarp richness was reduced by > 50% in both fertilization treatments in all 3 yrs, whereas Russula spp. produced approx. five times more sporocarps with 17 g N m,2 yr,1. Below-ground, treatment-scale species richness and species area curves were lower with 17 g N m,2 yr,1 but richness, diversity indices and evenness at smaller spatial scales were not. Dominant fungi colonizing roots included Cenococcum geophilum, common in all treatments, Cortinarius spp., dominant in unfertilized plots, and Russula spp., dominant with 17 g N m,2 yr,1. ,,Communities of EMF in this temperate deciduous ecosystem responded to N addition similarly to those of coniferous ecosystems in that increased N supply altered EMF diversity and community composition but differently in that dominance of Russula spp. increased. [source] Seedling Growth and Heavy Metal Accumulation of Candidate Woody Species for Revegetating Korean Mine SpoilsRESTORATION ECOLOGY, Issue 4 2008Kyung Won Seo Abstract Selecting plant species that can overcome harsh soil and microclimatic conditions and speed the recovery of degraded minelands remains a worldwide restoration challenge. This study evaluated the potential of three woody species and various organic and inorganic fertilization treatments for revegetating abandoned metalliferous mines in Korea. We compared survival, growth, and heavy metal uptake of species common to Korean minelands in two spoil types and a reference forest soil. Substrate type and fertilization both influenced seedling growth and metal concentrations substantially, but they had little effect on seedling survival. Fertilization increased the growth of all three species when grown in mine spoils but influenced the growth of seedlings grown in forest soil only marginally. Initial seedling survival and growth indicate that the study species can tolerate the heavy metal concentrations and other soil constraints of metalliferous spoil types. We estimate that plants can stabilize 2,22% of various heavy metals contained in spoil materials into plant biomass during 20 years of plantation growth. Combined with the erosion control and site amelioration benefits of mineland reforestation, stabilization of heavy metals in forest biomass justifies this treatment on abandoned Korean metalliferous mines. [source] | ||||||||||