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1.
Modelling land cover transitions: A solution to the problem of spatial dependence in data 总被引：1，自引：1，他引：1
Raster-based spatial land cover transition models (LCTMs) are widely used in landscape ecology. However, many LCTMs do not account for spatial dependence of the input data, which may artificially fragment the output spatial configuration. We demonstrate the consequences of ignoring spatial dependence, thus assigning probabilities randomly in space, using a simple LCTM. We ran the model from four different initial conditions with distinct spatial configurations and results indicated that, after 20 simulation steps, all of them converged towards the spatial configuration of the random data set. From an ecological perspective this is a serious problem because ecological data often exhibit distinct spatial configuration related to ecological processes. As a solution, we propose an approach (region approach) that accounts for spatial dependence of LCTM input data. Underlying spatial dependence was used to apply spatial bias to probability assignment within the model. As a case study we applied a region approach to a Vegetation Transition Model (VTM); a semi-Markovian model that simulates forest succession. The VTM was applied to approximately 500,000 ha of boreal forest in Ontario, at 1 ha pixel resolution. When the stochastic transition algorithms were applied without accounting for spatial dependence, spatial configuration of the output data became progressively more fragmented. When the VTM was applied using the region approach to account for spatial dependence output fragmentation was reduced. Accounting for spatial dependence in transition models will create more reliable output for analyzing spatial patterns and relating those patterns to ecological processes.This revised version was published online in May 2005 with corrections to the Cover Date. 相似文献
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Abeysinghe Mudiyanselage Prabodha Sammani Dissanayaka Mudiyanselage Saman Kumara Dissanayaka Leanage Kanaka Wolly Wijayaratne William Robert Morrison III 《Journal of insect science (Online)》2020,20(6)
The almond moth Cadra cautella (Walker), a key pest of storage facilities, is difficult to manage using synthetic chemicals. Pheromone-based management methods remain a high priority due to advantages over conventional management practices, which typically use insecticides. Cadra cautella females release a blend of pheromone including (Z, E)-9,12-tetradecadienyl acetate (ZETA) and (Z)-9-tetradecadien-1-yl acetate (ZTA). The effect of these components on mating of C. cautella and how response varies with the population density and sex ratio remain unknown. In this study, the mating status of C. cautella was studied inside mating cages under different ratios of ZETA and ZTA diluted in hexane and at different population sizes either with equal or unequal sex ratio. The lowest percentage of mated females (highest mating disruption [MD] effects), corresponding to roughly 12.5%, was produced by a 5:1 and 3.3:1 ratio of ZETA:ZTA. Populations with equal sex ratio showed the lowest percentage of mated females, at 20% and 12.5% under lower and higher density, respectively. The next lowest percentage of mated females was produced when the sex ratio was set to 1: 2 and 2:1 male:female, with just 25% and 22.5% of moths mated, respectively. This study shows that mating status of C. cautella is influenced by ZETA:ZTA ratio, sex ratio, and population size. This current knowledge would have useful implications for mating disruption programs. 相似文献
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以非洲菊(Gerbera jamesonii L.)品种Amaretto'为试材,研究外源水杨酸(SA)对缓解非洲菊生殖生长期因盐胁迫引起的过氧化伤害作用.在开花前分别用0、0.5和1.0mmol L-1SA对非洲菊植株进行预处理,3d后用100mmol L-1NaCl灌溉,持续2周;对照植株未经NaCl和SA处理.结果表明:盐胁迫处理后,叶片的超氧化物歧化酶(SOD)和过氧化物酶(POD)活性增加,丙二醛(MDA)含量、电解质外渗率和脯氨酸含量提高;外源SA预处理显著降低了盐胁迫植株叶片的MDA含量和电解质外渗率;在外源0.5mmol L-1SA预处理后,植株SOD和POD活性分别是对照的1.4倍和2.4倍;SA预处理后与植株耐盐性相关的生理生化指标呈显著相关,以0.5mmol L-1SA处理增强植株盐胁迫耐性的效果更好.说明外源SA处理能够诱导盐胁迫下非洲菊植株的抗氧化反应,水杨酸将是一种提高园艺作物耐盐性的有效物质. 相似文献
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H. A. C. K. Ariyarathna M. T. K. Gunasekare J. D. Kottawa-Arachchige R. Paskarathevan K. K. Ranaweera M. Ratnayake J. B. D. A. P. Kumara 《Euphytica》2011,181(2):203-215
A comprehensive knowledge on reproductive traits is a prerequisite in utilizing the existing tea germplasm effectively for
crop improvement to develop superior planting material for grower acceptance and market profitability. The Sri Lankan tea
germplasm was characterized based on reproductive traits viz. floral morphology, pollen biology, stigma receptivity and phenology of flowering and fruit set. The variability in floral
morphology, especially the style morphological features, formed phenotypic clines rather than distinct groups. Studies on
pollen biology and stigma receptivity revealed significant variability and asynchrony that could result unequal reproductive
success among the genotypes. Four distinct patterns were predictable among the genotypes based on flower and fruit abundance
and the time of flowering and fruit set. Three well marked flowering periods occurred in February to April, July and in November.
Nonetheless, major flowering period coincided February and March in all the genotypes allowing free crossing between the different
genotypes. Profuse mature fruit crop was obtained in February to May. Approximately 26% success was achieved in tea controlled
hybridization programmes. Fruits carry two seeds on average and became mature in 8–9 months after pollination. Zygotic development
in tea takes more than 1 month after pollination and early embryonic development continued for 4 months after pollination.
The indexing of the morpho-physiological diversity and the phenological calendars of flowering and fruit set made available
in the study are of significant importance in effective utilization of the tea germplasm for crop improvement. 相似文献
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We assessed the impact of forest management on woodpecker community structure sub-Himalayan dipterocarp sal (Shorea robusta) forests. We selected eight sites representing four management-based ‘forest types’ (natural unworked sal, old- and young managed sal, and teak plantations). At each site, bird surveys were conducted along 2-km-long transects, 20 times during breeding and non-breeding seasons. Habitat characteristics were enumerated using circular and belt plots. Species composition across forest types was compared using multi-response permutation procedures. Indicator analysis identified woodpecker species preferring particular forest types. Biomass, abundance, and mean species richness of woodpeckers were highest in natural sal, intermediate in managed sal, and lowest in teak. There were apparent differences in woodpecker densities between seasons. Densities were higher in breeding season than non-breeding season for natural sal, while the opposite was true for managed sal. Woodpecker species composition significantly differed across forest types. The four largest species, including grey-headed (Picus canus) and greater yellownape (Picus flavinucha) that were identified as indicators, predominated natural sal but were scarce in other types. At a broader level, mean species richness of woodpeckers strongly indicated mean richness of other avifauna during breeding season. Our study suggests that forest management has significantly altered the sub-Himalayan woodpecker community structure. Managed sal forests, particularly teak plantations, are largely unable to support the original woodpecker assemblage during breeding season, although they provide foraging grounds during non-breeding season. 相似文献
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A. Ajith M. T. Labuschagne A. F. Malan A. van Biljon B. Wentzel 《Cereal Chemistry》2010,87(5):393-397
The application of nitrogen (N) fertilizer in malting barley is necessary to obtain good yield, but it also influences kernel protein content, which affects malting quality. The negative correlation between kernel protein content and malting extract is due to the hordein proteins. The aim of this study was to determine the effect of N application timing on hordein fractions and how this influences malt quality. Reversed‐phase high‐performance liquid chromatography (RP‐HPLC) was used to determine the hordein fractions in the two‐ and six‐row barley parents and their doubled‐haploid progeny, for two seasons for one location, and two locations in the second season. There were no changes in hordein level in response to timing of N application over years and locations. The two‐row parent had the lowest hordein level and the six‐row progeny had the highest. Total hordein content of the two‐row progeny and six‐row parent were similar. The supply of additional N in the form of fertilizer rather than the timing of all N applications influenced the production of all hordein fractions. There were significant correlations between hordein fractions and malting quality that also were reported in other studies. Kernel plumpness showed significant negative correlations with D, C, and B hordeins and total hordein content when half of the fertilizer was applied at planting and the other half at the six‐leaf stage. Absorption showed significant positive correlation with C hordeins and a negative correlation with the B‐to‐C ratio, also when the second half of the N was given at the six‐leaf stage. 相似文献
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Determination of growth,colour and other traits in F1 hybrid of Amphiprion percula (male) × A. ocellaris (female) 
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下载免费PDF全文 Jeyagoby Balamurugan Thipramalai Thangappan Ajith Kumar Kandasamy Kathiresan Bharathiamma Meenakumari 《Aquaculture Research》2017,48(6):2989-3003
This study reported the traits values such as colour, feed conversion ratio (FCR), specific growth rate (SGR) and fluorescence capacity of F1 hybrids of Amphiprion percula (male) and A. ocellaris (female). The hybrids exhibited significant variation in FCR (3.63 ± 0.56) and SGR (3.63% ± 0.44) compared with the pure breeds, A. percula (3.12 ± 0.42; 2.80% ± 0.42) and A. ocellaris (3.17 ± 0.43; 3.02% ± 0.19). An exponential relationship was found between FCR and SGR in both the breeds. Image analysis displayed a better colour performance of hybrid than the pure breeds. Individual body parts of the hybrid and pure breeds showed significant colour variation between each other. However, colour contrast of whole body of hybrid was found closer to A. ocellaris in hue cone and towards A. percula in saturation and brightness values. Hence, hybrid displays combination colour reflexion of both the parents. The total pigment content of hybrid (65.71 μg g?1 ± 2.81) was found higher than A. ocellaris (62.01 μg g?1 ± 2.29) and A. percula (56.71 μg g?1 ± 2.56). Further, the spectroflurometric analysis revealed that the both hybrid and pure breeds having poor fluorescence on skin pigmentation. A direct positive heterosis was observed on the SGR, FCR, total pigment and spawning frequency, while negative effect was noted on total length of newly hatched larvae (TL), fertilization rate (FrR), hatching rate (HR), deformation rate (DFR) and survival rate (SR). Hence, multiple cross‐breeding programmes will help in developing high‐quality traits in successive generations. 相似文献
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Mallappa Kumara Swamy Sudipta Kumar Mohanty Maniyam Anuradha 《Journal of Crop Science and Biotechnology》2014,17(2):71-78
The effect of plant growth regulators and natural supplements on the morphogenetic response of Pogostemon cablin Benth. was investigated. Murashige and Skoog (MS) media supplemented with 0.5 mg L?1 benzyl-6-adenine and 0.5 mg L?1 kinetin was effective in inducing multiple shoots (63.20 ± 0.15) with an average shoot length of 5.27 ± 0.15 cm and biomass of 5.20 ± 0.10 g shoot?1. Among the natural supplements, 10% coconut water supplemented to MS media showed a better response in all the morphological parameters studied. The use of 10% tomato extract, 20% banana extract, 10% carrot extract, and 10% papaya extract in MS medium have efficiently increased multiple shoots, shoot length, and fresh weight of the shoots. The natural supplements also effectively increased the chlorophyll content, total protein, and total carbohydrate content in the plant. The frequency of rooting (93%) was highest when shoots were implanted on 1/2 strength MS media with 100 mg L?1 activated charcoal. The in vitro rooted plants were successfully acclimatized and established in soil. Also, RAPD analysis showed no variation suggesting true-to-type nature of the micropropagated plants. Hence, this protocol can effectively reduce the cost of in vitro multiplication of plants. 相似文献
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Pathogenic variability of different isolates of Colletotrichum falcatum Went. collected from six varieties: Co 419, CoC 671 (from Andhra Pradesh), Co 86032, Co87044, 89V74, and a local variety in Bhadrak (from Orissa) were established. Six red rot isolates were differentiated into four distinct pathotypes, viz., pathotype A - Cf 419 and Cf Bdkh; pathotype B - Cf 671; pathotype C - Cf 89V74 and pathotype D - Cf 86032, and Cf 87044. Pathotype A showed a susceptible reaction to Khakai, CoC 671, CoJ 64, and Co 419. Also pathotype B showed a susceptible reaction to Baragua, CoC 671, Co 997, CoJ 64, Co 1148, and Co 975, whereas pathotype C showed a susceptible reaction to CoC 671, Co 7717, Co 997, CoJ 64, Co 975, and Co 419. But pathotype D showed a susceptible reaction to CoC 671 and Co 997. Polymerase chain reaction (PCR) amplification and subsequent restricted fragment length polymorphism (RFLP) analysis of internal transcribed spacer region of ribosomal DNA (rDNA) of Cf 89V74, Cf 671 and Cf Vittal (C. falcatum isolate from Vittal, Karnatak) by four restriction enzymes, Alu I, Msp I, Rsa I, and Pvu II revealed two distinct groups viz.Group 1- Cf 89V74 and Cf Vittal; Group 2-Cf 671. Restriction enzymes Alu I, Msp I, Rsa 1, and Pvu II produced fragment lengths of 380, 520, 550, and 580 bp for Cf Vittal and Cf 89V74, whereas fragment lengths of 420, 370, 440, and 460 bp were observed in Cf 671, respectively. The present investigation with the red rot infected sugarcane samples clearly indicated the existence of two pathotypes viz., pathotype A and pathotype B in Andhra Pradesh and three pathotypes viz., pathotype A, pathotype C, and pathotype D in Orissa. Pathotype C (Cf 89V74) showed similar ITS-RFLP pattern in Cf Vittal which was isolated from Karnataka. 相似文献