Effects of brodifacoum and diphacinone exposure on four species of reptiles: tissue residue levels and survivorship     

Richard E Mauldin  Gary W Witmer  Susan A Shriner  Rachael S Moulton  Katherine E Horak 《Pest management science》2020,76(5):1958-1966

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Adoption and Impact of Modern Rice Varieties on Poverty in Eastern India     

Kwasi Bannor Richard  Amarnath Krishna Kumar Gupta  Oppong-Kyeremeh Helena  Abawiera Wongnaa Camillus 《水稻科学》2020,27(1):56-66

The factors affecting the adoption of modern varieties(MVs) of rice and impact on poverty in Odisha, India were discussed. A total of 363 households from Cuttack and Sambalpur districts of Odisha via multistage sampling technique participated in the survey. The Cragg's Double hurdle model was used to model the determinants of adoption and intensity of adoption of MVs of rice, and the propensity score matching was used to analyze the impact of adoption on poverty. The results showed that age, education, risk aversion, land size, yield, perception of MVs as high yielding, resistant to diseases and availability of MVs positively influenced the decision to adopt. However, variables such as household size, experience of a farmer, off-farm job participation, amount of credit received, cost of seeds, insecticides and fertilizers negatively influenced the adoption of MVs. Intensity of adoption of MVs was negatively influenced by experience of a farmer, cost of fertilizer and marketability of MVs, and positively affected by household size, risk aversion, land size, cost of insecticides, perception of MVs as high yielding and availability of MV seeds. Poverty incidence, gap and severity were high among non-adopters to adopters of MVs. After matching adopters and non-adopters of MV groups using four different algorithms of nearest neighbour matching, stratification matching, radius matching and kernel matching, the impact of MV adoption resulted in higher per capita monthly household expenditure by about US$ 52.82 to US$ 63.17.  相似文献   

Cherry picking by pseudomonads: After a century of research on canker,genomics provides insights into the evolution of pathogenicity towards stone fruits     

Michelle T. Hulin  Robert W. Jackson  Richard J. Harrison  John W. Mansfield 《Plant pathology》2020,69(6):962-978

Bacterial canker disease is a major limiting factor in the growing of cherry and other Prunus species worldwide. At least five distinct clades within the bacterial species complex Pseudomonas syringae are known to be causal agents of the disease. The different pathogens commonly coexist in the field. Reducing canker is a challenging prospect as the efficacy of chemical controls and host resistance may vary against each of the diverse clades involved. Genomic analysis has revealed that the pathogens use a variable repertoire of virulence factors to cause the disease. Significantly, strains of P. syringae pv. syringae possess more genes for toxin biosynthesis and fewer encoding type III effector proteins. There is also a shared pool of key effector genes present on mobile elements such as plasmids and prophages that may have roles in virulence. By contrast, there is evidence that absence or truncation of certain effector genes, such as hopAB, is characteristic of cherry pathogens. Here we highlight how recent research, underpinned by the earlier epidemiological studies, is allowing significant progress in our understanding of the canker pathogens. This fundamental knowledge, combined with emerging insights into host genetics, provides the groundwork for development of precise control measures and informed approaches to breed for disease resistance.  相似文献   

Using an unmanned aerial vehicle to evaluate nitrogen variability and height effect with an active crop canopy sensor     

Brian Krienke  Richard B. Ferguson  Michael Schlemmer  Kyle Holland  David Marx  Kent Eskridge 《Precision Agriculture》2017,18(6):900-915

Ground-based active sensors have been used in the past with success in detecting nitrogen (N) variability within maize production systems. The use of unmanned aerial vehicles (UAVs) presents an opportunity to evaluate N variability with unique advantages compared to ground-based systems. The objectives of this study were to: determine if a UAV was a suitable platform for use with an active crop canopy sensor to monitor in-season N status of maize, if UAV’s were a suitable platform, is the UAV and active sensor platform a suitable substitute for current handheld methods, and is there a height effect that may be confounding measurements of N status over crop canopies? In a 2013 study comparing aerial and ground-based sensor platforms, there was no difference in the ability of aerial and ground-based active sensors to detect N rate effects on a maize crop canopy. In a 2014 study, an active sensor mounted on a UAV was able to detect differences in crop canopy N status similarly to a handheld active sensor. The UAV/active sensor system (AerialActive) platform used in this study detected N rate differences in crop canopy N status within a range of 0.5–1.5 m above a relatively uniform turfgrass canopy. The height effect for an active sensor above a crop canopy is sensor- and crop-specific, which needs to be taken into account when implementing such a system. Unmanned aerial vehicles equipped with active crop canopy sensors provide potential for automated data collection to quantify crop stress in addition to passive sensors currently in use.  相似文献   

Identification and Functional Analysis of Bet v 1 in Three D Genome-containing Wild Cotton Varieties     

Dong Qi  Magwanga Richard Odongo  Lu Pu  Cai Xiaoyan  Zhou Zhongli  Wang Xingfen  Wang Xingxing  Xu Yanchao  Hou Yuqing  Wang Yanqing  Wang Kunbo  Liu Fang  Ma Zhiying 《棉花学报》2019,31(5):361-380

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Resettling,disconnecting or displacing? Attending to local sociality,culture and history in disaster settings     

Minna Hsu  Tetsuya Okada  Suguru Mori  Richard Howitt 《Asia Pacific viewpoint》2019,60(2):163-174

In many disaster settings, top‐down responses emphasise ‘expert‐led’ solutions that often involve relocating disaster‐affected communities. While the intention might be to move people from harm's way and facilitate recovery, failure to attend to local pre‐disaster circumstances as well as the interplay between power, resilience and vulnerability within and around affected communities often sees resettlement reconfigure as displacement or disconnection. This oversight may even usher in a new phase of dispossession and disadvantage for marginalised groups (particularly in colonial settings). This paper explores experiences in Australia, Japan and Taiwan to reflect on what issues of local sociality, local culture and local resilience need to be attended to in framing ‘better’ disaster responses.  相似文献   

Thirty years of change and the future of Alaskan fisheries: Shifts in fishing participation and diversification in response to environmental,regulatory and economic pressures     

Anne H. Beaudreau  Eric J. Ward  Richard E. Brenner  Andrew O. Shelton  Jordan T. Watson  Jennifer C. Womack  Sean C. Anderson  Alan C. Haynie  Kristin N. Marshall  Benjamin C. Williams 《Fish and Fisheries》2019,20(4):601-619

Heterogeneity in human responses and decision‐making can contribute to the resilience of social–ecological systems in the face of environmental, political and economic pressures. In fishery systems worldwide, the ability of harvesters to maintain a diverse portfolio of fishing strategies is important for building adaptive capacity. We used a case‐study approach to examine the complexity of factors that inhibit or promote diversification in fisheries of Alaska, one of the major fishing regions of the world. Through a combination of harvest records and literature review, we explored shifts in participation and portfolio diversity in Alaskan fisheries over three decades. The four case‐studies examined the responses of fishers, fleets and communities to multiple, intersecting pressures, including biological declines, market and price dynamics, fishery privatization and the 1989 Exxon Valdez oil spill. These cases illustrate how stressors acting at multiple scales can encourage or constrain opportunities for diversification, and that these opportunities may be spread inequitably across participants. Overall, we found evidence for reduced participation and increasing specialization in Alaskan commercial fisheries. While numerous factors explain these trends, policies like individual quota systems and the increasing cost of entry into fisheries are forcing consolidation at local to regional scales. A portfolio approach to managing fisheries that reduces barriers to diversification and includes broad representation of resource users and communities in management may help to maintain opportunity and choice for fishers.  相似文献   

Present state of imposex in neptune whelk Neptunea arthritica inhabiting shallow waters around Hokkaido, Japan     

Katsuaki Fujinaga  Anthony S Ilano  Hirotaka Nomura  Richard T Miranda  Shigeru Nakao 《Fisheries Science》2006,72(5):995-1003

ABSTRACT:   The state of imposex in Neptunea arthritica from seven sites along the coast of Hokkaido, Japan was examined in 2002 based on the criteria: (i) relative penis size index (RPSI); (ii) imposex frequency; (iii) stage frequency distribution of imposex in adult and immature whelks; and (iv) sex ratio. RPSI differed from site to site, although values from all sites were low (0.186–5.294). In particular, the RPSI values for four sites were very low (<1.0). In sites where immature whelks were also collected, the frequency of imposex was considerably lower in immature (7.7%–55.6%) than in adult whelks (50%–95.2%) except at one site. The imposex stage frequency distribution also differed among sites, and the trend in the adult whelks corresponded with their RPSI value. Female whelks showing severe imposex (Stage 3 and 3+) were restricted to large individuals.  相似文献   

Fine-scale vegetation patches decline in size and cover with increasing rainfall in Australian savannas   总被引：5，自引：0，他引：5  

Ludwig  John A.  Tongway  David J.  Eager  Robert W.  Williams  Richard J.  Cook  Garry D. 《Landscape Ecology》1999,14(6):557-566

Fine-scale vegetation patches (<5 m in width) are critically important in many landscapes because they function to obstruct surface flows of water and wind. These obstructions increase the infiltration of runoff and the capture of nutrients in runoff sediments and in wind-blown soil and litter. The importance of redistribution of runoff into runon patches from spaces between patches (fetches) is likely to be greater in drier than in wetter environments. In this paper we examine the hypothesis that the ratio of fetch to patch decreases as rainfall increases, and that this trend will be most evident on intermediate-textured soils because these soils are more prone to runoff. We measured fine-scale patches on 38 sites with sand, loam or clay soils. Sites were located along a 1000-mm rainfall gradient in the savannas of northern Australia. The width and intercept length of patches and the fetch between patches was measuring along line transects of 100–120 m oriented down slope. We found that the ratio of fetch to patch area did not decrease with decreasing rainfall, but increased on both sand and loam soils. This result was because with increasing rainfall mean spacing between patches disproportionally increased while mean patch size and cover declined. The cover of patches was negatively correlated with tree canopy cover, which significantly increased with rainfall. This negative correlation suggests that in higher rainfall savannas the size and spacing of ground-layer patches is controlled by the tree layer, and that as rainfall decreases this control decreases and runoff-runon processes increasingly structure the landscape. For savannas on clay soils these trends were not significant except that on the highest rainfall sites the cover of ground-layer patches was nearly 100% while trees were absent.  相似文献   

Der Standort der Lärche innerhalb und autzerhalb ihres natürlichen Verbreitungsgebietes     

Richard Lang 《European Journal of Forest Research》1932,54(3):77-87

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