scholarly journals Field evaluation of Hevea brasiliensis clones for the incidence of white root disease in Nigeria

Author(s):  
Emmanuel O. Akpaja ◽  
Nicholas O. Ogbebor

Incidence and severity of white root disease affecting rubber trees were determined in ûve rubber clones of 10 and 35 years old. The percentage of infection, aggregate failure, level of infectivity and gross economic loss were evaluated. There were variations in resistance to white root disease among rubber clones studied. However, no rubber clone was free from this disease even though there were signiûcant (P>0.05) differences in the ability of the pathogen to attack different clones. Results of disease index in the multiclonal plot were compared with those from plots of specific clones of rubber. Percentage infection in 35-year-old rubber plots was signiûcantly (P>0.05) higher than 10-year-old rubber trees. The level of infectivity of white root disease pathogen was generally high with the lowest value for missing stands of 3.33 ± 1.67 (representing 41.63 per cent of expected neighbouring stands) and as many as 6.00 ± 0.56 (representing 75 per cent of expected neighbouring stands) in 10 and 35-year-old rubber plots, respectively. The estimated gross economic losses (N 113,652.30 to 274,734.30) per year recorded in the study were high. This study indicates the need for regular monitoring of white root disease in rubber plantations so that the disease can be managed and controlled at an early stage of the disease occurrence.

Author(s):  
Jibo Chen ◽  
Keyao Chen ◽  
Guizhi Wang ◽  
Rongrong Chen ◽  
Xiaodong Liu ◽  
...  

Econometrics and input–output models have been presented to construct a joint model (i.e., an EC + IO model) in the paper, which is characterized by incorporating the uncertainty of the real economy with the detailed departmental classification structure, as well as adding recovery period variables in the joint model to make the model dynamic. By designing and implementing a static model, it is estimated that the indirect economic loss for the transportation sector caused by representative haze pollution of Beijing in 2013 was 23.7 million yuan. The industrial-related indirect losses due to the direct economic losses incurred by haze pollution reached 102 million yuan. With the constructed dynamic model, the cumulative economic losses for the industrial sectors have been calculated for the recovery periods of different durations. The results show that: (1) the longer the period that an industrial department returns to normal output after haze pollution has impacted, the greater the cumulative economic loss will be; (2) when the recovery period is one year, the cumulative economic loss value computed by the dynamic EC + IO model is much smaller than the loss value obtained by the static EC + IO model; (3) the recovery curves of industrial sectors show that the recovery rate at the early stage is fast, while it is slow afterwards. Therefore, the governance work after the occurrence of haze pollution should be launched as soon as possible. This study provides a theoretical basis for evaluating the indirect economic losses of haze pollution and demonstrates the value of popularization and application.


Author(s):  
R. Horrell ◽  
A.K. Metherell ◽  
S. Ford ◽  
C. Doscher

Over two million tonnes of fertiliser are applied to New Zealand pastures and crops annually and there is an increasing desire by farmers to ensure that the best possible economic return is gained from this investment. Spreading distribution measurements undertaken by Lincoln Ventures Ltd (LVL) have identified large variations in the evenness of fertiliser application by spreading machines which could lead to a failure to achieve optimum potential in some crop yields and to significant associated economic losses. To quantify these losses, a study was undertaken to calculate the effect of uneven fertiliser application on crop yield. From LVL's spreader database, spread patterns from many machines were categorised by spread pattern type and by coefficient of variation (CV). These patterns were then used to calculate yield losses when they were combined with the response data from five representative cropping and pastoral situations. Nitrogen fertiliser on ryegrass seed crops shows significant production losses at a spread pattern CV between 30% and 40%. For P and S on pasture, the cumulative effect of uneven spreading accrues, until there is significant economic loss occurring by year 3 for both the Waikato dairy and Southland sheep and beef systems at CV values between 30% and 40%. For nitrogen on pasture, significant loss in a dairy system occurs at a CV of approximately 40% whereas for a sheep and beef system it is at a CV of 50%, where the financial return from nitrogen application has been calculated at the average gross revenue of the farming system. The conclusion of this study is that the current Spreadmark standards are a satisfactory basis for defining the evenness requirements of fertiliser applications in most circumstances. On the basis of Spreadmark testing to date, more than 50% of the national commercial spreading fleet fails to meet the standard for nitrogenous fertilisers and 40% fails to meet the standard for phosphatic fertilisers.Keywords: aerial spreading, crop response, economic loss, fertiliser, ground spreading, striping, uneven application, uneven spreading, yield loss


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yan Hong ◽  
Jingjing Fu ◽  
Dehui Kong ◽  
Siqi Liu ◽  
Zhu Zhong ◽  
...  

Abstract Background With the development of digital media, online activities are increasingly becoming part of the daily life of older adults. Widowed older adults generally would face changes in social interactions and activities due to widowhood; thus, the importance of online participation may be more prominent in this population. However, a detailed evidence on the experiences of online social participation among widowed older adults is relatively sparse. This study aimed to explore widowed older adults’ perceptions regarding online social participation in southwestern China. Methods This study adopted a qualitative approach. Semi-structured, in-depth individual interviews were conducted with 19 widowed older adults between September–December 2020. Thematic analysis was applied to analyse the data. Results Two major themes, “benefits” and “barriers” were identified from the original data analysis. Subcategories concerning the theme “benefits” were “benefit perception (convenience, flexible time, supplementation)”, “health promotion”, “emotional comfort”, and “social connection”. Subcategories of “barriers” were “worries: personal economic loss”, “concerns: security of digital device”, “troubles: the diversity of online social participation”, and “difficulties: using digital media”. Conclusions Social participation of widowed older adults in southwestern China has begun to be integrated into the digital world; however, it remains at an early stage with the simple purpose of engagement. The older adults may face many challenges for online social participation. Although there are barriers and challenges in online social participation, widowed older adults can reap its benefits, which can be used as an important measure to facilitate a fulfilling life and successful ageing. There is no doubt that online social participation will become a trend within the foreseeable future. Family, friends and health care professionals should pay more attention to the needs of online social participation in widowed older adults and provide adequate support for them to achieve a meaningful life.


2021 ◽  
Vol 13 (6) ◽  
pp. 3364
Author(s):  
Amr Zeedan ◽  
Abdulaziz Barakeh ◽  
Khaled Al-Fakhroo ◽  
Farid Touati ◽  
Antonio S. P. Gonzales

Soiling losses of photovoltaic (PV) panels due to dust lead to a significant decrease in solar energy yield and result in economic losses; this hence poses critical challenges to the viability of PV in smart grid systems. In this paper, these losses are quantified under Qatar’s harsh environment. This quantification is based on experimental data from long-term measurements of various climatic parameters and the output power of PV panels located in Qatar University’s Solar facility in Doha, Qatar, using a customized measurement and monitoring setup. A data processing algorithm was deliberately developed and applied, which aimed to correlate output power to ambient dust density in the vicinity of PV panels. It was found that, without cleaning, soiling reduced the output power by 43% after six months of exposure to an average ambient dust density of 0.7 mg/m3. The power and economic loss that would result from this power reduction for Qatar’s ongoing solar PV projects has also been estimated. For example, for the Al-Kharasaah project power plant, similar soiling loss would result in about a 10% power decrease after six months for typical ranges of dust density in Qatar’s environment; this, in turn, would result in an 11,000 QAR/h financial loss. This would pose a pressing need to mitigate soiling effects in PV power plants.


2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ze Peng ◽  
Yanhong He ◽  
Saroj Parajuli ◽  
Qian You ◽  
Weining Wang ◽  
...  

AbstractDowny mildew (DM), caused by obligate parasitic oomycetes, is a destructive disease for a wide range of crops worldwide. Recent outbreaks of impatiens downy mildew (IDM) in many countries have caused huge economic losses. A system to reveal plant–pathogen interactions in the early stage of infection and quickly assess resistance/susceptibility of plants to DM is desired. In this study, we established an early and rapid system to achieve these goals using impatiens as a model. Thirty-two cultivars of Impatiens walleriana and I. hawkeri were evaluated for their responses to IDM at cotyledon, first/second pair of true leaf, and mature plant stages. All I. walleriana cultivars were highly susceptible to IDM. While all I. hawkeri cultivars were resistant to IDM starting at the first true leaf stage, many (14/16) were susceptible to IDM at the cotyledon stage. Two cultivars showed resistance even at the cotyledon stage. Histological characterization showed that the resistance mechanism of the I. hawkeri cultivars resembles that in grapevine and type II resistance in sunflower. By integrating full-length transcriptome sequencing (Iso-Seq) and RNA-Seq, we constructed the first reference transcriptome for Impatiens comprised of 48,758 sequences with an N50 length of 2060 bp. Comparative transcriptome and qRT-PCR analyses revealed strong candidate genes for IDM resistance, including three resistance genes orthologous to the sunflower gene RGC203, a potential candidate associated with DM resistance. Our approach of integrating early disease-resistance phenotyping, histological characterization, and transcriptome analysis lay a solid foundation to improve DM resistance in impatiens and may provide a model for other crops.


Insects ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 559
Author(s):  
Hao Li ◽  
Fang-Fang Liu ◽  
Li-Qing Fu ◽  
Ze Liu ◽  
Wen-Ting Zhang ◽  
...  

Insect C-type lectins (CTLs) play vital roles in modulating humoral and cellular immune responses. The oriental armyworm, Mythimna separata (Walker) (Lepidoptera: Noctuidae) is a migratory pest that causes significant economic loss in agriculture. CTLs have not yet been systematically identified in M. separata. In this study, we first constructed a transcriptome of M. separata larvae, generating a total of 45,888 unigenes with an average length of 910 bp. Unigenes were functionally annotated in six databases: NR, GO, KEGG, Pfam, eggNOG, and Swiss-Prot. Unigenes were enriched in functional pathways, such as those of signal transduction, endocrine system, cellular community, and immune system. Thirty-five unigenes encoding C-type lectins were identified, including CTL-S1~CTL-S6 (single CRD) and IML-1~IML-29 (dual CRD). Phylogenetic analyses showed dramatic lineage-specific expansions of IMLs. Sequence alignment and structural modeling identified potential ligand-interacting residues. Real-time qPCR revealed that CTL-Ss mainly express in eggs and early stage larvae, while IMLs mainly express in mid-late-stage larvae, pupae, and adults. In naïve larvae, hemocytes, fat body, and epidermis are the major tissues that express CTLs. In larvae challenged by Escherichia coli, Staphylococcus aureus, or Beauveria bassiana, the expression of different CTLs was stimulated in hemocytes, fat body and midgut. The present study will help further explore functions of M. separata CTLs.


2021 ◽  
Vol 13 (10) ◽  
pp. 1975
Author(s):  
Lin Wang ◽  
Yuzhen Zhou ◽  
Qiao Hu ◽  
Zhenghong Tang ◽  
Yufeng Ge ◽  
...  

Woody plant encroachment into grasslands ecosystems causes significantly ecological destruction and economic losses. Effective and efficient management largely benefits from accurate and timely detection of encroaching species at an early development stage. Recent advances in unmanned aircraft systems (UAS) enabled easier access to ultra-high spatial resolution images at a centimeter level, together with the latest machine learning based image segmentation algorithms, making it possible to detect small-sized individuals of target species at early development stage and identify them when mixed with other species. However, few studies have investigated the optimal practical spatial resolution of early encroaching species detection. Hence, we investigated the performance of four popular semantic segmentation algorithms (decision tree, DT; random forest, RF; AlexNet; and ResNet) on a multi-species forest classification case with UAS-collected RGB images in original and down-sampled coarser spatial resolutions. The objective of this study was to explore the optimal segmentation algorithm and spatial resolution for eastern redcedar (Juniperus virginiana, ERC) early detection and its classification within a multi-species forest context. To be specific, firstly, we implemented and compared the performance of the four semantic segmentation algorithms with images in the original spatial resolution (0.694 cm). The highest overall accuracy was 0.918 achieved by ResNet with a mean interaction over union at 85.0%. Secondly, we evaluated the performance of ResNet algorithm with images in down-sampled spatial resolutions (1 cm to 5 cm with 0.5 cm interval). When applied on the down-sampled images, ERC segmentation performance decreased with decreasing spatial resolution, especially for those images coarser than 3 cm spatial resolution. The UAS together with the state-of-the-art semantic segmentation algorithms provides a promising tool for early-stage detection and localization of ERC and the development of effective management strategies for mixed-species forest management.


2012 ◽  
Vol 594-597 ◽  
pp. 2272-2276
Author(s):  
Shi Gui Li ◽  
Qing Lin Yi ◽  
Juan Juan Wu

China is one of the most serious national which does harm to geological disasters, and the geological disasters have effect on China’s economy. Therefore, the effective evaluation for the economic losses caused by geological disasters has some reference value. This paper mainly introduces the geological disaster economic losses structure drawing and evaluated methods which include human capital method, shadow valuation method, market valuation method, investigation appraisal method and coefficient of proportionality method, and analyzes different economic losses should adopt different appraisal method. And take the Qianjiangping landslide for instant, this paper introduces how to evaluate landslide disasters economic loss. The idea and method have certain guiding significance to geological disaster economic losses evaluation.


2021 ◽  
Author(s):  
Ting Cao

Abstract In recent years, long-term exposure to ambient fine particulate matter (PM2.5) has slowly increased both morbidity and mortality for Chinese people, becoming a leading problem for public health efforts. However, spatial-temporal dynamics of disease burden attributable to PM2.5 exposure still lacks a comprehensive evaluation so as to provide inadequate supports for policy making and improvement. Here, we used the exposure-response function to derive the spatial-temporal dynamics of disease burden attributable to PM2.5 pollution in China. We found the fact that economic loss attributable to PM2.5 increased by 93% from 35 billion Chinese Yuan (95% CI: 14-52) to 536 billion Chinese Yuan (95%CI: 236-753) during the period of 16 years. Digging further, we discovered a substantiate level of regional differences, with the disease burden being the most severe in East China and the least severe in the Northwest China. Other than that, there existed a spatial aggregation of health-related economic losses among Chinese cities. Our paper made an evaluation on the spatial-temporal dynamics of health effects attributed to PM2.5, an evaluation that could provide more insights to future policy making of the air pollution control for China and other developing countries.


2013 ◽  
Vol 13 (10) ◽  
pp. 2679-2694 ◽  
Author(s):  
M. Gil ◽  
A. Garrido ◽  
N. Hernández-Mora

Abstract. The economic evaluation of drought impacts is essential in order to define efficient and sustainable management and mitigation strategies. The aim of this study is to evaluate the economic impacts of a drought event on the agricultural sector and measure how they are transmitted from primary production to industrial output and related employment. We fit econometric models to determine the magnitude of the economic loss attributable to water storage. The direct impacts of drought on agricultural productivity are measured through a direct attribution model. Indirect impacts on agricultural employment and the agri-food industry are evaluated through a nested indirect attribution model. The transmission of water scarcity effects from agricultural production to macroeconomic variables is measured through chained elasticities. The models allow for differentiating the impacts deriving from water scarcity from other sources of economic losses. Results show that the importance of drought impacts are less relevant at the macroeconomic level, but are more significant for those activities directly dependent on water abstractions and precipitation. From a management perspective, implications of these findings are important to develop effective mitigation strategies to reduce drought risk exposure.


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