1,720,961 research outputs found
Investigating crop ecophysiological response to water stress to improve precision irrigation strategies
Full text linkKiwifruit is a widely cultivated and economically important fruit crop. Italy is one of the largest producers of kiwifruit in the world and its industry plays an important role both nationally and internationally. In recent years, however, kiwifruit plantations and total production in several countries around the world, including Italy, have been threatened by a complex vine physiological decline syndrome triggered by soil water excess and unsuitable conditions. The current climate change scenario has serious implications for crop production and is certainly a new challenge for kiwifruit cultivation in many areas, urgently requiring more sustainable agricultural practices and adaptation strategies.
Kiwifruit is known to be extremely sensitive to climate and irrigation levels, which affect the viability of kiwifruit growing areas. A low physiological tolerance to drought and waterlogging makes the soil water environment important for healthy growth and optimum production of kiwifruit vines.
This thesis then focuses on evaluating the physiological responses of yellow-fleshed kiwifruit to water stress (both deficit and excess), thereby increasing the knowledge useful for implementing more precise irrigation strategies for this crop. Overall, the aims of this thesis were i) to comprehensively describe the physiological responses of yellow-fleshed kiwifruit vines to water stress, which is increasingly occurring due to climate change and improper irrigation management, ii) to implement more precise irrigation for such a sensitive crop in a very challenging environment (also due to the expected impacts of climate change), and iii) to evaluate the tolerance/susceptibility of different kiwifruit rootstocks to water stress in order to identify more tolerant genotypes to abiotic stress in kiwifruit.
First, a field experiment was conducted to evaluate the physiological behavior of yellow-fleshed kiwifruit vines under varying soil water availability in a Mediterranean environment. This study showed that kiwifruit can cope with challenging Mediterranean environmental conditions by precisely managing irrigation, distributing the right amount of irrigation water to meet the vines' water needs at the right time and place. Drought stress was imposed to study the physiological responses of the vines, through the analysis of the diurnal trends of stem water potential and stomatal conductance, identifying the onset of stress. Daily dynamics of soil water availability reduction and root uptake highlighted the importance of water availability in the top soil layers to provide the amount of water needed by the vines. Soil moisture thresholds were identified to provide the most suitable soil water environment and guide irrigation decisions. In addition, plant measurements (i.e., sap flow and trunk water potential) were used in combination with a mechanistic plant model to characterize the hydraulic behavior of kiwifruit vines under different soil water availability conditions (i.e., well-watered and drought stress). As plant variables are monitored continuously, the modelling approach provides valuable information on the hydraulic functioning of vines under field conditions and throughout the season, and shows great potential for the development of irrigation decision support tools.
In a further step, drought and waterlogging induced responses of different kiwifruit rootstocks and scion/rootstock combinations were investigated. The differential response of the investigated genotypes was evaluated through an integrated physiological and phenotyping approach. In particular, image analysis was performed at the ALSIA 'Metapontum Agrobios' research centre (PhenoLab platform), which is part of the European Plant Phenotyping Network and infrastructures. Physiological and image-based phenotyping assessment provided an effective methodology to conduct a screening for more tolerant kiwifruit genotypes to water stress. The 'Bounty' rootstock was identified as the least susceptible to water stress and 'Hayward' and 'D1' as the most susceptible.
The results obtained will hopefully open the way to further studies that will support kiwifruit production in Italy and help to face new challenges in its cultivation
Physiological and image-based phenotyping assessment of waterlogging responses of three kiwifruit rootstocks and grafting combinations
Full text linkIntroduction: Kiwifruit species have a relatively high rate of root oxygen consumption, making them very vulnerable to low root zone oxygen concentrations resulting from soil waterlogging. Recently, kiwifruit rootstocks have been increasingly used to improve biotic and abiotic stress tolerance and crop performance under adverse conditions. The aim of the present study was to evaluate morpho-physiological changes in kiwifruit rootstocks and grafting combinations under short-term waterlogging stress. Methods: A pot trial was conducted at the ALSIA PhenoLab, part of the Phen-Italy infrastructures, using non-destructive RGB and NIR image-based analysis and physiological measurements to identify waterlogging stress indicators and more tolerant genotypes. Three pot-grown kiwifruit rootstocks (‘Bounty 71,’ Actinidia macrosperma—B; ‘D1,’ Actinidia chinensis var. deliciosa—D; and ‘Hayward,’ A. chinensis var. deliciosa—H) and grafting combinations, with a yellow-fleshed kiwifruit cultivar (‘Zesy 002,’ A. chinensis var. chinensis) grafted on each rootstock (Z/B, Z/D, Z/H), were subjected to a control irrigation treatment (WW), restoring their daily water consumption, and to a 9-day waterlogging stress (WL), based on substrate saturation. Leaf gas exchange, photosynthetic activity, leaf temperature, RGB, and NIR data were collected during waterlogging stress. Results: Stomatal conductance and transpiration reached very low values (less than 0.05 mol m−2 s−1 and 1 mmol m−2 s−1, respectively) in both waterlogged D and H rootstocks and their grafting combinations. In turn, leaf temperature was significantly increased and photosynthesis was reduced (1–6 μmol m−2 s−1) from the first days of waterlogging stress compared to B rootstock and combination. Discussion: The B rootstock showed prolonged leaf gas exchange and photosynthetic activity, indicating that it can cope with short-term and temporary waterlogging and improve the tolerance of grafted kiwi vines, which showed a decrease in stomatal conductance 5 days after the onset of stress. Morphometric and colorimetric parameters from the image-based analysis confirmed the greater susceptibility of D and H rootstocks and their grafting combinations to waterlogging stress compared to B. The results presented confirm the role of physiological measurements and enhance that of RGB and NIR images in detecting the occurrence of water stress and identifying more tolerant genotypes in kiwifruit
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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