1,721,049 research outputs found
Narrow rows increase maize grain yield regardless of plant density in a Mediterranean environment
No full textThe spatial distribution of maize plants influences the number of kernels set per plant by modifying the radiation environment during the critical period for kernel number determination. A two-year field experiment was conducted in Sardinia to explore whether, in a Mediterranean environment, a reduction in row distance can have a positive effect on grain yield of full-season maize hybrids and, if it does, whether this effect is also affected by plant density. Treatments were a factorial combination of three plant densities (6, 8 and 10 plants/m2) and two row spacings (35 and 70 cm). Grain yield and grain number benefited from a reduction in row distance from the canonical 70 cm to 35 cm irrespective of plant density and yield level (14.7 t/ha on average in 2021, 9.9 t/ha in 2022 vs 13.7 and 8.8 t/ha with canonical row distance). Row distance did not affect either the coefficient of extinction of radiation or the intercepted photosynthetically active radiation (PAR) during the critical period for grain number determination. The higher grain number per unit area at the smaller row distance translated into a greater grain yield, which cannot solely be attributed to radiation interception and plant growth rate during the period of kernel number determination. Halving the common row distance is a valuable management option for full-season hybrids grown in Mediterranean environments without nitrogen and water limitations as it seems capable of increasing grain yield via an increase in kernel number per unit area, regardless of plant density and yield level
Changes in radiation capture and use in response to the nitrogen status of durum wheat cultivars at different developmental stages
No full textContext: Cereal nitrogen economy throughout the whole crop cycle is a critical driver of biomass and grain production, but while some periods of N deficiency have a detrimental impact on grain yield, others exert no effect. An appropriate indicator of the N nutritional status of a crop is the N nutrition index (NNI). Objective: i. to quantify NNI from mid tillering until anthesis; ii. to analyze its effects on the capture and use of radiation and biomass production; iii. to highlight cultivar variability in these traits. Methods: A three-year field trial was carried out in a Mediterranean climate to assess NNI of four durum wheat (Triticum turgidum ssp. durum Desf.) cultivars grown under three N fertilization rates (0, 80 and 160 kg N ha-1) from mid tillering until anthesis, and analyze its effects on radiation capture (LAI and fraction of intercepted radiation, FIPAR) and use (RUE, Radiation Use Efficiency) Results: The level of N shortage imposed with the N0 treatment increased from a moderate shortage at tillering (NNI = 0.86 on average) to a maximum N stress at anthesis (NNI = 0.45). The relationship between NNI and RUE was linear until booting, but became curvilinear at anthesis.The relative response of LAI to NNI variation was greater than that observed for RUE, but it did not affect proportionally the FIPAR because the LAI values above 2 observed after tillering already assured an FIPAR between 75% and 92%,. Cultivar Aureo was characterized by the greater NNI (frequently above 1), N uptake, and N allocated to pseudo-stems across all developmental stages. Conclusion: All the cultivars shared common relationships between NNI and RUE, LAI and FIPAR, implying that differences between cultivars in RUE, LAI and FIPAR were partly due to their different NNIs and not to a different response to NNI. RUE was more sensitive to NNI variation than radiation interception expressed as FIPAR, but using LAI as a proxy for radiation interception gives opposite results. Implication: Lines with high potential grain protein percentages may be selected early in the season using NNI above 1 as selection criterium. Cultivars, such as Aureo, which are able to store large quantities of N in their vegetative tissues and attain high NNI values at anthesis are penalized in terms of their RUE during the period in which the potential grain number is determined
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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