1,721,039 research outputs found
Sustainable Weed Control in the Agro-Ecosystems
No full textWorldwide weeds are the cause of the highest potential crop losses (representing on average −34%), even if they are frequently underestimated since more attention is generally paid to dangerous insects (representing on average 18% of yield loss) or pathogens (representing on average 16% of yield loss) [...
Contribution of biochar and arbuscular mycorrhizal fungi to sustainable cultivation of sunflower under semi-arid environment
No full textArbuscular mycorrhizal (AM) fungi and biochar have been successfully adopted to improve crop growth and yield under water stressed environments, however, to date little evidence of their combined effects has been reported. Field trials were conducted in 2018 and 2019 growing seasons in northern Iran to evaluate how biochar and AM fungi could improve sunflower (Helianthus annuus L.) productivity subjected to reduced irrigation regimes. A randomized complete block design was adopted with the following treatments: three irrigation regimes [no deficit irrigation (NDI), moderate deficit irrigation (MDI) and severe deficit irrigation (SDI) that was calculated as the 50, 30, and 10 % of maximum available water, respectively]; three biochar rates [0 (B0), 2.5 (B2.5) and 5 (B5) t ha−1 of biochar]; and two AM fungi inoculations [inoculated (AM+) and no-inoculated (AM-) plants]. All treatments were replicated three times. Before plowing, biochar (B2.5 and B5) was uniformly distributed on the soil surface to incorporate in the soil profile, while AM fungi (AM+) were distributed in the furrow of sunflower rows before sowing. Biochar and AM fungi were not applied in B0 and AM- treatments, respectively. Sunflower growth rate, pigments, photosynthesis rate and associated aspects, minerals content, antioxidant enzymes, abscisic acid, total phenolics and seed yield were measured. The results showed that growth parameters, radiation use efficiency, leaf pigments and seed yield decreased under irrigation regimes (NDI > MDI > SDI), while malondialdehyde (MDA) and hydrogen peroxide (H2O2) showed opposite trends. The combination AM fungi and biochar enhanced antioxidant enzymes activities, osmoprotectants, nutrient content and relative water content resulting in a significant decrease in oxidative damage in the drought stressed plants. Seed yield ranged from 4.95 to 1.78 t ha−1 and it was increased by the biochar application (+9% and +7% in B2.5 and B5, respectively) and AM fungi inoculation (+21 % in AM+) in all irrigation regimes. Overall, the plant's performance observed in the MDI-B5-AM+ was similar to that in NDI-B0-AM- indicating that AM fungi and biochar allow a reduction of water irrigation while maintaining crop yield. According to results, the combination of AM fungi and biochar rate should be adopted as a water-saving practice for sustainable production of sunflower cultivated in semi-arid environments, even if further studies should be carried out to evaluate their effects on other crops and environments
PRIMI RISULTATI DELLA RICERCA AGRONOMICA SULLA COLTIVAZIONE DELLA CANAPA INDUSTRIALE (CANNABIS SATIVA L.) NELL’ALTO LAZIO
No full textIl rinnovato interesse riguardo la coltivazione della canapa industriale (Cannabis sativa L.) è prevalentemente dovuto alle sue numerose utilizzazioni nell’industria tessile, farmaceutica, cosmetica, alimentare e nella bioedilizia. Tuttavia, dopo un trentennio di “non coltivazione” nel nostro Paese sono scomparse le cultivars tradizionali e deve di nuovo essere individuata la tecnica colturale anche alla luce delle nuove esigenze ambientali. Pertanto, la sua reintroduzione nell’agricoltura italiana richiede grande attenzione al fine di evitare l’impiego di semente non adatta e scelte agronomiche sbagliate. L’ambiente dell’Alto Lazio, grazie alle sue condizioni pedo-climatiche favorevoli, è storicamente vocato alla coltivazione della canapa la quale può rappresentare una valida coltura da rinnovo da inserire nei sistemi cerealicoli. Il presente lavoro riporta i risultati di alcune prove sperimentali realizzate nell’Alto Lazio (Tolfa, Viterbo e Allumiere) nel periodo 2007 – 2016, con lo scopo di fornire indicazioni utili sia sulla scelta delle cultivars di canapa più idonee, sia riguardo alcuni aspetti della tecnica colturale come la fertilizzazione azotata e la densità di semina. A tal fine sono state valutate alcune caratteristiche morfologiche e produttive quali l’altezza e il diametro basale della pianta, la produzione di steli e di seme. I risultati produttivi hanno evidenziato che nell’ambiente litoraneo (località Tolfa e Allumiere), caratterizzato da temperature elevate e una scarsa piovosità nel periodo marzo - settembre, la produzione di steli è risultata modesta con le cvs. Red Petiole e Ferimon che hanno fornito i migliori risultati. In questo ambiente sembra pertanto opportuno supportare la coltivazione della canapa con l’irrigazione. Nell’ambiente più interno (località Viterbo), tendenzialmente più piovoso durante il ciclo colturale della canapa, le produzioni di steli sono risultate più alte, soprattutto con le cvs. caratterizzate da fioritura media (Epsilon, Futura 75 e Santhica 27). Per quanto riguarda la produzione di seme, le cvs. caratterizzate da fioritura precoce (Ferimon, Fedora 17, Felina 32 e Uso 31) hanno fornito i migliori risultati. Per quanto riguarda l’efficacia della concimazione azotata, non ha evidenziato effetti significativi nell’ambiente litoraneo più siccitoso, mentre in condizioni di maggiore disponibilità idrica, come quelle rilevate nella località di Viterbo, la somministrazione di concime azotato ha determinato un effetto positivo sia sulle rese di steli sia su quelle di seme. Ulteriori ricerche si rendono comunque necessarie al fine di valutare un numero più ampio di genotipi di canapa e di individuare le tecniche colturali più idonee per le differenti tipologie di produzioni
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
Meta-Analysis Approach to Assess the Effects of Soil Tillage and Fertilization Source under Different Cropping Systems
No full textCrop yield under reduced tillage (RT) practices is a concern for sustainable production worldwide because it is related to different environmental and agronomic factors than conventionally tilled soils. This study aimed to evaluate how climate, soil, and farming practices could affect crop yield under RT, especially under different sources of fertilisation [mineral (M), mineral + organic (MO), and organic (O)]. Multilevel meta-analysis was adopted. The analysis was performed taking into consideration environmental conditions, soil properties, crop rotation, and crop species. Only studies that reported the interaction effect of soil tillage and nutrients management on grain yield were included. The results suggest that the impact of soil tillage and fertilisation sources on crop yield depended on crop species. Using reduced tillage practices, adopting only organic nutrient sources could produce enough grains for legume crops. However, combining both inorganic and organic fertilizers added benefits for cereal crops in terms of grain yield production. This study highlights how conservation tillage practices could be affected by environmental and agronomic factors
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
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