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Resistance to graminicides in monocotyledons weeds Case studies of Lolium spp. and Phalaris paradoxa in Italy
Full text linkHerbicide resistance is evolving fast in Italy, especially in cropping systems characterised by low diversity in space and time. In these systems there is often no rotation of herbicides mode of action (i.e. durum wheat and rice monoculture). Resistance is also evolving faster in cross-pollinating and genetically variable species (i.e. Lolium spp.). In Italy about 100,000 ha have been estimated to suffer resistant problems, mainly in durum wheat (Lolium spp., Avena sterilis and Papaver rhoeas) and paddy rice (mostly Schoenoplectus mucronatus and Cyperus difformis).
ACCase is an essential enzyme in fatty acid biosynthesis in eukaryotes and prokaryotes. In plants, two forms of ACCase have been identified - the first is located in the chloroplast, the primary site of plant fatty acid biosynthesis, and the second in the cytosol. The homomeric ACCase in the cytosol of nearly all plant species and the heteromeric ACCase in the chloroplasts of dicots are insensitive to APP, CHD and DEN herbicides. In contrast, the plastidic homomeric ACCase in nearly all grass species is herbicide-sensitive, and this is the basis for selective control of grass-weeds by ACCase herbicides.
The aims of the research were: (1) to monitor throughout the country the situation of resistance to Acetyl-CoA Carboxylase (ACCase) in Lolium and Phalaris species following complaints to the agrochemical industries; (2) to develop a reliable Petri dish quick test to detect ACCase-inhibitors resistance in Lolium and Phalaris species; (3) to characterise clethodim and pinoxaden resistance in Lolium spp. using different experimental approaches; (4) agronomic and molecular characterisation of a few populations of P. paradoxa resistant to ACCase inhibitors.
Through classic pot screenings, populations with different patterns and levels of resistance have been selected to be studied with different approaches: outdoor dose-response, at molecular level using molecular markers and sequencing and at physiological level through enzyme bioassay. As pot experiments are costly and time consuming, a rapid test in Petri dishes based on survival data has been developed for detecting resistance to ACCase-inhibitors.
Screening results revealed that among 41 tested Lolium populations, 23 were resistant to clodinafop, 19 to sethoxydim and 15 to pinoxaden. Among the 17 P. paradoxa populations, 3 were resistant to clodinafop, and one to sethoxydim and pinoxaden. Resistance to pinoxaden is associated to a wide pattern of cross-resistance among ACCase-inhibitors.
The Petri dish seed quick test has been developed in order to find a discriminating herbicide concentration between susceptible and resistant populations; a herbicide concentration ("comparing dose") that gives results comparable to the recommended field dose used in greenhouse pot experiments; and a concentration discriminating between strong and weak resistance. The "comparing doses" has been validated using other populations not included in the set up experiments. The "comparing dose" for Lolium spp. have been: clodinafop 1 ?M, pinoxaden 0.2 ?M, clethodim 0.2 ?M and sethoxydim 0.1 ?M; for P. paradoxa, clodinafop 0.1 ?M, pinoxaden 0.05 ?M and clethodim 0.1 ?M. The Petri dish seed quick test revealed to be reliable with the two species in screening large numbers of samples compared with the costly and time consuming pot experiment. The quick test improves ACCase-resistance detection and can be adopted as a routine facility.
Molecular investigation identified five ACCase mutations (Ile1781Leu, Trp2027Cys, Ile2041Asn, Asp2078Gly and Cys2088Arg) and revealed 12 genotypes in 14 clethodim resistant Lolium populations. Pinoxaden resistance has been reported associated to Lolium population mutants for five ACCase mutations (Ile1781Leu, Ile2041Val/Asn, Asp2078Gly, Cys2088Arg and Gly2096Ala) with specific homozygous and heterozygous status among mutations. In P. paradoxa two mutations have been associated to pinoxaden resistance: Ile1781Val and Asp2078Gly, always recognised at the homozygous status.
The research has established that resistance to ACCase herbicides depends on the specific resistant allele(s), on the homo/heterozygous status of plants for the specific resistant allele(s), and on the combinations of different resistant alleles, as well as herbicide rates. To understand and devise resistance management strategies, knowledge of all these factors coupled with field records of herbicide and agronomic techniques used is essential.
The overall situation of grass resistance in Italian durum wheat crops indicates that there is no single chemical that can solve all resistance problems. Therefore all stakeholders should be aware that IWM (or better ICM) is needed to properly manage resistance in the field.
It must also be clear that IWM or ICM requires a higher technological level coupled with a deeper knowledge of all components of the cropping system
Barnyardgrass shows sensitivity to reduced doses of topramezone at different growth stages
Full text linkUsing less than the labelled dose of herbicides depends mostly on weed spectrum and growth stage of target weeds. The aim of the greenhouse experiment was to determine the efficacy of recommended (67.2 g a.i. ha-1) and reduced doses (44.8, 33.6, 22.4, 16.8 and 8.4 g a.i. ha-1) of topramezone combined with adjuvants (NIS and MSO) on barnyardgrass (Echinochloa crus-galli [L.] P. Beauv.) at two different growth stages: BBCH 13 and BBCH 21–22. The results showed unsatisfactory efficacy of topramezone applied alone at the recommended dose on both growth stages (>50%). When applied with adjuvants (MSO or NIS) at BBCH 13, topramezone 100% visually damaged barnyardgrass and reduced biomass >90%, at each applied dose. In contrast, at BBCH 21–22 only topramezone double dose achieved 73% visual damage. Reduced topramezone doses applied with adjuvants gave insufficient barnyardgrass control at tillering stage (< 40%). Results indicate the possibility of reducing the topramezone dose to more than 87% by adding adjuvants (MSO or NIS) but only when applied at early growth stage of barnyardgrass (BBCH 13). At BBCH 21–22 satisfactory barnyardgrass control cannot be achieved by using topramezone either alone or with adjuvants
Housekricket Smallscale Farming
No full textThe potential nutritional value of insects in general and the common house
cricket, Acheta domesticus, in particular in human diets has long been recognized.
In addition to providing a rich source of high quality proteins for human consumption,
crickets and other related insects such as grasshoppers and locusts
offer several other advantages as human food sources: they have a short life
span, produce numerous offspring, are amenable to human cultivation, and can
flourish under a wide range of environmental conditions. The main aims of this
study were two: compare the yield of crickets raised on four different diets, and
determine the amino acid, fatty acid, and mineral and trace element content of
crickets grown under the best of these diets. The four diets were: aromatic-arboreal
(AAD), dairy cow diet (DCD), DCD supplemented with yeast, and human
refuse diet (HRD). The greatest yield (0.45 g per 10 g of feed) and highest survival
(47.5%) of A. domesticus was achieved with HRD when grown for 9 weeks
in 24 hours daylight. The protein content of crickets raised on all four diets ranged
from 56.2 to 60.0% dry weight, and in all cases the essential amino acid score of
the proteins approximated or exceeded the World Health Organization protein
standard. The crickets contained 63–122 mg fatty acid per g dry weight, most of
which was accounted for by palmitic acid, oleic acid, and the two fatty acids
essential for humans, namely linoleic acid and a-linolenic acid. Crickets grown
on any one of the diets contained significant quantities of the following minerals
or trace elements: calcium (366–480 μg per g dry weight), copper (8.5–9.2 μg
per g), iron (16.2–26.7 μg per g), and magnesium (255–306 μg per g). These data support the contention that crickets contain quantities of many nutrients that
are essential to humans and show that the insect represents a commercially feasible
source of food for human populations
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
spp.) field populations
No full textHerbicides inhibiting the synthesis of very long-chain fatty acids (HRAC group K3 , WSSA group 15), such as flufenacet, play an important role in weed management strategies, particularly when herbicide resistance to inhibitors with other modes of action, such as acetolactate synthase or acetyl coenzyme A carboxylase (ACCase), has already evolved. So far, only a few cases of resistance towards inhibitors of the synthesis of very long-chain fatty acids have been described. In this study, we characterized the level of flufenacet resistance in several Lolium spp. field populations and investigated the resistance mechanism
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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