96 research outputs found
Screening of plant extracts for antifungal activities against Colletotrichum species of common bean (Phaseolus vulgaris L.) and cowpea (Vigna unguiculata (L.) Walp)
No full textThe aim of the present investigation was to evaluate the antifungal activities of plant extracts which can be used to
control bean and cowpea anthracnose. Acetone, ethyl acetate and water extracts of Ipomoea batatas, Carica
papaya, Allium sativum, Syzygium cordatum, Chlorophytum comosum and Agapanthus caulescens were
screened in vitro for their antifungal activities against Colletotrichum lindemuthianum and Colletotrichum
dematium of common bean and cowpea using the agar disc infusion and microtitre double-dilution techniques.
The same extracts were then tested for antifungal activity in vivo as seed treatments against anthracnose disease.
The water extracts of Carica and Syzygium were active against C. lindemuthianum and had minimum inhibitory
concentrations (MICs) of 1·56 mg/ml. Syzygium, Allium and Chlorophytum water extracts were active against
C. dematium and MICs were 3·13, 6·25 and 12·5 mg/ml, respectively. The MICs of Allium, Syzygium and
Agapanthus acetone extracts were 0·78, 3·13 and 6·25 mg/ml, respectively, against C. lindemuthianum and 0·78,
6·25 and 3·13 mg/ml against C. dematium. Agapanthus water extracts and all the acetone extracts tested in vivo
effectively reduced the incidence and severity of bean anthracnose disease in the greenhouse. Agapanthus
acetone, Allium water, and both acetone and water extracts of Carica and Syzygium performed well in vivo in
reducing cowpea anthracnose disease and compared well with reductions due to the application of the synthetic
fungicide fludioxonil+mefenoxam (the commercial product Celest® XL) applied at 25 gai/l and also with levels
in the non-inoculated control. The Agapanthus, Carica, Syzygium and Allium extracts were active on both
Colletotrichum spp. in vitro and also reduced anthracnose disease of bean and cowpea and are potential seed
treatments in anthracnose disease control. The easy seed treatment process and the accessibility of plants used in
the present study could lead to high adoption of the use of the plant extracts as seed treatments by resource-poor,
smallholder farmers.http://journals.cambridge.org/action/displayJournal?jid=AGSam201
The effect of traditional storage methods on germination and vigour of maize (Zea mays L.) from northern KwaZulu-Natal and southern Mozambique
No full textIn Sub-Saharan Africa, maize (Zea mays L.) is one of the most nutritional crops and proper storage of seeds continues to be a challenge for subsistence farmers. Storage fungi, which reduce seed quality, become active in seeds when moisture levels are 14% or higher and this is influenced by the way seeds are stored. The aim of the present study was to test germination and vigour of maize seeds that were subjected to traditional storage during 2005 and to test germination of the maize seeds after storage for one year under conditions of fluctuating temperature. A preliminary survey was conducted and maize samples (white and yellow) were collected from small-scale subsistence farmers in northern KwaZulu-Natal (South Africa) and Mozambique. Seeds that were left in the field to dry and seeds that were commercially treated with Celest® XL served as controls. Germination was measured according to the International Seed Testing Association (ISTA) rules. The maize that was left in the field (NHS) to dry gave 100% germination in 2005. The treated control had a germination of 94.0%. Seeds that were imbibed for 40 h had the highest percentage weight increase following rapid imbibition but four of the six samples maintained germination above 70% following slow imbibition. The conductivity of the solute was read following imbibition. Field stored maize had the lowest solute leakage (1181 μS) and this correlated with the high percentage seeds with living tissue as indicated by the tetrazolium staining following rapid (94.4%) and slow (95.8%) imbibition. The number of fungi isolated from the samples reflected the initial condition of the samples with the fungicide treated control having the lowest percentage infection (11%), NHS had 33% and yellow maize that was stored on the cob and had with insect damage (SIH) had the highest, namely 71%. After the first set of experiments, samples were stored at 26–28 °C to simulate the fluctuating original storage conditions. A year later the samples were subjected to the standard germination test. The decline in seed viability during the storage period was exhibited by results of the standard germination test. Maize that was left in the field had a 74.7% decrease in germination while the sample stored in potato bag (PHEL) and the treated control maintained germination above 80%. Two of the six samples failed to germinate. This study also showed that fungicide seed treatment is a viable option to maintain viability of the seeds, especially when the maize is to be stored until the next season
L'anxiété de séparation et les relations d'attachement : théories, connaissances empiriques et interventions psychosociales.
No full textCurieusement, les troubles intériorisés ont été nettement moins étudiés que les problèmes d'externalisation, mais la recherche sur les troubles anxieux suggère néanmoins que la présence de ces phénomènes à la période scolaire constitue un facteur de risque menant au développement de certaines difficultés psychosociales et des formes de psychopathologie durant l'enfance ou l'adolescence (Dadds et al., 1996). Parmi les troubles anxieux retrouvés à l'enfance, ce travail abordera le trouble d'anxiété de séparation (TAS), principalement caractérisé par une perturbation des interactions entre l'enfant et ses figures principales d'attachement. Étant donné la nature relationnelle de ce trouble, une perspective transactionnelle sera privilégiée afin de mieux comprendre le processus impliqué dans le développement du T.A.S. Le modèle de Manassis et Bradley (1994) fût une source d'inspiration pour la présente étude puisqu'il met l'emphase sur la théorie de l'attachement pour expliquer l'appartition de troubles anxieux. En s'inspirant de ce modèle, une recension des écrits portera principalement sur l'influence des relations d'attachement parent-enfant et leurs implications dans le développement du TAS. Comme la majorité des recherches portent sur l'ensemble des troubles anxieux, il est difficile d'isoler les facteurs de risque associés aux relations parent-enfant spécifiques pour le TAS. Cette étude tentera donc d'expliquer en quoi certaines recherches peuvent nous éclairer plus particulièrement sur les origines et le processus de développement du TAS. Du point de vue de l'intervention, il s'agit de connaître les facteurs de risque qui président le développement du TAS afin de poser les bases d'interventions préventives et curatives efficaces auprès de cette population. L'objectif de ce travail est également de soumettre des programmes jugés efficaces dans le domaine à une évaluation critique et d'y apporter des recommendations
Viability and vigour of farm-saved dry bean (Phaseolus vulgaris L.) seed of subsistence farmers in KwaZulu-Natal, South Africa
No full textControl of Alternaria leaf spot of coriander in organic farming
No full textIncreased consumer awareness on the means of production of food in recent decades has intensified pressure for growth of organic farming particularly for its benefit on the environment due to minimal use of synthetic chemicals. In this regard, non-chemical seed treatments, viz. biocontrol agents (Trichoderma and Bacillus), hot water treatments and plant extracts, were studied as alternatives to synthetic chemicals for the management of Alternaria alternata (Fr.) Keissl. causing Alternaria leaf spot affecting organically produced coriander (Coriandrum sativum L.). Antifungal activities of acetone, ethyl acetate and water extracts of Allium sativum, Carica papaya, Datura stramonium, Lantana camara, Tagetes minuta and Zingiber officinale were evaluated using the disc diffusion assay. Discs impregnated with acetone extracts of Allium, Datura and Zingiber at a concentration of 15 mg/mL completely inhibited growth of A. alternata, whereas discs impregnated with Tagetes recorded the lowest antifungal activity. Ethyl acetate extracts of all plants except Carica and Tagetes at 15 mg/mL showed antifungal activity which was comparable to Celest® XL, a synthetic fungicide. A comparison of water extracts showed that discs impregnated with Lantana extract at 15 mg/mL had the highest zones of inhibition (16.5 mm); however, discs impregnated with Tagetes at a concentration of 5 mg/mL yielded the lowest antifungal activity against A. alternata (0.3 mm). The greenhouse trial showed that all non-chemical seed treatments significantly improved percentage seedling emergence, except for seeds treated with Lantana extracts and hot water at 48 °C for 60 min, when compared to untreated controls. The study showed that seeds treated with Trichoderma sp. yielded seedlings with the longest shoots, which were significantly higher than seedlings grown from seeds treated with Celest® XL. There was no incidence of Alternaria leaf spot disease on seedlings from seeds treated with Bacillus sp. and an extract of Allium, which compared well with seeds treated with Celest® XL. Since there are limited chemicals registered for management of diseases affecting herb production, the results of this study have shown that soaking coriander seeds in a hot water bath set at 54 °C for 15 mins, and biocontrol agents (Trichoderma and Bacillus) and extracts of Allium and Zingiber are potential replacements of synthetic fungicides in controlling Alternaria leaf spot disease on coriander produced under organic farming.The European Union’s Seventh Framework Programme (KBBE.2012.1.2–05: 311875) TESTA (Seed health: Development of seed treatment methods, evidence for seed transmission and assessment of seed health).https://link.springer.com/journal/106582020-02-09hj2019Forestry and Agricultural Biotechnology Institute (FABI)Plant Production and Soil Scienc
Evaluation of mefenoxam and fludioxonil for control of Rhizoctonia solani, Pythium ultimum and Fusarium solani on cowpea
No full textCowpea (Vigna unguiculata) is susceptible to pathogens such as Rhizoctonia solani Pythium ultimum and Fusarium solani causing seedling diseases in cowpea, resulting in low yields. Three commercial synthetic fungicides containing mefenoxam 350 g ai L-1 mefenoxam 240 g ai L-1 and fludioxonil 100 g ai L-1, respectively, were evaluated against these pathogens on cowpea in the greenhouse following promising in vitro results. The fungicides were applied initially as a soil drench to seedling trays at planting and fortnightly as a drench according to manufacturer’s recommendations. All fungicides, except mefenoxam 350 g ai L-1 in one trial, were able to reduce diseases caused by R. solani. With the exception of mefenoxam 350 g ai L-1 in F. solani all fungicides increased seedling emergence and dry shoot and root mass of plants and all fungicide treatments reduced disease of seedlings grown in F. solani and P. ultimum inoculated growth medium. Although all three fungicides reduced the percentage of diseased seedlings, none of them gave complete control of the diseases caused by the three pathogens under the trial conditions.National Research Foundation.http://www.tandfonline.com/loi/tjps202017-06-07hb2016Plant Production and Soil Scienc
FIELD TOLERANCE OF SELECTED VARIETIES TO AND FUNGICIDE EFFICACY AGAINST ALTERNARIA BLIGHT OF SWEET POTATO
No full textAlternaria blight (AB) of sweet potato ( Ipomoea batatas L. ), caused
by Alternaria spp., was recently reported in South Africa, but is
common in southern and eastern Africa. Elsewhere in the world, AB is
controlled primarily using resistant varieties. Twenty-five sweet
potato varieties/breeding lines, from different origins were assessed
for tolerance to AB. The materials were planted in fields having a
history of AB disease and rated for tolerance based on a General
Disease Index (GDI), with the lowest scores representing tolerance, and
the higher scores representing susceptibility. Variety 199062-1 had the
lowest GDI value, and was the most tolerant to AB; while W119 had the
highest GDI value and was the most susceptible to the disease. Other
varieties/breeding lines showed a variation in GDI values between most
tolerant and most susceptible. Among the fungicides tested under field
conditions, the mixture azoxystrobin-difenoconazole was the most
effective in reducing AB intensity. Fungicides pyraclostrobin-boscalid,
unizeb, azoxystrobin-chlorothalonil and cymoxanil-mancozeb were also
effective against the disease.L\u2019alternariose (AB) de la patate douce ( Ipomoea batatas L. ),
maladie caus\ue9e par Alternaria spp., est une maladie nouvellement
rencontr\ue9e en Afrique du Sud, mais tr\ue8s fr\ue9quemment
rencontr\ue9e dans les pays au Sud et \ue0 l\u2019Est de
l\u2019Afrique. Ailleurs dans le monde, l\u2019utilisation de
vari\ue9t\ue9 r\ue9sistantes est la premi\ue8re mesure de lutte
contre les d\ue9g\ue2ts caus\ue9s par AB. Vingt cinq
vari\ue9t\ue9s de patate douce de diverses origines ont
\ue9t\ue9 \ue9valu\ue9es pour leur sensibilit\ue9 \ue0
l\u2019alternariose. Le mat\ue9riel g\ue9n\ue9tique avait
\ue9t\ue9 plant\ue9 dans des champs ayant une fois infect\ue9s
de AB et class\ue9s tol\ue9rants en fonction de leur index
g\ue9n\ue9ral de la maladie (GDI). Les plus petits scores indiquent
la tolerance, tandis que les scores les plus \ue9lev\ue9s indiquent
la susceptibilit\ue9. La vari\ue9t\ue9 199062-1 avait la plus
petite de GDI et donc \ue9tait le plus tolerant \ue0 AB, tandis que
la vari\ue9t\ue9 W119 pr\ue9sentait la valeur de GDI la plus
\ue9lev\ue9e; par cons\ue9quent \ue9tait la plus susceptible de
toutes les vari\ue9t\ue9s. Les autres vari\ue9t\ue9s
\ue9taient diff\ue9rentes en ce qui concerne leur GDI, les valeurs
de GDI variaient du plus petit au plus grand. Parmi les fongicides
test\ue9s, le m\ue9lange azoxystrobin-difenoconazole \ue9tait le
plus efficace. Les fongicides pyraclostrobin-boscalid, unizeb,
azoxystrobin-chlorothalonil et cymoxanil-mancozeb \ue9taient aussi
efficace contre l\u2019 alternariose
How Sudden stratospheric warmings affect the whole atmosphere
No full textOpen Access. Text © 2018. The authors. CC BY 3.0
Except where otherwise noted, images are subject to copyright. Any reuse without express permission from the copyright owner is prohibited.Ideas for this article were developed during international team meetings supported by the International Space Science Institute (ISSI; Bern, Switzerland). The National Center for Atmospheric Research is supported by the U.S. National Science Foundation. J.L.C., C.S., and T.A.S. are partly supported by the German Research Foundation’s Priority Program 1788 “DynamicEarth.” L.P.G. is supported by NASA through LWS grant NNX13AI62G and by U.S. NSF grant AGS-1343056. H.S. is partly supported by the German Research Foundation (DFG) under FOR 1898 (MS-GWaves), project SCHM 2158/5-1 (GWING). V.L.H. is supported by U.S. NSF AGS-1343031, NASA LWS NNX14AH54G, and NASA HGI NNX17AB80G. B.F. is supported by the Spanish MCINN under grant ESP2014-54362-P and EC FEDER funds
Clinical outcome of protein-energy malnourished patients in a Brazilian university hospital
No full textMulti-phonon vibrations at high angular momentum in <sup>182</sup>Os
No full textExperimental Nuclear Structure Udgivelsesdato: 30 Oct
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