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The five song cycles for voice and piano by Benjamin Britten written specifically for Peter Pears the effect of their relationship /Strauss, Robert, January 1900 (has links)
Thesis (D.M.A.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xvii, 288 p. : music. Vita. Includes abstract. Includes bibliographical references (p. 229-281). Includes discography: p. 282.
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The ecology and morphological variation of Opuntia (Cactaceae) species in the mid-south, United StatesMajure, Lucas C., January 2007 (has links)
Thesis (M.S.)--Mississippi State University. Department of Biological Sciences. / Title from title screen. Includes bibliographical references.
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Physical, sensory and consumer analysis of pear genotypes among South African consumers and preference of appearance among European consumersManning, Nicola 03 1900 (has links)
Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2009. / The aim of this research project was to determine the preference of pear appearance and taste
among South African pear consumers using descriptive sensory analysis, consumer
preference and physical maturity measurements. The preference of external pear appearance
among European consumers was also established. The Agricultural Research Council (ARC)
Infruitec-Nietvoorbij, South Africa, aims to breed new cultivars with a local as well as export
market potential. They are focused on a range of blushed cultivars from early to late season
which do not loose their skin colour. Important eating quality characteristics they are focused
on are high sugar content (sweet taste) and a strong pear flavour. Both research studies
performed on local South African consumers showed that these objectives align very well
with consumer preference. Lightly coloured blushed pears were preferred and important
sensory attributes were pear flavour, sweet taste, melt character, juiciness and a soft texture.
Sour taste, astringency, mealiness and grittiness were negative attributes. The appearance
preference conducted on European consumers determined that these consumers prefer a bright
yellow or green colour with a light red or pink blush. Shape played a role and a typical pear
shape was preferred. The outcomes of the research performed on local South African
consumers were compared to results found internationally. The findings were consistent with
important sensory attributes being pear flavour, sweetness and juiciness and yellow or green
colours preferred or a light blush was also acceptable. Age and gender did not seem to play a
role in the preference analyses. Therefore, preference studies can be conducted locally on
new cultivars for the export market. Blushed cultivars are prone to red colour loss in high
temperature conditions. Breeding of selections (e.g. ‘Cheeky’) that accumulate more red
pigment and are therefore less prone to colour loss has been done to try to overcome this
problem. However, these selections are redder and darker in colour and have a lower
preference among consumers. A possible solution to this could be to breed light blushed
pears (e.g. Rosemarie) but to market the cultivar, as is the case with Cripp’s Pink apples, with
separate trademark names for fruit with adequate and inadequate blush development.
Thereby, the producers will still receive compensation for their produce if the colour is lost
but if not, a higher premium will be received.
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Effect of canopy position on fruit quality and consumer preference for the appearance and taste of pearsCronje, Arina 04 1900 (has links)
Thesis (MScFoodSc) Stellenbosch University, 2014 / ENGLISH ABSTRACT: We aimed to determine how canopy position influences fruit quality and consumer preference for
the eating quality and appearance of ‘Forelle’, ‘Bon Chrétien’ and ‘Bon Rouge’ pears. Our
hypothesis was that consumer preference would be higher for the appearance and eating quality of
outer canopy fruit.
Our first trial investigated the effect of canopy position and cold storage duration on quality
attributes and consumer preference for ‘Forelle’ pears. Mealiness was much more prevalent in
outer canopy fruit in 2012 and after 9 and 12 weeks cold storage in 2011. In 2011, consumers
preferred the eating quality of inner canopy pears that had been subjected to 12 and 16 weeks of
cold storage while inner canopy pears were generally preferred in 2012. This study provides
support for the mandatory 12 weeks cold storage of ‘Forelle’ pears.
Our second trial investigated the effect of canopy position and harvest maturity within the
commercial picking window on the quality attributes and consumer preferences for ‘Forelle’ pears.
Inner canopy pears of harvest 1 (23 February) and harvest 2 (27 February) were significantly
preferred in terms of eating quality. The general dislike for harvest 3 (13 March) pears and outer
canopy fruit seemed to relate to an incidence of mealiness. Our results suggest that harvesting
‘Forelle’ pears at a firmness ≈6.2 kg will ensure that both inner and outer canopy pears have
acceptable eating quality.
In our third trial, fruit were harvested at commercial firmness from two orchards in each of Elgin
and Ceres to assess the effect of orchard site on quality attributes of ‘Forelle’ pears. Total soluble
solids (TSS) were higher in Elgin while flavour attributes were more pronounced in Ceres. In both
areas, outer canopy pears were higher in TSS and lower in titratable acidity (TA) but canopy
position had no effect on sweet and sour taste. Mealiness incidence was high in outer canopy fruit
from Elgin, as well as in one Ceres orchard. Further research over consecutive seasons is needed
to determine the reasons for orchard differences in mealiness incidence.
Our fourth trial investigated the effect of canopy position on quality attributes and consumer
preference for ‘Bon Chrétien’ and ‘Bon Rouge’ pears. Despite a higher TSS:TA ratio in outer
canopy ‘Bon Rouge’ pears and a higher TSS and dry matter concentration in outer canopy ‘Bon
Chrétien’ pears, canopy position did not affect sensory eating quality attributes. Seen overall,
results indicate that canopy position has a minor effect on consumer preference for ‘Bon Chrétien’
and ‘Bon Rouge’ eating quality.
No significant differences in colour and consumer preference for appearance were found between
outer and inner canopy ‘Bon Chrétien’ pears. Consumers slightly preferred the redder outer
canopy ‘Bon Rouge’ pears over the less red inner canopy fruit. Although consumers preferred the
red blush colour of outer canopy ‘Forelle’ pears, inner canopy pears also received high scores.
Inner canopy ‘Forelle’ pears should not be viewed as inferior to outer canopy fruit with regard to
both eating quality and appearance. / AFRIKAANSE OPSOMMING: Ons het gepoog om die effek van boomposisie op vrugkwaliteit en verbruikersvoorkeur vir die eetkwaliteit en voorkoms van ‘Forelle’, ‘Bon Chrétien’ en ‘Bon Rouge’ pere te ondersoek. Ons hipotese was dat verbruikersvoorkeur hoër sou wees vir die voorkoms en eetkwaliteit van pere van die buitekant van die boom se blaredak.
Ons eerste proef se doelstelling was om die effek van boomposisie en koelopberging op die kwaliteitseienskappe en verbruikersvoorkeur vir ‘Forelle’ pere te bepaal. Melerigheid was beduidend meer aanwesig in buitevrugte in 2012 asook na 9 en 12 weke koelopberging in 2011. Verbruikersvoorkeur vir eetkwaliteit was die hoogste vir binnevrugte na 12 en 16 weke koelopberging in 2011 terwyl binnevrugte in die algemeen voorkeur geniet het in 2012. Hierdie studie steun die bevindinge van vorige studies dat ‘Forelle’ pere vir ten minste 12 weke koelopgeberg moet word.
Die doel van ons tweede proef was om te bepaal of ‘Forelle’ pere wat by verskillende ryphede binne die kommersiële oesperiode geoes is, verskille toon in kwaliteitseienskappe en of hierdie verskille, indien enige, verband hou met verbruikersvoorkeur vir eetkwaliteit. Die eetkwaliteit van binnevrugte van oes 1 (23 Februarie) en oes 2 (27 Februarie) is verkies bo buitevrugte. Die algemene afkeur vir oes 3 (13 Maart) en buitevrugte kan moontlik toegeskryf word aan die hoë voorkoms van melerigheid. Ons resultate dui aan dat beide binne- en buitevrugte aanvaarbare eetkwaliteit behoort te hê indien ‘Forelle’ pere by ‘n fermheid van ≈6.2 kg geoes word.
Vir ons derde proef is ‘Forelle’ pere geoes by kommersiële fermheid (≈6.4 kg) vanaf twee boorde in elk van Elgin en Ceres. Totale opgeloste vastestowwe (TOV) was hoër in Elgin pere terwyl geur-eienskappe meer prominent was in Ceres pere. In beide areas het buitevrugte hoër TSS en laer titreerbare sure (TS) gehad, maar boomposisie het egter geen effek op soet en suur smaak gehad nie. Die voorkoms van melerigheid was hoog in buitevrugte van die Elgin boorde, sowel as in een van die Ceres boorde. Verdere navorsing oor opeenvolgende seisoene word benodig om redes vir die verskille in die voorkoms van melerigheid tussen boorde te ondersoek.
Die doelstelling van ons vierde proef was om die effek van boomposisie op die kwaliteitseienskappe en verbruikersvoorkeur vir ‘Bon Chrétien’ en ‘Bon Rouge’ pere te ondersoek. Ondanks ‘n hoër TOV:TS ratio in ‘Bon Rouge’ buitevrugte en ‘n hoër TOV en droë massa konsentrasie in ‘Bon Chrétien’ buitevrugte, het boomposisie ‘n minimale impak gehad op sensoriese eetkwaliteitseinskappe en verbruikervoorkeur vir die pere.
Boomposisie het geen effek op die kleur en verbruikersvoorkeur vir die voorkoms van ‘Bon Chrétien’ pere gehad nie. Verbruikers het ‘n effense hoër voorkeur getoon vir die rooier ‘Bon Rouge’ buitevrugte. Alhoewel verbruikers die aantreklike rooi bloskleur van ‘Forelle’ buitevrugte verkies het, het die groen tot geel binnevrugte ook hoë voorkeurpunte behaal. Rakende voorkoms en eetkwaliteit, is ‘Forelle’ binnevrugte glad nie minderwaardig teenoor buitevrugte nie.
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Chemical thinning of European pear cultivars (Pyrus communis L.)Chabikwa, Tinashe Gabriel 12 1900 (has links)
Thesis (MScAgric (Horticulture))--Stellenbosch University, 2008. / Chemical thinning of fruit trees has become a central management practice for ensuring high
fruit quality at harvest and return bloom the following season. Three trials were conducted in
the 2004/5, 2006/7 and 2007/8 seasons to investigate the efficacy and mode of action of
chemical thinning agents on European pear cultivars (Pyrus communis L) in the Western
Cape, South Africa.
The first trial was conducted in the 2004/5 and 2006/7 seasons to evaluate the efficacy of 50,
100 and 150 mg.l-1 6-benzyladenine (BA), and 30 and 40 mg.l-1 naphthylacetamide (NAD) on
‘Early Bon Chrétien’ pear. BA was more effective than NAD in reducing crop load and
improving fruit size. Crop load decreased and fruit size increased with increasing rate of BA.
BA significantly improved, whilst NAD failed to improve return bloom.
In the second trial, three experiments were conducted in the 2006/7 and 2007/8 seasons to
evaluate the efficacy of 100 to 200 mg.l-1 BA on ‘Forelle’ pear. The first experiment was
conducted in the 2006/7 season where BA rates of 100, 125 and 150 mg.l-1 generally failed to
reduce crop load or to improve fruit size and fruit size distribution and return bloom. The
second experiment was conducted in the 2007/8 season where two BA rates, 150 and 200
mg.l-1 and a split-application of 3 x 50 mg.l-1 improved fruit size. The 200 mg.l-1 rate was the
most effective treatment. BA did not improve fruit size distribution and return bloom. The
third experiment was conducted in the 2007/8 season where the effect of rate and timing of
BA applications was evaluated. Two rates, 150 and 200 mg.l-1 were applied 8, 11 and 17
days after full bloom (d.a.f.b.). There was no significant interaction between BA rate and
application time. The 200 mg.l-1 rate and the 11 d.a.f.b. (i.e. 8 to 10 mm average fruit size)
applications were more effective in reducing crop load, and improving fruit size. BA at 150
and 200 mg.l-1 and at all application times significantly improved return bloom relative to the
control.
From these trials we concluded that BA is a reliable thinner for ‘Early Bon Chrétien’ at rates
of 100 or 150 mg.l-1. On ‘Forelle’, BA is not a reliable thinner and we recommended further
trials with BA in combination with other thinning agents. In the third trial, three experiments were conducted in the 2007/8 season to investigate the
mode of action and effect of BA application time on European pear cultivars. The effect of
site of application, bourse shoot growth and fruit size at time of application on the efficacy of
BA was evaluated. Results from the experiments on the effect of site of application and
bourse shoot growth were inconclusive. In terms of fruit abscission, there was a significant
interaction between BA application time and fruitlet size. Early BA applications (8 d.a.f.b.)
were significantly more effective in promoting fruit abscission, than later (11 and 17 d.a.f.b.)
applications. Smaller fruit (6 to 8 mm) were found to be more susceptible to BA-induced
fruit abscission than bigger fruit (8 to 12 mm).
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O episódio do furto das peras no livro segundo das Confissões de Agostinho de Hipona: (Confissões II, IV-X, 9-18) / The episode of the theft of the pears on the second book of Confessions by Augustine of Hippo: (Confessions II, IV-X, 9-18)Rafael Alves de Sousa Barberino Rodrigues 06 September 2012 (has links)
Nas Confissões de Agostinho de Hipona, o episódio do furto das peras, localizado no livro segundo, é possivelmente um dos dois momentos mais importantes no percurso dos seus seis primeiros livros. No entanto, tem boa parte de seu potencial filosófico desprezado. Os comentários são numerosos, mas os melhores tratam-no do ponto de vista de sua composição. Já os trabalhos filosóficos sobre o episódio não têm nem a mesma frequência, nem o mesmo fôlego. O que é de se lamentar bastante, visto o potencial que o episódio tem de fazer pensar. A fim de mudar um pouco este cenário, o que se pretende com essa dissertação é uma leitura mais atenta deste episódio. Planeja-se, em dois capítulos, cumprir dois estudos a seu respeito. Um primeiro, e mais introdutório, visa reunir os resultados daqueles estudos literários sobre o episódio. Estes importam, na medida em que preparam a leitura mesma do texto. Seus símbolos não são simples de compreender, e, além do mais, dão o que pensar. O segundo capítulo se dedica ao estudo filosófico do ato imoral, tal como ele se apresenta no feito no episódio. Por fim, para, entre outras razões, se solucionar algumas dificuldades de ordem teórica que aparecem na leitura do episódio, o terceiro capítulo pretende pensar o episódio dentro da estrutura confessional que o sustenta. Ver-seá que o livro segundo é um ótimo laboratório para o estudo do conceito de confissão em Agostinho. / In the Confessions of Augustine of Hippo, the episode of the theft of pears, located on the second book, is possibly one of the two most important moments in the course of its first six books. However, most of its philosophical potential is ignored. There are numerous comments, but the most elaborated ones deal with it from the point of view of its composition. The philosophical works on the episode are not as numerous and are not as extensive. Which is unfortunate, because of the potential that the episode has to induce to deeper thinking. In order to change a little this scenario, this thesis has been developed to propose a more attentive reading of this episode. It has been planned to introduce two studies, in two chapters. A first, and more introductory, aims to bring together the results of those literary studies about the episode. They are important to prepare the reader, so that they will be able to truly understand te text. Its symbols are not something simple to understand, and, moreover, they require deeper thinking. The second chapter is dedicated to the study of philosophical immoral act, the way it happens in the episode.
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A needs assessment for a minor eye condition service within Leeds, Bradford and Airedale, UKSwystun, Alexander G., Davey, Christopher J. 03 October 2019 (has links)
Yes / Background: There are a number of limitations to the present primary eye care system in the UK. Patients with
minor eye conditions typically either have to present to their local hospital or GP, or face a charge when visiting
eye care professionals (optometrists). Some areas of the UK have commissioned enhanced community services to
alleviate this problem; however, many areas have not. The present study is a needs assessment of three areas
(Leeds, Airedale and Bradford) without a Minor Eye Conditions Service (MECS), with the aim of determining whether
such a service is clinically or economically viable.
Method: A pro forma was developed for optometrists and practice staff to complete when a patient presented whose
reason for attending was due to symptoms indicative of a problem that could not be optically corrected. This form
captured the reason for visit, whether the patient was seen, the consultation funding, the outcome and where the
patient would have presented to if the optometrists could not have seen them. Optometrists were invited to
participate via Local Optical Committees. Results were submitted via a Google form or a Microsoft Excel document and
were analysed in Microsoft Excel.
Results: Seventy-five percent of patients were managed in optometric practice. Nine and 16% of patients required
subsequent referral to their General Practitioner or hospital ophthalmology department, respectively. Should they not
have been seen, 34% of patients would have presented to accident and emergency departments and 59% to their
general practitioner. 53% of patients paid privately for the optometrist appointment, 28% of patients received a free
examination either through use of General Ophthalmic Service sight tests (9%) or optometrist good will (19%) and
19% of patients did not receive a consultation and were redirected to other providers (e.g. pharmacy, accident and
emergency or General Practitioner). 88% of patients were satisfied with the level of service. Cost-analyses revealed a
theoretical cost saving of £3198 to the NHS across our sample for the study period, indicating cost effectiveness.
Conclusions: This assessment demonstrates that a minor eye condition service in the local areas would be economically
and clinically viable and well received by patients.
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Etude cinétique et optimisation multicritères du couplage déshydratation imprégnation par immersion : séchage convectif de la poire, la pomme et l'abricot / Kinetic investigation and multicriteria optimization of dehydration impregnation : by soaking combined to convective drying of pear, apple and apricotDjendoubi Mrad, Nadia 20 December 2012 (has links)
Ce travail avait pour objectif l'étude de l'impact des deux procédés : la déshydratation imprégnation par immersion (DII) et le séchage convectif menés séparément ou combinés sur les transferts couplés d'eau et de saccharose et les principaux critères de qualité de fruit (écart de couleur, teneur en phénols totaux (PT), teneur en acide ascorbique (AA), retrait volumique, activité de l'eau) en prenant la poire Conférences comme modèle. L'effet des procédés sur les morceaux de poire a été appréhendé selon deux approches : (i) une étude globale de l'impact des variables de commandes sur la qualité du produit fini et (ii) une étude cinétique des composés d'intérêt nutritionnel et de la qualité (couleur, retrait, activité de l'eau).Un plan d'expériences composite centré à quatre facteurs et cinq niveaux a été établi (concentration en saccharose de la solution osmotique : 25-65%, température de DII : 20-60 °C, durée de la DII : 0,5-6,5 h, température du séchage convectif : 30-70 °C) pour étudier l'effet global des procédés sur le produit fini. En DII, les paramètres « °Brix, « durée » et « la température de la solution » ont un effet significatif (p < 0,01) sur les pertes en eau, le gain en soluté et les attributs de qualité de morceaux de poire. Les pertes en AA sont plus élevées que les pertes en PT et sont essentiellement dues à l'oxydation et à l'entraînement par l'eau. Durant le séchage convectif, les pertes en PT et en AA dépendent plus de la durée du procédé que de la température d'exposition. Elles atteignent respectivement 80% et 34% après 10 h de séchage à 30 °C. Le changement de couleur de morceaux de poire dépend de la durée et de la température de traitement et est plus prononcé en fin de séchage. Des modèles quadratiques prédictifs ont été proposés pour relier les variables de réponse (aw, différence de couleur, perte en PT et durée totale de traitement) aux paramètres opératoires des deux procédés étudiés. Cependant, la perte en AA décroit linéairement avec la durée de DII. Une optimisation multicritères en utilisant la méthodologie des surfaces de réponse (MSR) a été proposée (pertes minimales en PT et en AA, durée totale du traitement et différence de couleur réduites et une aw inférieure à 0,6) pour la combinaison DII/séchage. Les conditions optimales sont : solution osmotique à 28°C et 25°Brix, une durée de DII de 30 min et un séchage convectif à 60 °C. Par ailleurs, les effets de la température (30, 45 et 60 °C) et de l'imprégnation en saccharose par DII (10 et 65 min, 70°Brix, 30 °C) sur les isothermes de désorption et sur la température de transition vitreuse (Tg) de morceaux de poires, de pommes et d'abricots ont été déterminés. L'imprégnation en saccharose du tissu végétal atténue l'influence de la température sur sa capacité de sorption. Elle engendre un effet dépresseur de l'activité de l'eau et une augmentation de l'hygroscopicité de la poire, la pomme et l'abricot à température élevée. Les isothermes de désorption des abricots frais et enrichis en saccharose présentent un croisement des courbes marquant l'inversement de l'effet de la température sur les isothermes. La Tg dépend de la température, de la teneur en saccharose et de la teneur en eau des fruits. Pour une teneur en eau constante, l'augmentation de la température et la durée de DII se traduisent par l'augmentation de la Tg. Les digrammes de phase (Tg=f(X) et Tg=f(aw)) des fruits ont été établis à 30, 45 et 60°C et les teneurs en eau critiques ainsi que les activités d'eau critiques ont été déterminées. Une teneur en eau en fin de séchage inférieure ou égale à 0,02 g/g M.S. est recommandée pour l'obtention de morceaux de fruit stables aux niveaux microbiologique, physicochimique et rhéologique. / The aim of this work was the study of the impact of both drying processes: dehydration-impregnation by soaking (DIS) and convective drying performed separately or in combination on mass transfers of water and sucrose and on the main quality characteristics of the fruit (total difference of colour, total phenols (TP) and ascorbic acid (AA) contents, shrinking, water activity) by taking the pear Conference as a model. The processes effect on the pieces of pear was apprehended according two approaches: (i) a global study of the impact of the variables of commands on the quality of finished product and (ii) a kinetic study of nutritional compounds and the quality (colour, shrinkage, and water activity). Central Composite Design with four factors (sucrose concentration: 25-65 %, temperature: 20-60 °C, immersion time: 0.5-6.5 hr and drying temperature: 30-70 °C) at five levels each was used for pears processing. During DIS, the variables: immersion time, temperature and concentration of sucrose solution had a significant effect (p<0.01) in the loss of water, the solid gain and the quality attributes of pears. The losses in AA are higher than those in TP and are essentially due to the oxidation and the leaching with water. During the convective drying, the losses in TP and in AA depend more on the time of the process rather than the temperature of exposition. They reach respectively 80% and 34% after 10 h of drying at 30 °C. The color change of pear depends on the time and temperature of treatment and is more pronounced at the end of drying. Predictive and quadratic models were suggested to link the responses variables (aw, total colour difference, TP loss and total time treatment) to operational parameters of both studied processes. The losses in AA decrease linearly with the duration of DIS. A multicriteria optimization using response surface methodology (RSM) was proposed (minimal losses in TP and in AA, reduced total processing time and total difference in colour and an aw inferior to 0.6) for the combination DIS/convective drying. The optimal conditions are: osmotic solution at 28°C and 25°Brix, a DIS lasting 30 min and a convective drying at 60 °C. Otherwise, the temperature effects (30, 45 and 60 °C) and the sucrose impregnation by DIS (10 and 65 min, 70°Brix, 30 °C) upon the desorption isotherms and the transition temperature (Tg) of pears, apples and apricots were determined. The sucrose impregnation diminishes the influence of temperature on its sorption ability. It generates a depressing effect on water activity and a rise of pear hygroscopicity, apple and apricot at a high temperature. The desorption isotherms of fresh and sucrose impregnated apricot present a crossing of curves which mark the inverse of the effect of temperature on isotherms. The Tg depends on the temperature, the sucrose content and the fruit water content (X). For constant water content, the rise of temperature and of the duration de DIS result in the increase of Tg. The phase diagrams (Tg=f(X) et Tg=f(aw)) of fruits were established at 30, 45 and 60°C and the critical water content as well as the critical water activities were determined. Water content at the end of drying inferior or equal to 0.02 g/g d.b. is recommended to obtain stable fruit pieces at microbiological, physiochemical and rheological levels.
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Le problème de la phénoménologie chez Wittgenstein : le débat Pears-HintikkaProvencher, Olivier 23 November 2018 (has links)
Dans le cadre de leur interprétation phénoménologique de la pensée de Wittgenstein, Jaakko et Merrill B. Hintikka ont proposé un argument concernant la nature des objets de l’ontologie du Tractatus Logico-Philosophicus. Selon eux, les objets du Tractatus sont identifiables aux objets de l’épistémologie russellienne, à savoir les sense-data. Cette identification des objets tractariens aux sense-data les conduit à avancer que le symbolisme développé par Wittgenstein dans le Tractatus est un langage phénoménologique, celui dont le philosophe parle dans ses Remarques philosophiques de 1929. Dans le présent mémoire, je montre qu’il existe de bonnes raisons de douter de la vérité de la thèse des Hintikka et défends que l’interprétation non empiriste du Tractatus proposée par David Pears est plus convaincante que leur lecture phénoménologique de la philosophie du premier Wittgenstein.
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Genetic characterization and fungicide resistance profiles of Botrytis cinerea in rooibos nurseries and pear orchards in the Western Cape of South AfricaWessels, Andries Bernardus 03 1900 (has links)
Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Botrytis cinerea Pers. Fr. [teleomorph Botryotinia fuckeliana (de Bary) Whetzel] causes
serious losses of over 200 crops worldwide, including rooibos seedlings and pears. This
pathogen is characterized by morphological, physiological and genetic diversity. The genetic
diversity and population structure have not been investigated for B. cinerea populations in
South Africa. Botrytis cinerea collected from rooibos seedlings and in pear orchards in the
Western Cape of South Africa were investigated in the present study. The study was done
with the aid of microsatellite markers, the amplification of mating type alleles MAT1-1 and
MAT1-2 and determination of resistance towards various fungicides. Population dynamics
was inferred and a similar picture emerged in both production systems.
Botrytis cinerea annually causes severe losses of rooibos seedlings (Aspalathus
linearis) in nurseries situated in the Clanwilliam region. Sampling was done in five nurseries
and the cryptic species status of the isolates obtained was determined through restriction
enzyme digestion of the Bc-hch gene. All but one (206 out of 207) of the isolates belonged to
Group II or B. cinerea ‘sensu stricto’. Analysis of the B. cinerea Group II population, using
seven microsatellite loci, was performed to assess the genetic population structure. Total
gene diversity (H) was high, with a mean of 0.67. Two of the nurseries populations’ sample
sizes were severely limited after clone correction, yet 100 genotypes were discerned among
the 206 isolates genotyped. The percentage of maximal genotypic diversity (G) ranged
between 16 and 68 for the five populations, with a total value of 17 for the 100 genotypes.
One genotype, represented by 27 clones, was isolated from four nurseries. Relatively low but
significant population differentiation was observed in total between nurseries (mean FST =
0.030, P = 0.001). The distribution of mating types MAT1-1 and MAT1-2 differed significantly
from the ratio of 1:1 for the total population plus two of the nurseries’ populations. Three
nursery populations had an equal mating type distribution. The index of association (IA)
analyses suggests that the populations are asexually reproducing. Analysis of molecular
variance (AMOVA) indicated that 97% of the total genetic variation is distributed within
subpopulations. Fungicide resistance frequency against iprodione for 198 of the genotyped
isolates displayed highly varying levels of resistance amongst the five nurseries. The mean
total incidence of resistance towards iprodione was 43%, ranging from 0% to 81% for the five
nurseries. Baseline sensitivity towards pyrimethanil yielded an average EC50 value of 0.096
mg/L.
Botrytis cinerea isolates were collected from pear blossoms (Pyrus communis) in four
orchards. Two orchards in the Ceres area and two in the Grabouw area were sampled from.
A total of 181 isolates were collected from the four orchards. Incidence of blossom infection
in the orchards ranged from 3% to 17%. Overall, there was a high incidence of isolates that
had only the Boty transposable element (74%) compared to those harbouring both (Boty and
Flipper), simultaneously (transposa, 24%). One isolate examined had the Flipper element only. Cryptic species status according to restriction enzyme digestion of the Bc-hch gene
indicated that all the isolates belonged to Group II or B. cinerea ‘sensu stricto’. Analysis of
the Group II population, through the use of seven microsatellite loci, was performed to
assess the genetic population structure. Total gene diversity (H) was high, with a mean of
0.69 across all populations. Although two of the subpopulations displayed a high clonal
proportion, overall 91 genotypes were discerned among the 181 isolates. The percentage of
maximal genotypic diversity (G) ranged between 18 and 33 for the four populations, with a
total value of 14 for the 91 genotypes. One genotype, represented by 27 clones, was isolated
from all orchards. Moderate, but significant population differentiation was present in total
among orchards (mean FST = 0.118, P = 0.001). The distribution of the mating types, MAT1-1
and MAT1-2, did not differ significantly from a 1:1 ratio for the total population as well as the
subpopulations. Index of association (IA) analyses, on the other hand, suggests that the
populations reproduce asexually. Analysis of molecular variance (AMOVA) indicated that
88% of the total genetic variation is distributed within subpopulations, 9% between
subpopulations and only 3% between production areas. Fungicide resistance frequency
against fenhexamid, iprodione and benomyl varied, with the highest levels of resistance
present against benomyl and low levels of resistance seen towards iprodione and
fenhexamid.
In conclusion, this study has shown that there exist within the studied populations of
B. cinerea, obtained from rooibos nurseries and pear orchards, an adaptive capacity to
overcome current means of control. The use of population genetics to further our
understanding of how plant pathogens interact and spread throughout a given environment is
of cardinal importance in aiding the development of sustainable and integrated management
strategies. Knowledge of the dispersal of B. cinerea in the two studied cropping systems has
shed light on the inherent risk that it poses, and this together with knowledge of the levels of
resistance that occurs should serve as an early warning to help divert possible loss of control
in future. / AFRIKAANSE OPSOMMING: Botrytis cinerea Pers. Fr. [teleomorf Botryotinia fuckeliana (de Bary) Whetzel] veroorsaak
ernstige verliese van meer as 200 gewasse wêreldwyd, insluitende rooibossaailinge en pere.
Hierdie patogeen word deur morfologiese, fisiologiese, asook genetiese diversiteit
gekenmerk. Die genetiese diversiteit en populasie-struktuur van B. cinerea populasies wat in
Suid-Afrika voorkom, is nog nie ondersoek nie. Botrytis cinerea verkryg vanaf
rooibossaailinge en in peerboorde in die Wes-Kaap van Suid-Afrika is ondersoek. Hierdie
studie is met behulp van mikrosatellietmerkers, amplifikasie van die twee paringstipe gene
(MAT1-1 en MAT1-2), asook die bepaling van weerstandsvlakke teenoor verskeie
swamdoders, uitgevoer. Populasie-dinamika is afgelei en ‘n soortgelyke tendens is in beide
produksie-sisteme waargeneem.
Botrytis cinerea veroorsaak jaarliks ernstige verliese van rooibossaailinge
(Aspalathus linearis) in kwekerye in die Clanwilliam-area. Monsters is in vyf kwekerye
versamel en die kriptiese spesiestatus van die verkrygde isolate is deur restriksie-ensiemvertering
van die Bc-hch geen bepaal. Almal behalwe een (206 uit 207) isolaat het aan
Groep II of B. cinerea ‘sensu stricto’ behoort. Analise van die B. cinerea Groep II populasie,
deur middel van sewe mikrosatellietmerkers, is uitgevoer om die genetiese populasiestruktuur
te bepaal. Totale geendiversiteit (H) was hoog, met ‘n gemiddelde van 0.67.
Alhoewel twee van die kwekerye se monstergrootte erg ingeperk is ná kloonverwydering, is
daar nogtans 100 genotipes onder die 206 isolate wat geïsoleer is, waargeneem. Die
persentasie van maksimale genotipiese diversiteit (G) het tussen 16 en 68, vir die vyf
populasies, gewissel, met ‘n totaal van 17 vir die 100 genotipes. Een genotipe,
verteenwoordig deur 27 klone, is uit vier kwekerye geïsoleer. Relatief lae dog
noemenswaardige populasie-differensiasie is in totaal tussen kwekerye waargeneem (gem.
FST = 0.030, P = 0.001). Die verspreiding van die twee paringstipes (MAT1-1 en MAT1-2) het
beduidend verskil van ‘n 1:1 verhouding vir die totale populasie, asook twee van die
kwekerye se populasies. Die drie oorblywende kwekerye se populasies het egter ‘n gelyke
verdeling van die twee paringstipes getoon. Die indeks van assosiasie (IA) analises toon dat
die populasies ongeslagtelik voortplant. Analise van molekulêre variasie (AMOVA) het
aangedui dat 97% van die totale genetiese variasie binne die subpopulasies versprei is.
Hoogs variërende vlakke van weerstand tussen die vyf kwekerye teenoor die swamdoder
iprodioon, is vir die 198 isolate wat getoets is, gevind. Die totale gemiddelde frekwensie van
weerstand teenoor iprodioon was 43%, wat tussen 0% en 81% vir die vyf kwekerye gevarieer
het. Fondasie-vlak-sensitiwiteit vir pyrimethanil het ‘n gemiddelde EC50 waarde van 0.096
mg/L opgelewer.
Botrytis cinerea isolate is ook vanuit peerbloeisels (Pyrus communis L.) vanuit vier
boorde versamel, twee uit elk van die Ceres- en Grabouw-areas. In totaal is 181 isolate vanuit die vier boorde versamel. Die frekwensie van bloeiselinfeksie het tussen 3% en 17%
gewissel. Oor die algemeen was daar ‘n hoë frekwensie van isolate wat slegs die Boty
transponeerbare element teenwoordig gehad het (74%) in vergelyking met dié wat
tegelykertyd beide (Boty en Flipper) teenwoordig gehad het. Een isolaat het slegs die Flipper
element gehad. Bepaling van die kriptiese spesiestatus met behulp van restriksie-ensiemvertering
van die Bc-hch geen het aangedui dat alle versamelde isolate tot Groep II of B.
cinerea ‘sensu stricto’ behoort het. Analise van die Groep II populasie, deur middel van sewe
mikrosatellietmerkers, is uitgevoer om genetiese populasie-struktuur te bepaal. Totale
geendiversiteit (H) was hoog, met ‘n gemiddelde van 0.69 oor alle populasies. Alhoewel twee
subpopulasies ‘n hoë klonale fraksie getoon het, is 91 genotipes tussen die 181 isolate wat
verkry is, onderskei. Die persentasie van maksimale genotipiese diversiteit (G) het tussen 18
en 33 vir die vier populasies gewissel, met ‘n totale waarde van 14 vir die 91 genotipes. Een
genotipe, verteenwoordig deur 27 klone, was in al vier boorde teenwoordig. Gematigde dog
beduidende populasie differensiasie was in totaal tussen boorde teenwoordig (gem. FST =
0.118, P = 0.001). Die verspreiding van die paringstipes (MAT1-1 en MAT1-2) het nie
betekenisvol van ‘n 1:1 verhouding vir die totale populasie, insluitende die subpopulasies,
verskil nie. Indeks van assosiasie (IA) analises het egter aangedui dat die populasies
ongeslagtelik voortplant. Analise van molekulêre variasie (AMOVA) het aangedui dat 88%
van die totale genetiese variasie in subpopulasies te vinde was, 9% tussen subpopulasies en
slegs 3% tussen produksie-areas. Frekwensie van swamdoder weerstandbiedendheid vir
fenhexamid, iprodioon en benomyl het gewissel, met die hoogste vlakke teenoor benomyl
waargeneem, maar baie lae vlakke teenoor fenhexamid en iprodioon.
Samevattend het hierdie studie getoon dat die populasies van B. cinerea wat in
hierdie twee produksie-sisteme, op rooibossaailinge en in peer boorde, ondersoek is, ‘n
aanpasbaarheid toon om huidige metodes van beheer te oorkom. Die gebruik van populasiegenetika
as ‘n hulpmiddel om ons kennis van patogeen-interaksies en -verspreiding te
verbreed, is van kardinale belang in die ontwikkeling van geïntegreerde en volhoubare
beheermaatreëls. Kennis van die verspreiding van B. cinerea in die bestudeerde
gewasproduksiestelsels, werp lig op die inherente risiko wat dié patogeen inhou. Dít, tesame
met kennis van die weerstandsvlakke wat voorkom, kan as ‘n vroegtydige waarskuwing dien
ten einde moontlike verlies van beheer in die toekoms te help teenwerk.
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