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The inoculum ecology of Botrytis cinerea in Rooibos nurseriesSpies, Christoffel, F. J. (Christoffel Frederik Jakobus) 04 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2005. / ENGLISH ABSTRACT: Grey mould, caused by Botrytis cinerea, is the most important foliar disease of rooibos
seedlings. Although the disease is primarily controlled with applications of fungicides, the
improvement of cultural methods of disease management should lessen this dependence on
chemical control. Such improvements would, however, not be possible without knowledge of
the inoculum sources and dispersal of the pathogen. The aim of this study was to investigate
the inoculum ecology of B. cinerea in rooibos nurseries in order to identify primary sources of
inoculum and to improve the environmentally friendly management of the disease.
The study was conducted in four nurseries over two production seasons (March to July
2003 and 2004). Levels of airborne inoculum of B. cinerea were monitored on a monthly basis
inside and around the nurseries with spore traps. Samples of plant material and organic debris
were taken in the corresponding areas to determine the incidence of plant material infected by
the pathogen and the incidences of grey mould in the nurseries were recorded. Low numbers
of B. cinerea colonies were observed on the spore traps. Similar levels of airborne inoculum
were observed inside and around the nurseries. The incidence of plant material yielding B.
cinerea was higher outside the nurseries than inside, indicating the importance of such
materials as potential sources of inoculum. Since patterns of airborne inoculum observed in
this study confirmed reports of the local dispersal of B. cinerea, the removal of possible hosts
outside the nurseries could aid in the management of grey mould in rooibos nurseries.
Resistance to dicarboximide fungicides is a genetically stable trait in B. cinerea, and
therefore has the potential to be used as a phenotypic marker. This marker can be used to gain
knowledge on the dispersal of B. cinerea inoculum inside and outside rooibos nurseries.
Isolates of B. cinerea collected from the air and from plant material in and around four rooibos
nurseries were assessed for resistance to iprodione at 1 and 3 μg/ml a.i. Some of the isolates
showed resistance to iprodione at 1 μg/ml a.i. However, none of the isolates showed resistance
at 3 μg/ml a.i. iprodione. The initial incidence of dicarboximide-resistance at the nurseries was
slightly higher than expected. As the season progressed, the incidence of iprodione-resistant
isolates decreased towards May, after which an increase was observed towards July. A
relatively high percentage of isolates collected outside the nurseries was found to be dicarboximide-resistant. Two of the nurseries had a significant higher incidence of resistant
isolates on plant material collected inside, than on plant material collected outside the nursery.
However, when looking at resistance levels of airborne isolates, no significant differences were
found in the incidence of resistant isolates sampled inside and outside the four nurseries. The
data indicated the importance of organic debris and seed-borne infections in the survival and
dispersal of dicarboximide-resistant isolates of the pathogen.
With the current emphasis on organic agriculture the knowledge gained in this study
presents valuable possibilities of improving the cultural management of grey mould in rooibos
nurseries. / AFRIKAANSE OPSOMMING: Vaalvrot, veroorsaak deur Botrytis cinerea, is die belangrikste bo-grondse siekte van
rooibossaailinge. Alhoewel die beheer van die siekte hoofsaaklik op die gebruik van
fungisiede berus, behoort die verbetering van verbouingspraktyke hierdie afhanklikheid van
chemiese beheer te verminder. Sulke verbeteringe sal egter slegs moontlik wees indien
voldoende kennis van die inokulumbronne en verspreiding van die patogeen beskikbaar is. Die
doel van hierdie ondersoek was om die inokulum ekologie van B. cinerea in rooibos kwekerye
te ondersoek sodat primêre inokulumbronne opgespoor en omgewingsvriendelike
siektebestuurspraktyke verbeter kan word.
Die ondersoek is in vier kwekerye oor twee produksie seisoene (Maart tot Julie 2003 en
2004) uitgevoer. Vlakke van luggedraagde inokulum van B. cinerea is op ’n maandelikse basis
met behulp van spoorvangers binne en buite die kwekerye gemonitor. Monsters van
plantmateriaal en organiese materiaal is in ooreenstemmende areas geneem om die voorkoms
van B. cinerea geïnfekteerde plantmateriaal vas te stel en die voorkoms van vaalvrot in die
kwekerye is aangeteken. Min B. cinerea kolonies is op die spoorvangers waargeneem.
Soortgelyke vlakke van luggedraagde inokulum is binne en buite die kwekerye waargeneem.
Die hoër voorkoms van B. cinerea geïnfekteerde plantmateriaal buite die kwekerye as binne,
dui op die belang van sulke materiaal as potensiële inokulumbronne. Aangesien die patrone
van luggedraagde inokulum, soos waargeneem in hierdie ondersoek, ander berigte van B.
cinerea se beperkte verspreidingsvermoë bevestig, kan die verwydering van moontlike
alternatiewe gashere buite die kwekerye die bestuur van die siekte binne die kwekerye
verbeter.
Weerstand teen dikarboksimied fungisiede is ’n geneties-stabiele kenmerk in B. cinerea
en het daarom potensiaal om as ’n fenotipiese merker gebruik te word. Hierdie merker kan
gebruik word om kennis aangaande die verspreiding van B. cinerea in en om rooibos kwekerye
in te samel. Botrytis cinerea isolate in lug en op plantmateriaal in en om vier rooibos
kwekerye is gedurende 2003 en 2004 versamel. Die isolate is vir weerstandbiedendheid teen
iprodioon by konsentrasies van 1 en 3 μg/ml aktiewe bestandeel (a.b.) getoets. Isolate met
weerstand teen 1 μg/ml a.b. iprodioon is waargeneem, maar nie teen 3 μg/ml nie. Die aanvanklike voorkoms van dikarboksimiedweerstand by die kwekerye was hoër as verwag.
Hierdie vlak het egter gedaal met die verloop van die seisoen tot in Mei, waarna ’n toename tot
in Julie waargeneem is. Die persentasie dikarboksimied-weerstandbiedende isolate buite die
kwekerye was relatief hoog. In twee van die kwekerye was die voorkoms van
weerstandbiedende isolate op plantmateriaal in die kwekerye betekenisvol hoër as op
plantmateriaal buite die kwekerye. Daar was egter geen betekenisvolle verskille in die
voorkoms van luggedraagde weerstandbiedende isolate nie, ongeag van die kwekery of posisie.
Die data dui op die belang van organiese materiaal en saadgedraagde infeksies in die oorlewing
en verspreiding van dikarboksimied-weerstandbiedende isolate van die patogeen.
Met die huidige klem op organiese landbou bied die inligting wat in hierdie ondersoek
versamel is moontlike praktyke wat geïmplementeer kan word om die beheer van vaalvrot in
kwekerye met behulp van verbouingspraktyke te verbeter.
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The functional analysis of Vitaceae polygalacturonase-inhibiting protein (PGIP) encoding genes overexpressed in tobaccoVenter, Alida 03 1900 (has links)
Thesis (MScAgric (Viticulture and Oenology. Wine Biotechnology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Agriculture worldwide is under great pressure to produce enough food in order to sustain the
ever-growing world population. Among the many challenges faced by food producers, crop
losses and damage caused by fungal plant pathogens is a major problem. The study of fungal
pathogens and the interaction between plants and fungi is therefore essential, and has been
carried out for many years. Much has been learned in this time, but the full mechanisms of the
various modes of fungal attack and plant defence have still not been elucidated.
Many fungi rely on the action of cell-wall degrading enzymes (CWDEs) to breach the
plant cell wall and facilitate access to the nutrients within. CWDEs are among the very first
enzymes to be secreted at the start of fungal attack, and many of them are considered to be
essential pathogenesis factors. Endopolygalacturonases (ePGs) are CWDEs that cleave the
homogalacturonan stretches of the plant cell wall and are vital virulence factors for a number of
fungi, including Botrytis cinerea. An important defence mechanism of plants involves the
inhibition of CWDEs in order to halt or slow down the fungal attack. Plant polygalacturonaseinhibiting
proteins (PGIPs) are cell wall associated CWDE-inhibiting proteins that specifically act
on fungal ePGs. Many different PGIPs from a number of diverse plant species have been
described to date. They are known to have differential inhibition capabilities that often result
from only a few key amino acid changes within the leucine-rich repeat (LRR) active domains.
Previously, the first grapevine PGIP was isolated and characterised from Vitis vinifera
cultivar Pinotage (Vvpgip1). This Vvpgip1 gene was overexpressed in the tobacco species
Nicotiana tabacum, and was shown to be very effective in reducing the susceptibility of tobacco
towards B. cinerea. The combined results confirmed transgene overexpression, increased PGIP
activity and a strong resistance response against Botrytis, leading to the characterisation of
these lines as having PGIP-specific resistance phenotypes. In a subsequent transcriptomic
analysis of these lines it was found that they display differential expression of cell wall
metabolism genes and biochemical characteristics that might indicate possible cell wall
strengthening compared to wild-type tobacco under uninfecting conditions.
The V. vinifera cultivars are all very susceptible to fungal attack, whereas other
grapevine species, specifically the North American Vitis species, are known for their strong
resistance and even immunity against many fungal pathogens. Thirty seven PGIPs have
previously been isolated from these more resistant species. The amino acid sequences of the
active domains of these PGIPs were previously aligned with that of VvPGIP1, and the proteins
were found to be highly homologous with each other and with VvPGIP1. The different nonvinifera
PGIPs separated into 14 subgroups based on their active domain sequences. For this
study, one PGIP from each group was selected for functional analysis in tobacco.
The selected PGIP-encoding genes were transformed into tobacco by means of
Agrobacterium tumefaciens. Analyses of the putatively transformed plantlets were performed to
test for transgene presence, transgene expression, and PGIP activity: final transgenic tobacco
populations consisting of three to twelve individually transformed lines of nine different nonvinifera
PGIPs were obtained. A subset of the resultant transgenic lines was infected with B.
cinerea in two independent whole plant infections over 11-14 days in order to investigate the
disease resistance afforded by the various PGIPs towards this fungus. A line from the
previously characterised VvPGIP1 population was included as reference; all the infections were
contrasted to the WT tobacco. All the infected lines overexpressing the non-vinifera PGIPs
displayed very strong disease reduction in comparison to the WT control: after initial primary
lesion formation, the spread of fungal infection was contained and halted in these lines, while
wild-type tobacco plants were severely affected. Although the VvPGIP1 line displayed the characteristic PGIP-defense response, the non-vinifera PGIP plants displayed smaller lesions,
indicating very strong resistance phenotypes.
The characterised non-vinifera PGIP overexpressing lines, together with the VvPGIP1
line and the WT control were also used to further evaluate the previous observation that
overexpression might lead to changes in expression of cell wall genes. Analysis of the
expression of a xyloglucan endotransglycosylase (xth) gene in the transgenic population
showed that this gene was down-regulated in healthy uninfected tissue from all the transgenic
lines tested. This confirmed previous results and have confirmed in all grapevine PGIP
overexpressing lines tested so far that this gene is downregulated. XTH is typically involved in
cell wall metabolism and specifically in controlling the strength and elasticity of the plant cell
wall. From previous work it is known that downregulation of this gene leads to strengthening of
the wall.
The results obtained in this study showed that the PGIP-specific resistance phenotype
seen for VvPGIP1-overexpressing tobacco could be confirmed in transgenic tobacco
overexpressing non-vinifera PGIPs from more resistant grapevine species as well. The fact that
these PGIPs lines all performed even better than the VvPGIP1 lines in conferring resistance
towards B. cinerea provides an interesting angle for further investigation into the structural
differences between the non-vinifera PGIPs and VvPGIP1. The transgenic lines are also
excellent material to study the in vivo functions of PGIPs further in the context of plant-pathogen
interactions. / AFRIKAANSE OPSOMMING: Die landboubedryf is wêreldwyd onder groot druk om genoeg voedsel te produseer vir die
groeiende wêreldbevolking. Een van die grootste probleme wat die bedryf ondervind, is die
groot skade wat aan gewasse aangerig word deur patogeniese swamme. Dit is dus noodsaaklik
om swamme en die interaksie tussen plante en swamme te bestudeer, en dit word al vir jare
gedoen. Hoewel daar al baie geleer is in hierdie tydperk, is die volle meganismes van die
verskeie maniere hoe swamme aanval en hoe plante hulleself verdedig, nog nie bekend nie.
Verskeie swamme maak staat op die aktiwiteit van selwand-afbrekende ensieme
(SWAEe) om deur die plantselwand te breek en sodoende toegang tot voedingstowwe in die
plantsel te fasiliteer. SWAEe is van die eerste ensieme wat tydens die begin van patogeniese
aanval deur swamme afgeskei word en verskeie SWAEe word as noodsaaklike patogeniese
faktore beskou. Endopoligalakturonases (ePGs) is SWAEe wat die homogalakturoniese dele
van die plantselwand verteer en is noodsaaklike virulensie faktore vir ‘n aantal swamme, onder
andere Botrytis cinerea. ‘n Belangrike weerstandsmeganisme van plante behels die inhibering
van swam SWAEe om sodoende die patogeen-aanval te stop of te vertraag. Die
poligalakturonase-inhiberende proteïne (PGIPs) van plante is selwand-geassosieerde SWAEinhiberende
proteïne wat spesifiek teen swam ePGs optree. Verskeie verskillende PGIPs vanuit
verskillende plantspesies is tot dusver beskryf. Dit is bekend dat hulle differensiële inhiberende
vermoëns het wat dikwels toegeskryf kan word aan slegs ‘n paar belangrike
aminosuurvolgordeverskille in die leusien-ryke herhalende (LRH) aktiewe areas.
Die eerste wingerd PGIP is vantevore geïsoleer vanuit Vitis vinifera kultivar Pinotage
(Vvpgip1) en gekarakteriseer. Hierdie Vvpgip1 geen is ooruitgedruk in die tabakspesie
Nicotiana tabacum en was baie effektief om die weerstand van tabak teen die swam Botrytis
cinerea te verhoog. Die ooruitdrukking van die transgeen, verhoogde PGIP aktiwiteit en goeie
weerstand teen Botrytis cinerea is bevestig, en het gelei daartoe dat die transgeniese VvPGIP1
plantlyne geklassifiseer is as lyne met PGIP-spesifieke weerstandsfenotipes. ‘n
Daaropvolgende transkriptomiese analise van die plantlyne het gewys dat hulle differensiële
uitdrukking van selwand-geassosieerde gene het, asook biochemiese eienskappe, wat ‘n
moontlike selwandversterking aandui in vergelyking met wilde-tipe tabak in die afwesigheid van
infeksie.
Die V. vinifera kultivars is hoogs vatbaar vir swamme, terwyl ander wingerdspesies,
spesifiek die Noord-Amerikaanse spesies, bekend is vir hoë weerstand en selfs immuniteit
teenoor verskeie patogeniese swamme. Sewe-en-dertig PGIPs is vantevore geïsoleer vanuit
hierdie meer weerstandbiedende spesies. Die aminosuurvolgordes van die aktiewe areas van
hierdie PGIPs is vantevore vergelyk met die van VvPGIP1 en dit is gevind dat hierdie proteïne
hoogs homoloog is aan mekaar, sowel as aan VvPGIP1. Die verskillende nie-vinifera PGIPs het
in 14 groepe verdeel na aanleiding van die homologie van hulle aktiewe areas. Vir hierdie studie
is een PGIP vanuit elkeen van hierdie groepe gekies vir verdere funksionele analise in tabak.
Die 14 nie-vinifera PGIP-koderende gene is stabiel oorgedra na tabak deur middel van
Agrobacterium tumefaciens. Die vermeende transgeniese plante is geanaliseer vir die
teenwoordigheid van die transgeen, die uitdrukking daarvan en PGIP aktiwiteit: bevestigde
transgeniese tabak populasies wat wissel van drie tot 12 individuele getransformeerde lyne kon
verkry word vir nege van die verskillende nie-vinifera PGIPs. ‘n Aantal van die transgeniese lyne
is geïnfekteer met B. cinerea in twee onafhanklike heelplantinfeksies vir 11-14 dae om die
siekteweerstand van hierdie PGIPs teenoor die swam te evalueer. ‘n Plantlyn van die
VvPGIP1-populasie is as ‘n verwysing ingesluit en al die infeksies is vergelyk met die wilde-tipe
tabak. Al die geïnfekteerde lyne wat die nie-vinifera PGIPs ooruitdruk het ‘n baie sterk afname in siektesimptome getoon in vergelyking met die wilde-tipe kontrole: na aanvanklikle primêre
lesies gevorm het, is die verspreiding van die infeksie ingeperk en gestop in hierdie lyne, terwyl
die wilde-tipe plante baie erg geaffekteer is. Terwyl die VvPGIP1 lyn ook die tipiese PGIPweerstandsrespons
getoon het, het die nie-vinifera PGIPe kleiner lesies ontwikkel, wat dui op
baie sterk weerstandsfenotipes.
Die gekarakteriseerde nie-vinifera PGIP ooruitdrukkende lyne, asook die VvPGIP1 lyn
en die wilde-tipe kontrole, is gebruik om die vorige waarneming dat die ooruitdrukking kan lei tot
veranderinge in selwandgeen-uitdrukking verder te ondersoek. Analise van die uitdrukking van
‘n xiloglukaan-endotransglikosilase (xth) geen in die transgeniese populasie het getoon dat
hierdie geen afgereguleer is in gesonde, oninfekteerde weefsel van al die transgeniese lyne wat
getoets is. Dit het vorige resultate bevestig en het ook bevestig dat hierdie geen afgereguleer is
in alle wingerd PGIP-ooruitdrukkende lyne wat tot dusver getoets is. XTH is tipies betrokke by
selwandmetabolisme, spesifiek by die beheer van selwandsterkte en selwandelastisiteit. Dit is
uit vorige werk bekend dat die afregulering van hierdie geen lei tot versterking van die
plantselwand.
Die resultate verkry tydens hierdie studie het gewys dat die PGIP-spesifieke weerstand
fenotipe van VvPGIP1-ooruitdrukkende tabak ook bevestig kon word in transgeniese tabak wat
nie-vinifera PGIPs vanuit meer weerstandbiedende wingerdspesies ooruitdruk. Die feit dat
hierdie PGIP lyne almal selfs beter weerstand teen B. cinerea bied as VvPGIP1 lyne is ‘n
interessante invalshoek vir opvolgende ondersoeke na die belang van strukturele verskille
tussen die nie-vinifera PGIPs en VvPGIP1. Hierdie transgeniese lyne is ook uitstekende
hulpbronne om die in vivo funksies van PGIPs verder te bestudeer in die konteks van plantpatogeen
interaksies.
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Thin monolithic slow-release devices for optimum in-package preservation of export table grape varietiesOpperman, Willem Jacobus 03 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2002 / ENGLISH ABSTRACT: Prototypes of a new polymer S02 gas-generating sheet for the control
of Botrytis cinerea during the post-harvest storage of table grapes, were
developed and manufactured for evaluation using a pilot scale production
plant. Attention was paid to the appearance of the sheet, in order to make it
technologically efficient as well as aesthetically acceptable to both industry and
consumers.
The storage quality of semi-commercial export consignments of various
cultivars table grapes packed with the monolithic thin-film polymer S02 slow
release sheet, was evaluated and compared to results obtained using the
locally manufactured Uvasys S02 sheet. The following were investigated: the
efficacy of the new polymer sheets in controlling storage decay, the stage at
which S02 damage is manifested on table grapes, the level of S02 damage
associated with different S02 concentrations, whether S02 damage is
manifested more readily at a particular position on the bunch, and the possible
effect of an increase in storage temperature, from an initial storage at -O.5°C
to 10°C, on the levels of S02 bleaching.
Results showed that the new polymer S02 sheet compared favourably
with the existing, commercially available Uvasys S02 sheets. The exact S02
concentration required for effective decay control varied for different cultivars,
as well as for the different types of grape packages. The S02 concentration
incorporated within the sheet was shown to be lower for grapes packed in
non-perforated bags, and slightly higher for those in perforated bags.
Differences between cultivars occurred with regard to the level of control and
the levels of S02 damage. Levels of S02 damage were also significantly
affected by the storage period and temperature fluctuations. No significant
differences in the levels of decay development and S02 damage were
observed in relation to the orientation of the bunches in the carton.
The extent of damage incurred to grape tissue by the absorption of
S02 gas was determined by low-temperature scanning (LTSEM) and
transmission electron microscopy (TEM) techniques. LTSEM and TEM
micrographs of areas damaged by S02 gas revealed that exposure to S02
gas may lead to plasmolysis and the loss of cellular fluids. Although damage
to the cell walls, cell wall structures and cell membranes, caused by S02 gas,
was more prominent in the tissue layers nearer to the fruit surface, damage
also occurred to a lesser extent in deeper tissue layers.
S02 gas release-rate studies of polymer S02 sheets containing
various concentrations Na2S205 revealed that levels of S02 gas emitted
depended largely on the levels of Na2S205 incorporated into the sheets.
Higher levels of S02 gas were released with the polymer sheets of higher
concentrations Na2S205. The release curve for the commercial Uvasys S02
sheet was very different to that of the polymer sheets, with much higher levels
of S02 gas emitted initially by the Uvasys S02 sheet compared to the polymer
sheets, while the polymer sheets emitted low levels of S02 gas for longer
periods compared to the Uvasys S02 sheet.
The manufacturing process and the pilot scale production plant that
was developed and constructed was successfully used to manufacture
polymer S02 generating sheets that are technically sound and efficient, and
aesthetically acceptable to industry. The efficacy of such sheets, regarding
levels of decay control and S02 damage, was similar to that obtained with the
presently available, commercially used Uvasys S02 sheet. / AFRIKAANSE OPSOMMING: 'n Nuwe polimeriese S02-gasvrystellingsvel vir die beheer van Botritis
cinerea gedurende die na-oes opberging van tafeldruiwe is ontwikkel en
vervaardig. 'n Nuwe loodsaanleg is spesiaal vir hierdie doel ontwerp en
gebou. Aandag is geskenk aan die voorkoms van die velle aangesien dit
belangrik is dat die nuwe velle beide tegnologies effektief en esteties
aanvaarbaar moet wees vir die sagtevrugtebedryf en verbruikers.
Die opbergingskwaliteit van semi-kommersiële uitvoerbesendings van
verskeie kultivars tafeldruiwe, verpak met die nuwe monolitiese S02-
gasvrystellingsvelle, is bepaal. Die volgende is ook bepaal: die effektiwiteit
van die nuwe polimeriese velle, die stadium waarby S02-skade op die druiwe
duidelik word, die vlak van S02-skade wat met verskillende konsentasies
S02-gas geassosieer is, die moontlike invloed wat 'n toename in temperatuur
(vanaf -0.5° tot 1DOC) op die verbleiking deur S02 sal hê, en of die S02-skade
by voorkeur in 'n sekere posisie op die druiwe sal plaasvind.
Die nuwe S02-vel het baie goed vergelyk met die kommersieël
beskikbare Uvasys S02-vel. Die S02-konsentrasie benodig vir die effektiewe
beheer van Botritis cinerea beskadiging het egter van kultivar tot kultivar
verskil. Die keuse van die tipe verpakking, geperforeerd of ongeperforeerd,
het ook 'n rol gespeel. Die konsentrasie S02-gas benodig vir effektiewe
beheer was laer wanneer die druiwe in die nie-geperforeerde sakke verpak
was. Vlakke van S02-skade is ook noemenswaardig beïnvloed deur die
opbergingsperiode en variasies in temperatuur. Daar was geen duidelike
verskil in die ontwikkeling van bederf en S02-skade ten opsigte van die
posisie van die trosse in die karton nie.
Die mate van S02-skade aan vrugweefsel is deur middel van laetemperatuurskandeerelektronmikroskopie
(LTSEM) en transmissieelektronmikroskopie
(TEM) bepaal. Daar is bevind dat die blootstelling aan
S02 moontlik tot plasmolise en die uitlek van sellulêre vloeistof kon lei.
Alhoewel S02-skade aan die selwande en membrane meer prominent in die weefsel naby die oppervlak van die vrug was, het skade ook in die
onderliggende lae plaasgevind.
Die vlakke van vrygestelde S02-gas het grootendeels afgehang van
die konsentrasie natriummetabisulfiet in die velle. Die S02-vrystellingskurwe
van die nuut ontwikkelde polimeriese S02-velle het baie verskil van dié van
die Uvasys vel. Laasgenoemde lewer aanvanklik 'n hoë konsentrasie
vrygestelde S02-gas vir 'n kort periode, gevolg deur baie lae S02 vlakke
daarna, terwyl eersgenoemde 'n laer aanvanklike S02 vrystelling het, gevolg
deur vergelykederwys hoër S02 konsentrasies daarna.
Die ontwikkelde vervaardigingsproses en die loodsaanleg wat daaruit
voortgevloei het is dus suksesvol aangewend om goeie polimeriese S02-
vrystellingsvelle te vervaardig. Hierdie velle is tegnies effektief vir die beheer
van Bofrifis cinerea gedurende die na-oes verpakking van tafeldruiwe en is
esteties aanvaarbaar vir die Suid Afrikaanse sagtevrugtebedryf.
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Enhancing ecosystem services in vineyards to improve the management of Botrytis cinereaJacometti, Marco Alexander Azon January 2007 (has links)
Organic mulches and cover crops mulched in situ were assessed for their effects on B. cinerea primary inoculum and disease levels in inflorescences at flowering and/or bunches at harvest.
Organic mulches were used to enhance biological degradation of vine debris to reduce levels of B. cinerea primary inoculum the following season. Four mulch types (anaerobically and aerobically fermented marc (grape pressings), inter-row grass clippings and shredded office paper) were applied under ten-year-old Riesling vines in a ten-replicate randomized block design in New Zealand over two consecutive years. Plastic mesh bags, each containing naturally infected vine debris, were placed under vines on bare ground (control) and at the soil-mulch interface, in winter (July) 2003 and 2004. In each year, half the bags were recovered at flowering (December) and the remainder at leaf plucking (February), for assessment of B. cinerea sporulation from the vine debris and debris degradation rate. Bait lamina probes, which measure soil biological activity, were placed in the soil-mulch interface three weeks before each of the two bag-recovery dates in both years and were then removed and assessed at the same times as were the bags. All mulches led to a reduction in B. cinerea sporulation. This reduction was significantly correlated with elevated rates of vine debris decomposition and increased soil biological activity. Over both years, compared with the controls, all treatments gave a 3-20-fold reduction in B. cinerea sporulation, a 1.6-2.6-fold increase in vine debris degradation and in the two marc and the paper treatments, a 1.8-4-fold increase in activity of soil organisms.
The mulches also altered vine characteristics and elevated their resistance to B. cinerea through changes to the soil environment. Functional soil biological activity, as measured by Biolog Ecoplates and bait lamina probes, was increased 2-4 times in the two marc and paper treatments, compared with the control, an effect relating to the elevated soil moisture and reduced temperature fluctuations under these mulches. Soil nutrient levels and the C:N ratios were also affected in these treatments. The mulched paper lowered vine canopy density by up to 1.4 times that of the other treatments, an effect which probably led to elevated light penetration into the canopy and consequent increased canopy temperature, photosynthesis and lowered canopy humidity. These changes to soil and vine characteristics increased grape skin strength by up to 10% in the paper treatment and sugar concentrations by 1.2-1.4 °Brix in the two marc and paper treatments. The severity of B. cinerea infections in the anaerobic marc, aerobic marc and paper treatments were reduced to 12%, 3% and 2.2% of the control, respectively, in field assessments averaged over two consecutive harvests.
Cover crops mulched in situ had similar effects to those of the organic mulches, increasing soil biological activity and reducing B. cinerea primary inoculum and the severity of B. cinerea infection in grapes at harvest (2006). Inter-row phacelia and ryegrass were mulched in winter 2005 and compared with a bare ground control, under 10-year-old Chardonnay vines in a ten-replicate randomized block design. Functional soil biological activity increased by 1.5-4.5 times in the two cover crop treatments compared with the control, an effect possibly related to elevated soil moisture in these treatments. This increase in soil moisture and soil biological activity increased vine debris degradation, reduced B. cinerea primary inoculum on the debris and decreased B. cinerea severity at flowering (December 2005) and harvest (April 2006).
These results show the potential of organic mulches and cover crops mulched in situ to enhance soil ecosystem services and improve the sustainability of viticultural practices.
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Estimation du potentiel de résistance de Botrytis cinerea à des biofongicidesAjouz, Sakhr 21 December 2009 (has links) (PDF)
La pourriture grise, causée par le champignon Botrytis cinerea, est l'une des principales maladies aériennes fongiques sur diverses cultures d'importance agronomique. La diversité génétique de B. cinerea est très forte et la capacité rapide d'adaptation de ce champignon à une pression sélective est également avérée. Ce champignon est ainsi capable de développer des résistances à une grande variété de composés fongicides de synthèse ou d'origine naturelle. Des méthodes alternatives de lutte ont de ce fait été développées ces dernières années : divers agents de lutte biologique (ALB) présentant différents modes d'actions ont été identifiés et pour certains d'entre eux commercialisés pour contrôler B. cinerea. Cependant la durabilité de la lutte biologique est un domaine encore très peu étudié. La perte d'efficacité d'un ALB pourrait résulter de la préexistence d'isolats moins sensibles de pathogènes dans les populations naturelles et/ou de la capacité de l'agent pathogène à produire, sous une pression de sélection continue exercée par l'ALB, des mutants ayant une sensibilité réduite. L'objectif global de la présente étude est d'évaluer le risque potentiel de perte d'efficacité de la lutte biologique vis-à-vis de B. cinerea. Dans cette étude, les efforts ont été concentrés sur la pyrrolnitrine, un antibiotique produit par divers ALBs, dont certains sont efficaces contre B. cinerea. Les objectifs spécifiques de l'étude étaient (i) d'évaluer la diversité de la sensibilité à la pyrrolnitrine au sein de la population naturelle de B. cinerea, (ii) d'estimer le risque de perte d'efficacité des ALBs produisant la pyrrolnitrine due à la pression de sélection exercée par la pyrrolnitrine et (iii) d'étudier le mécanisme de résistance à la pyrrolnitrine chez B. cinerea. Parmi 204 isolats de B. cinerea, une gamme importante de sensibilité à la pyrrolnitrine a été observée, avec un facteur de résistance de 8,4 entre l'isolat le plus sensible et l'isolat le moins sensible. La production de 20 générations successives pour 4 isolats de B. cinerea, sur des doses croissantes de pyrrolnitrine, a abouti au développement de mutants avec des niveaux élevés de résistance à l'antibiotique, et à une réduction in vitro de la sensibilité à la bactérie productrice de pyrrolnitrine Pseudomonas chlororaphis PhZ24. La comparaison entre les mutants résistants à la pyrrolnitrine et leurs parents sensibles pour la croissance mycélienne, la sporulation et l'agressivité sur plantes a révélé que la résistance à la pyrrolnitrine est associée à un fort coût adaptatif. Des observations cytohistologiques sur tomates ont confirmé que l'isolat sensible à la pyrrolnitrine attaque le pétiole rapidement et envahit la tige, alors que le mutant résistant à la pyrrolnitrine ne s'étend pas au-delà du pétiole. De plus, ce dernier mutant forme un mycélium anormal et des cellules ressemblant à des chlamydospores. Les résultats ont d'autre part révélé que les mutants de B. cinerea résistants à la pyrrolnitrine sont résistants au fongicide iprodione, suggérant ainsi qu'une pression exercée par la pyrrolnitrine sur le champignon conduit à une résistance au fongicide. Réciproquement, la production de générations successives sur iprodione conduit à une résistance à l'antibiotique. Afin d'étudier les déterminants moléculaires de la résistance de B. cinerea à la pyrrolnitrine, le gène histidine kinase Bos1, impliqué entre autres dans la résistance aux fongicides chez B. cinerea a été séquencé chez les souches sensibles et les mutants résistants. La comparaison des séquences a mis en évidence des mutations ponctuelles différentes chez les mutants de B. cinerea obtenus sur la pyrrolnitrine et ceux obtenus sur l'iprodione. De plus, les résistances à la pyrrolnitrine et à l'iprodione ne sont pas systématiquement associées à une mutation ponctuelle dans le gène Bos1. Enfin, aucune modification n'a été détectée dans la taille des allèles de neuf locus microsatellites quelle que soit la pression sélective exercée et quelle que soit le phénotype du mutant produit. Cette étude montre qu'un champignon pathogène des plantes est capable de développer progressivement une moindre sensibilité à un agent de lutte biologique mais que cette moindre sensibilité est associée à une forte perte de fitness
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Epiphytic yeasts isolated from apple leaves to control of gray and blue mold fruit rots of appleFalconi, Cesar E. 14 June 1996 (has links)
Eight phylloplane yeasts were isolated from backyard apple trees in
Corvallis, OR. Yeast isolates were classified to genus or species level. All
isolates were tested in vitro for antagonistic activity against the postharvest
pathogens Botrytis cinerea and Penicillium expansum. Of these isolates,
Aureobasidium pullulans, Sporobolomyces roseus Rhodotorula sp., consistently
reduced mycelial growth of B. cinerea and P. expansum in nutrient yeast
dextrose agar (pH 4.5 or 7.0) incubated for 8 or 30 days at 24 or 1 C, respectively.
These three yeasts also were evaluated for their ability to suppress spore
germination of B. cinerea and P. expansum in a gradient of apple juice
concentrations and to suppress development of gray and blue mold lesions in
inoculated fruits of Golden Delicious apple. Germination of B. cinerea and P.
expansum was reduced significantly (P���0.05) when incubated with the yeast
isolates in 100 or 50% apple juice, but not in 0, 1 or 10% apple juice. S. roseus
and A. pullulans reduced significantly (P���0.05) the size of gray mold lesions in
wounded fruit stored at 5 C and 24 C by 63 to 72 and 81 to 90%, respectively,
when compared to the nontreated control. Size of blue mold lesions in fruit
stored at 5 and 24 C also were reduced significantly (P���0.05) by 66 to 38 and 74
to 63%, respectively, when pre-treated with S. roseus and A. pullulans. In
general, fruit rot suppression by some yeasts isolated in this study was similar in
magnitude to suppression obtained by Cryptococcus laurentii isolate 87-108, a
yeast with commercial potential to suppress postharvest rots of pome fruits.
Pretreatment of apple wounds with washed cells of A. pullulans, S. roseus,
Rhodotorula sp., resulted in disease suppression, but treatment of wounds with cell-free culture supernatant of these isolates did not affect lesion development. Population size of A. pullulans, S. roseus, and C. laurentii increased in apple wounds incubated at 5 or 24 C for up to 25 days, indicating that they colonized the wound site. Data collected in this study support the hypothesis that yeast isolates antagonize fruit pathogens by competing for nutrients in wounds on fruit surfaces. The isolates of A. pullulans and S. roseus show promise for commercial development. / Graduation date: 1997
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Hormetic UV treatments for control of plant diseases on protected edible cropsScott, George January 2017 (has links)
Hormesis is a dose response phenomenon where low doses of a stress bring about a positive response in the organism undergoing treatment. UV-C hormesis has been known for over three decades and has a broad range of benefits on postharvest produce. Benefits include increased nutritional content, delayed chlorophyll degradation and disease resistance. The beneficial effects have been observed on many varieties of fresh produce including climacteric and non-climacteric fruit, tubers, salads and brassicas. The majority of previous studies have used low-intensity (LIUV) UV-C sources. LIUV sources require lengthy treatment times, which are in the region of 6 minutes for tomato fruit. This has, in part, prevented the commercial application of this technique. High-intensity, pulsed polychromatic light (HIPPL) sources, however, have recently been developed. HIPPL sources may have the potential to drastically reduce treatment times and increase their commercial viability. It was shown, here, that the use of HIPPL can control disease (reduce disease progression) caused by Botrytis cinerea and Penicillium expansum and also delay ripening on tomato fruit. Both disease control and delayed ripening were at similar levels for LIUV and HIPPL treatments on mature green fruit. The HIPPL treatments used in these studies can reduce treatment times for tomato fruit by 97.3%. Both HIPPL and LIUV treatments elicit local responses irrespective of the treatment orientation and tomato fruit, therefore, require full surface irradiation. Furthermore, UV-C in the HIPPL source is not required for disease control or delayed ripening. It does, however, contribute approximately 50% towards the total observed effects. Investigations into the mechanisms underpinning postharvest HIPPL and LIUV hormesis, on tomato fruit, identified that the expression of genes involved in plant hormone biosynthesis, defence, secondary metabolism and ripening were affected. This indicates that disease control is achieved through induced resistance. Changes to expression, following treatment, were highly similar for both HIPPL and LIUV treatments and were mediated by salicylic acid, jasmonic acid and ethylene. This may lead to broad range resistance against necrotrophic and biotrophic pathogens as well as abiotic stresses and herbivorous pests. Recently, the exposure of foliage to UV-C has been shown to induce resistance against B. cinerea on Arabidopsis thaliana. The horticultural applications of such treatments, however, have not been explored. Pre-harvest treatments of lettuce in the glasshouse showed variation in damage threshold and optimal treatment to control disease following LIUV and HIPPL treatment. Further sources of variation included the cultivar, pathogen of interest and the point that treatment was applied during the year. Using a controlled environment allowed seasonal variation to be mitigated and both HIPPL and LIUV treatments controlled disease against B. cinerea. For pre-harvest treatments to be a success in the glasshouse, further studies into how both biotic and abiotic factors influence treatment is required. To circumvent the problems associated with pre-harvest treatments and environmental variation in the glasshouse, LIUV seed treatments were performed on tomato. Control of B. cinerea was established with an approximately 10% reduction in incidence and disease progression with a 4 kJ/m2 treatment. When monitoring the effect of treatment on germination and early seedling development it was also identified that an 8 kJ/m2 treatment led to biostimulation of germination and root and shoot growth.
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Absorção e mobilidade do boro em plantas de repolho e de couve-flor /Alves, Adriana Ursulino. January 2009 (has links)
Resumo: Objetivou-se avaliar os efeitos da omissão de boro na solução de nutrientes e de doses de boro em aplicação foliar no crescimento e na nutrição, e estudar o tempo de absorção e a sua mobilidade em plantas de repolho 'Astrus' e couve-flor 'Verona'. Para isto, foram realizados na UNESP, Câmpus de Jaboticabal, oito experimentos com as plantas do repolho 'Astrus' e da couve-flor 'Verona' no período de fevereiro de 2007 até maio de 2008. Nas duas hortaliças, estudaram-se a omissão de boro em diferentes estádios de desenvolvimento e as doses de boro (0; 0,085; 0,170; 0,255 e 0,340 g L-1) via aplicação foliar. Em seguida, estudaram-se o tempo de absorção do boro aplicado via foliar (até 30 dias após aplicação) nas hortaliças e também compararam-se a mobilidade do boro marcado (10B) absorvido pelas raízes e pelas folhas, nas folhas emitidas após a sua aplicação. Em todos os experimentos, avaliaram-se as variáveis de crescimento, nutrição e de produção de matéria seca das plantas. Verificou-se, que o efeito da deficiência de boro ficou evidente no final do ciclo das hortaliças (terceiro estádio de desenvolvimento), causando maior diminuição na parte comercial das hortaliças. A adubação foliar com o micronutriente promoveu a máxima produção de matéria seca da parte comercial e da planta inteira do repolho 'Astrus', com pulverizações foliares de B nas doses de 0,224 e 0,240 g L-1, respectivamente, e esteve associada com o teor foliar de B de 15 e 14 mg kg-1. Na couve-flor 'Verona', a massa seca da parte comercial e da planta inteira aumentaram linearmente com as doses de boro, assim como o teor foliar que variou de 14 a 25 mg kg-1. O boro é absorvido lentamente pelas folhas do repolho 'Astrus', absorvendo 50% do B aplicado, próximo de 15 dias após sua aplicação e na couve-flor 'Verona' aos três dias e 12 horas após ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The effects of boron on cabbage and cauliflower plants were analyzed under the following approaches: (1) omitting boron from the nutrient solution at different stages of plant development; (2) Foliarly application of different doses of boron: 0, 0.085, 0.170, 0.255, and 0.340 g L-1; (3) Measuring the time necessary for boron to be absorbed by the plants when the boron fertilizer is foliarly applied; (4) Determining boron mobility in the plants by means of labeled boron (10B) supplied either via foliar fertilization or the fertilizer being directly applied to the soil. The effects of those procedures were evaluated in terms of plant growth, nutrition and productivity. The results showed that the effects of boron deficiency are more clearly felt at the end of the plant cycle so that the main effect is on plant commercial value. The doses of 0.224 and 0.240 g L-1 were those resulting in the highest commercial and the whole plant yields, respectively. These doses were found to be related with B levels in the plants of 15 and 14 mg kg-1. The commercial part and the whole plant of the 'Verona' cauliflower cultivar increased linearly with doses of boron. The foliar level of boron also increased linearly from 14 to 25 mg kg-1. Boron is slowly absorbed by the leaves of the 'Astrus' cabbage cultivar: it takes almost 15 days for 50% of the total applied to be absorbed. Cauliflower plants of the 'Verona' cultivar, on the other hand, absorbed a similar proportion in 3 days and 12 hours. It was observed that boron is immobile both in cauliflower and cabbage plants suggesting that boron fertilizers should be applied directly to the soil / Orientador: Renato de Mello Prado / Coorientador: Arthur Bernades Cecilio Filho / Banca: Cassio Hamilton Abreu Junior / Banca: Francisco Maximino Fernandes / Banca: Mara Cristina Pessôa da Cruz / Banca: Leila Trevizan Braz / Doutor
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Absorção e mobilidade do boro em plantas de repolho e de couve-florAlves, Adriana Ursulino [UNESP] 18 September 2009 (has links) (PDF)
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Desempenho viti-enológico das variedades cabernet sauvignon e sauvignon blanc em regiões de altitude em função da época de desfolha / Viti-enological performance in Cabernet Sauignon and Sauvignon Blanc in highlands regions in differents leaf removal timingWürz, Douglas André 13 July 2016 (has links)
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Previous issue date: 2016-07-13 / Capes / Highland regions of Santa Catarina State, Brazil, have been acquiring great importance due to the high potential for wine production from Vitis vinifera L. cultivars, but due to highlands of Santa Catarina State are being in an emergent wine grown region fundamental investigations into vineyard practices are necessary. This work aims to contribute to the generation of data that can direct the management of leaf removal in the vineyards in order to develop a differentiated quality wine, determining times of leaf removal in the varieties Cabernet Sauvignon and Sauvignon Blanc, and evaluate the its effect on vegetative, productive aspects, enological potential of grape wine quality, and the occurrence of bunch rot. The results of this study show the importance of management of leaf removal grapes wines, demonstrating its benefits in relation to technological and phenolic maturity indices, providing better quality grape, higher productivity and better vegetative balance. And the leaf removal, held between phenological full flowering stage and grain pea resulted in a significant reduction in the incidence and severity of bunch rot of Cabernet Sauvignon and Sauvignon Blanc grown in high altitudes of Santa Catarina. It is evident that the removal leaf vine is indispensable for obtaining a grape of high quality and sanity / As regiões de altitude de Santa Catarina vem despertando interesse de investidores, pela sua característica de elaborar vinhos de elevada qualidade. Porém, por ser uma atividade ainda recente nessas regiões, há uma grande demanda pela geração de informações técnicas adequadas, visto que possui características distintas das demais regiões vitícolas do Brasil. A presente dissertação visa contribuir na geração de informações que possam direcionar o manejo da desfolha nos vinhedos, a fim de elaborar um vinho de qualidade diferenciada, determinando o efeito de diferentes épocas de desfolha nas variedades Cabernet Sauvignon e Sauvignon Blanc sobre aspectos vegetativos, produtivos, potencial enológico da uva, qualidade do vinho, e na ocorrência de podridão cinzenta (Botrytis cinerea Pers) nos cachos. Os resultados deste estudo evidenciam a importância do manejo da desfolha da videira, demonstrando seus beneficios em relação aos índices de maturação tecnológica e fenólica, propiciando melhor qualidade da uva, maior produtividade e melhor equilíbrio vegeto:produtivo. Além disso, a realização de uma desfolha precoce, realizada entre os estádios fenológicos plena florada e grão ervilha resultaram em redução da incidência e severidade de podridão cinzenta (Botrytis cinerea) nos cachos das variedades Cabernet Sauvignon e Sauvignon Blanc cultivadas em elevadas altitudes de Santa Catarina. Evidencia-se que o manejo da desfolha da videira é indispensável para obtenção de uma uva de elevada qualidade e sanidade
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