Copies of author's previously published articles inserted. / Bibliography: leaves 143-167. / xvi, 176 leaves, [17] leaves of plates : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Temperature may affect fruit-set in grapevines through its effect on the development of the flowers up to flower opening and on pollination, be it on the germination of the pollen and the growth of the pollen tube, or on the post-fertilisation growth of the ovule. / Thesis (Ph.D.)--University of Adelaide, Dept. of Horticulture, Viticulture and Oenology, 1996

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 4 uppsatser.

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2008. / Härtill 4 uppsatser.

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Thesis (MScAgric)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: The climate around Prieska differs from other pistachio growing regions in the world in that it receives fewer winter chilling units, has higher maximum temperatures during winter and spring and receives summer rainfall. This possibly results in the observed delayed foliation, flower bud and inflorescence abortion, low fruit set and other flowering disorders, which lower yield potential. In order to increase yields, winter pruning, evaporative cooling and chemical rest breaking were investigated on ‘Ariyeh’, ‘Shufra’ and ‘Sirora’ pistachio trees. Tip-pruning (to remove <2.5cm) and severe heading cuts (to remove 35-45%) of one-year old wood were compared and 4% hydrogen cyanimide (Dormex®), 4% mineral oil (Budbreak®) as well as the combination (0.5% Dormex® + 4% Budbreak®) used as rest breaking agents. Bud break, reproductive bud differentiation, die-back, flower bud retention during winter and early summer as well as yield were evaluated. The results emphasised the interaction of rest breaking and pruning effects, with genetic chill requirements and environmental influences - specifically winter chill build-up. Severe pruning was detrimental to flower bud formation as well as yield. The bud break data suggests that the ability of some rest breaking chemicals to promote lateral development may be explained by their potential to impede the development of apical dominance, rather than a direct effect on the lateral buds. The inability of the chemical treatments to increase yield consistently might indicate other factors involved or that the average winter chill of Prieska is below the minimum amount necessary for adequate rest breaking effects on yield. Evaporative cooling was used to counteract potential negative effects of high maximum day temperatures during autumn and spring on flower bud retention, fruit set and yield. Cooling during autumn (May + June, Southern hemisphere), spring (August + September, Southern hemisphere) and the combination of autumn + spring were investigated during two seasons. Flower bud retention during winter and early summer, flowering patterns, as well as yield were evaluated. The significant effects obtained with evaporative cooling - specifically in autumn + spring, indicated the important role climatic conditions play during both stages of entering and exiting dormancy of pistachio trees. Although all differences are not yet clearly understood, the fact that evaporative cooling resulted in substantially higher yields in the case of ‘Ariyeh’ and ‘Shufra’ in an area with sub-optimal pre-blossom temperatures and less than 40% of the required winter chill of pistachio, emphasises its potential in horticultural management. / AFRIKAANSE OPSOMMING: Prieska se klimaat verskil van ander pistachio-produksie areas in die wêreld deurdat minder winterkoue-eenhede opgebou word, dit hoër maksimum temperature het gedurende die winter en lente en ’n somer-reënvalgebied is. Dit dra waarskynlik by tot die waargenome vertraagde bot, blomknop- en bloeiwyse abortering, lae vrugset en ander blom-afwykings. Aangesien hierdie faktore opbrengspotensiaal verlaag, is wintersnoei, verdampingsverkoeling en chemiese rusbreking ondersoek as moontlike bestuursoplossings. Tip- (om <2.5cm te verwyder) en topsnitte (om 35-45% te verwyder) van eenjarige lote is met mekaar vergelyk en 4% waterstofsianied (Dormex®), 4% minerale olie (Budbreak®) en hul kombinasie is as rusbrekers aangewend. Bot, blomknop-differensiasie, terug-sterwing, blomknopretensie gedurende winter en vroeë somer sowel as opbrengs is geëvalueer. Die resultate benadruk die onderlinge interaksie van rusbreking- en snoei-effekte met genetiese koue-behoeftes en omgewingseffekte - spesifiek die opbou van winterkoue. Topsnitte was nadelig vir blomknopvorming, sowel as opbrengs. Die bot-data doen aan die hand dat sommige chemiese rusbrekers se potensiaal om laterale breke te bevorder, verduidelik kan word deur hul vermoë om die ontwikkeling van apikale dominansie te onderdruk, eerder as ‘n direkte effek op die laterale knoppe. Die chemiese behandelings se onvermoë om opbrengs deurggaans te verbeter, mag daarop dui dat die gemiddelde winterkoue van Prieska laer is as die minimum hoeveelheid benodig alvorens chemiese rusbreker effekte op opbrengs verwag kan word. Potensiële negatiewe effekte van hoë maksimum dagtemperature gedurende die herfs en lente op blomknopretensie, vrugset en opbrengs is teengewerk deur middel van verdampingsverkoeling. Verkoeling gedurende herfs (Mei + Junie, Suidelike halfrond), lente (Augustus + September, Suidelike halfrond) en die kombinasie van herfs + lente is gedurende twee seisoene ondersoek. Blomknopretensie gedurende winter en vroeë somer, blompatrone, sowel as opbrengs is geëvalueer. Die betekenisvolle verskille verkry met verdampingsverkoeling, dui die belangrike rol aan wat klimaatstoestande gedurende beide stadiums van in-, sowel as uitgang uit dormansie speel in pistachiobome. Hoewel alle verskille nog nie verklaar kan word nie, dien die feit dat verdampingsverkoeling tot substansiële opbrengste in die geval van ‘Ariyeh’ en ‘Shufra’ kon lei in ‘n area met suboptimale voor-bot temperature en gemiddeld minder as 40% bevrediging van die kouebehoefte van pistachios, as beklemtoning van die belang daarvan as hortologiese bestuursmiddel.

Thesis (MScAgric)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: By world standards South Africa’s contribution to fresh blueberry production is very small, a mere 0.25 %. This seemingly insignificant and unimpressive statistic is, however, by no means indicative of the impending impressive potential the South African blueberry industry holds. South Africa is encountering a rapid growth phase off a very small base and the current 100-150 ton export crop is expected to increase to a range of 500 to 600 tons or more in the next five years. Consequently, export by sea must be considered as a logistic alternative. Seafreight success relies on controlled atmosphere storage which in turn relies on berries of exceptional quality. To achieve this, fundamental differences between blueberry cultivars must be examined and blueberry handling and storage regimes must be assessed and optimised. This study investigates the storage potential of certain rabbiteye blueberries relative to controlled atmospheres and short pre-cooling delays. Quality assessments were based on external colour, soluble solids, titratible acidity, firmness and decay development. Furthermore, the respiration and ethylene production rates as well as moisture loss, of various cultivars were determined to characterize fundamental differences amongst cultivars and to gain insight into their postharvest behaviour. Lastly the effect of infection on pigment levels of blueberry flesh and peel was examined for the purpose of laboratory experience. Controlled atmosphere storage had the greatest impact on berry firmness and percentage decay. No off flavours were detected during sensory analysis at the CA levels tested. CAstored berries were firmer and incidence of decay was reduced significantly. Significant decay reduction was challenged by the market tolerance of no more than 2 %. Decay suppression and storage extension was insufficient (for the set period), particularly after the shelf life period. Cultivar and seasonal differences as well as picking maturity and inoculum pressure determine blueberry CA storability. CA may be a valuable technology, however advances must first be made in ensuring optimal blueberry quality to warrant export by sea. Short pre-cooling delays (0, 2, 4, 6 h) at 20 ºC had no effect on colour (L, C, H), total soluble solids, titratable acidity and firmness of blueberry cultivars, ‘Centurion’, ‘Premier’ and ‘Tifblue’. Results for percentage decay indicate that prompt cooling becomes more critical as the duration of storage increases, particularly when market specification of no more than 2 % decay must be met. Berries subjected to longer delays appear to be more susceptible to decay. Differences exist among cultivars and knowledge gained from this research can be used to adapt handling and cooling regimes. Information generated will benefit cultivar selection for marketing (local vs. export), storage (short vs. long term) and logistics (air vs. seafreight). Rabbiteye blueberry cultivars differ considerably in terms of their respiration rate, ethylene production and moisture loss. These quality parameters were evaluated for various cultivars at 15 ºC. ‘Climax’ appears to have the highest respiration rate, ethylene production and moisture loss, whilst ‘Premier’ has the lowest respiration rate and ethylene production was too low to be detected by gas chromatography. The lowest moisture loss proportionality constant was found for ‘Tifblue’ and ‘Centurion’. A change in blueberry flesh colour from white to dark red was noted in infected berries. Artificial inoculation with Botrytis cinerea showed a similar result. The colour change was evaluated by comparing anthocyanin pigment levels (determined by spectrophotometry and HPLC) of the peel and flesh. Anthocyanin content of infected flesh doubled, whilst that of infected peel was less than 50 % of the control. Pigment leakage has been reported in blueberries. It would appear that cell disruption, induced by infection may facilitate migration of anthocyanin from the peel to the flesh. The storage potential of blueberries depends on cultivar, maturity at harvest, climatic conditions as well as the inoculum pressure. Under favourable conditions storage life of blueberries can be manipulated effectively. Further cultivar specific research that targets relevant quality issues should be investigated. Reliable techniques should be developed to quantify blueberry firmness changes. Research on inoculum levels may give insight into the reduction of decay pressure and decay suppressing alternatives such as antibacterial pads can be examined. Peel integrity relative to decay susceptibility can also be researched on a cellular level. / AFRIKAANSE OPSOMMING: Suid-Afrika se bydrae tot wêreld bloubessie produksie is baie klein, ‘n skrale 0.25 %. Hierdie onindrukwekkende statistiek weerspieel egter glad nie die indrukwekkende potensiaal van die Suid-Afrikaanse bloubessie bedryf nie. Die bedryf ondervind tans ‘n dramatiese groei met ‘n klein begin vanaf die huidige 100-150 ton opbrengs tot wat volgens verwagting binne die volgende vyf jaar sal styg tot in die orde van 500-600 ton. Na aanleiding van die verwagte toename in produksie, sal seevrag verskeping oorweeg moet word as alternatief vir uitvoer eerder as lugvrag. Die sukses van seevrag lê in die gebruik van beheerde atmosfeer opberging (BA), waarvan die sukses op sy beurt bepaal word deur bessies van hoogstaande kwaliteit. Om steeds aan die verwagtings van die oorsese mark te voldoen moet grondliggende verskille tussen bloubessie kultivars ondersoek word en daaropvolgend moet hantering en opbergingstelsels aangepas en geoptimeer word. Die navorsing bestudeer die opbergingspotensiaal van verskeie rabbiteye bloubessies relatief tot beheerde atmosfere en kort vertragings in verkoeling. Kwaliteit, gebasseer op eksterne kleur, oplosbare deeltjies, titreerbare sure, fermheid en persentasie bederf, is ondersoek. Die respirasie en etileenproduksie tempos sowel as vogverlies van verskeie kultivars was verder bepaal om die fundamentele verskille tussen kultivars te bepaal, sowel as insig te verwerf in na-oes gedrag. Die effek van infeksie op pigment vlakke van bloubessie vlees en skil was ondersoek vir die doel van laboratorium ondervinding. Beheerde atmosfeer opberging het die grootste effek getoon op bessie fermheid en persentasie bederf. Na aanleiding van sensoriese toetse is daar geen wansmaake aangeteken ten op sigte van die BA vlakke wat getoets is nie. Bessies onderworpe aan beheerde atmosfeeriese toestande was fermer en bederfonderdrukking was beduidend. Die markverdraagsaamheid ten opsigte van bessiebederf, is egter 2 %. Hiervolgens was onderdrukking van verval asook opbergingsvermoë, onvoldoende (spesifiek na die rakleeftyd). Kultivar en seisoenale verskille asook plukrypheid en inokulum druk, bepaal ook die sukses van BA opberging. BA word beskou as ‘n waardevolle tegnologie vir verlenging van opberging. Dit blyk egter dat daar eers ‘n vooruitgang gemaak moet word in die versekering van optimale bessie kwaliteit voordat verskeping oorweeg kan word. Kort vertragings (0, 2, 4, 6 uur by 20 ºC) in verkoeling, het geen invloed gehad op kleur, (L, C, H), totale oplosbare vastestowwe, titreerbare suur en fermheid van bloubessie kultivars ‘Centurion’, ‘Premier’ en ‘Tifblue’ nie. Bederfresultate dui daarop dat onmiddelike verkoeling krities is, veral by verlengde opberging, om aan die 2 % bederf drempelwaarde te voldoen. Bessies onderhewig aan langer vertragings voor verkoeling, blyk meer vatbaar te wees vir bederf. Verskille bestaan tussen kultivars en kennis ingewin tydens hierdie navorsing kan toegepas word om hanteringsprosedures en verkoeling aan te pas. Ingeligte besluitneming kan dus ten opsigte van kultivarspesifieke bemarking (plaaslik en uitvoer), opberging (kort- en langtermyn) en vervoer (lug- en seevrag) gemaak word. Rabbiteye bloubessie kultivars verskil aansienlik ten opsigte van hul respirasietempo, etileenproduksie en vogverlies. Laasgenoemde kwaliteitsbepalers is by verskillende kultivars ondersoek by 15 ºC. ‘Climax’ het die hoogste respirasietempo, etileenproduksie en vogverlies getoon, terwyl ‘Premier’ die laagste respirasietempo gehad het, en die etileenproduksie te laag was om met die gaschromatograaf te bepaal. Die laagste vogverlies proporsionaliteitskonstante is waargeneem tussen ‘Tifblue’ en ‘Centurion’. ‘n Verandering is waargeneem in bloubessie vrugvleeskleur van wit tot donkerrooi by besmette bessies. ‘n Soortgelyke resultaat is verkry met kunsmatige inokulering met Botrytis cinerea. Die kleurverskil is geëvalueer deur vergelyking te tref met die antosianienpigment vlakke tussen die skil en die vlees (bepaal deur spektrofotometrie en HPLC). Antosianieninhoud van besmette vrugvlees het verdubbel, terwyl die van besmette vrugskil minder as 50 % van die kontrole groep was. Pigmentlekkasie is al vermeld by bloubessies. Dit wil voorkom of selskade veroorsaak deur infeksie beweging van antosianien vanaf die skil na die vlees kan aanhelp. Die opbergingspotensiaal van bloubessies hang af van kultivar, rypheid by oes, omgewings toestande sowel as inokulum druk. Onder gunstige toestande kan bloubessies se opbergingsvermoë effektief gemanipuleer word. Verder kultivar-spesifieke navorsing wat relevante kwaliteits kwessies aanspreek, kan gedoen word. Verder kan betroubare tegnieke in die meting van bloubessie fermheid veranderinge ondersoek word. Navorsing ten opsigte van inokulum vlakke mag insig gee in terme van bederf-druk vermindering en die gebruik van bederf-onderdrukking alternatiewe soos anti-bakteriese lappies. Skil integriteit relatief tot bederf-vatbaarheid kan ook op sellulere vlak ondersoek word.

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Made available in DSpace on 2014-06-11T19:23:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-03-30Bitstream added on 2014-06-13T20:10:16Z : No. of bitstreams: 1 gressler_e_me_rcla.pdf: 654622 bytes, checksum: d62e798a66bddcb06fc95978a87cccd8 (MD5) / São poucos os estudos que abordam a floração e frutificação em espécies filogeneticamente relacionadas. Myrtaceae é uma das famílias de plantas mais abundantes nas matas brasileiras, em especial na floresta pluvial atlântica. O presente estudo teve como objetivos principais: 1) analisar a fenologia reprodutiva de 38 espécies de Myrtaceae, verificando os padrões fenológicos, relação com os fatores climáticos e previsibilidade das fenofases; e 2) avaliar as teorias propostas para explicar a fenologia de espécies aparentadas e a relação entre a fenologia e o tamanho do fruto. O estudo foi desenvolvido em área de floresta atlântica no Parque Estadual Intervales, Base Saibadela (24°14'08S e 48°04'42W), município de Sete Barras, estado de São Paulo, Brasil. As fenofases botão, antese, fruto imaturo e maduro foram observadas mensalmente durante seis anos nãoconsecutivos (abril/1994 a março/1997 e abril/1999 a março/2002) em 285 indivíduos. As maiores porcentagens de indivíduos e espécies apresentando botões e flores abertas ocorreram sempre na estação mais quente e chuvosa (outubro a março), e produzindo frutos imaturos e maduros principalmente ao longo da estação menos quente e úmida (abril a setembro). As correlações de Spearman foram significativas entre a floração e o comprimento do dia e a temperatura, e correlações significativas foram raras entre a frutificação e o clima. A análise estatística circular mostrou que as datas de início e pico das fenofases reprodutivas em Myrtaceae foram sazonais para a maioria dos anos estudados. Todas as fenofases apresentaram valores altos de previsibilidade de ocorrência... / There are few studies approaching flower and fruit patterns among phylogenetically related species. Myrtaceae is one of the most abundant plant families in the Brazilian forests, especially in the Atlantic Rain Forest. The present study had the main objectives: 1) to analyze the reproductive phenology of 38 Myrtaceae species, checking the phenological patterns, the relationship with the climatic factors and the predictability of the phenophases; and 2) to evaluate the proposed theories to explain the phenology of related species and the relation between phenology and fruit size. The study was carried out in an Atlantic forest area at Parque Estadual Intervales, Base Saibadela (24°14'08S and 48°04'42W), municipality of Sete Barras, São Paulo State, Brazil. The phenophases bud flower, open flowers, unripe and ripe fruits were observed monthly for six nonconsecutive years (April/1994 to March/1997 and April/1999 to March/2002) in 285 individuals. The largest percentages of individuals and species presenting buds and open flowers always occurred during the wetter and hotter season (October to March), and unripe and ripe fruits were produced mainly over the less humid and colder season (April to September). The Spearman correlations were significant between flowering and the day length and the temperature, and significant correlations were rare between fruiting and climate. The circular statistical analysis showed that the first date and peak date of the reproductive phenophases in Myrtaceae were seasonal for most of the years. All the phenophases showed high predictability scores... (Complete abstract, click electronic adress below)