Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Profitability in the export driven South African blueberry industry is dependent on early spring harvests. The George region in the Western Cape accumulates too few chill-units to release buds of some southern highbush (SHB) blueberry cultivars from endodormancy. This causes problems like delayed budbreak and extended harvests. Growers of other temperate fruit crops are also affected by these problems and chemical rest breaking agents (RBAs) are applied in orchards in an attempt to overcome these. Application of the RBA hydrogen cyanamide (HC) occurs commonly in commercial pome and stone fruit orchards while thidiazuron (TDZ), another RBA is applied on a limited scale in apple orchards. The effect of RBA application on berry ripening, berry size and yield in SHB cultivars Bluecrisp, Emerald and Star was investigated for two seasons in an orchard near George, in order to determine to what extent harvest scheduling with RBAs is possible. Following Dormex® (HC, 520 g L-1) application during 2010, when a warm winter was experienced, the berry ripening of ‘Bluecrisp’ was accelerated. Dormex® application before reproductive bud scales opened, but after some chilling, resulted in acceptable yield and berry size without damage to reproductive buds. A 1% rate gave similar results as a 2% rate, but at a lower risk of reproductive bud damage. Lift® (TDZ, 3 g L-1) application reduced the number of days to 75% harvest in ‘Star’ during 2010. Lower yielding plants produced larger berries than those from higher yielding plants. Lift® application after reproductive buds scales have opened caused malformed and damaged flowers. Delaying the initiation of reproductive buds could delay spring reproductive budbreak until after new leaves had formed. In turn, this should induce a faster berry ripening rate in some SHB cultivars than would otherwise be the case following unseasonably warm winters. Reproductive bud initiation in SHB blueberries occurs under long (16 hours) nights with the mediation of phytochrome. It is possible in a controlled environment to suppress SHB blueberry reproductive bud initiation by night interruption (NI). The effect of NI on berry ripening, berry size and yield in ‘Emerald’ and ‘Snowchaser’ was investigated for two seasons, to determine what degree of harvest scheduling is possible with this technique. NI did not suppress reproductive bud development under these trial conditions, since both cultivars flowered and produced fruit. The effect on berry size and yield was cultivar specific. During 2011 NI decreased the number of berries harvested and total yield per plant in ‘Emerald’, and this decrease was linear the longer the NI lasted. / AFRIKAANSE OPSOMMING: Winsgewendheid in die uitvoer-gedrewe Suid-Afrikaanse bloubessie-bedryf is van vroeë lente oeste afhanklik. In die George-omgewing in die Wes-Kaap bou te min winterkoue op om die endodormansie van sommige ‘southern highbush’ (SHB) bloubessie kultivars natuurlik op te hef, wat probleme soos vertraagde bot en uitgerekte oestye veroorsaak. Produsente van ander gematigde vrugtesoorte, word ook deur hierdie probleme geraak en chemiese rusbreekmiddels (RBs) word in boorde aangewend in ’n poging om dit te oorkom. In kern- en steenvrugboorde vind aanwending van die RB waterstofsianamied (WS) algemeen plaas. Thidiazuron (TDZ), ’n ander RB word op beperkte skaal in appelboorde aangewend. Die uitwerking van RBs op bessierypwording, -grootte en opbrengs van SHB kultivars Bluecrisp, Emerald en Star is oor twee seisoene in ’n boord naby George ondersoek, om vas te stel tot watter mate bloubessie-oesskedulering met behulp van RB aanwending moontlik is. Na Dormex® (WS, 520 g L-1) aanwending in 2010, waarin ’n warm winter ondervind is, is die bessierypwording van ‘Bluecrisp’ versnel. Dormex® aanwendingstye voordat blomknopskubblare oopmaak, maar nadat winterkoue opgebou het, het ’n aanvaarbare opbrengs en bessiegrootte met geen blomknopskade tot gevolg gehad nie. ’n 1% Konsentrasie gee soortgelyke reaksies as ’n 2% aanwending maar teen ’n laer risiko vir blomknopskade. Lift® (TDZ, 3 g L-1) aanwending het die aantal dae tot 75% oesinsameling van ‘Star’ in 2010 verminder. Plante wat ’n laer opbrengs lewer produseer groter bessies as die wat ’n hoër opbrengs lewer. Lift® aanwending nadat blomknopskubblare oopgemaak het, het misvormde en beskadigde blomme tot gevolg gehad. Vertraging van blomknopinisiasie kan die oopmaak van blomknoppe uitstel tot na nuwe blare in die lente gevorm het. Dit kan vinniger bessie rypwording meebring as wat die geval vir sommige SHB kultivars na warm winters is. Die aanvang van blomknopontwikkeling in SHB bloubessies vind tydens lang nagte (16 ure) plaas en staan onder beheer van fitochroom. Onder beheerde toestande kan bloubessie blomknopinisiasie deur onderbreking van die lang donker (nag) tydperk (ON) in ’n lig-donker siklus onderdruk word. Die uitwerking van ON op bessierypwording, -grootte en opbrengs van ‘Emerald’ en ‘Snowchaser’ is oor twee seisoene ondersoek, om die mate waartoe oesskedulering met hierdie tegniek in ’n boord moontlik is aan te spreek. ON het nie die blomknopinisiasie onder hierdie eksperimentele toestande onderdruk nie, aangesien beide kultivars in albei seisoene kon blom en opbrengste lewer. Die effek op bessiegrootte en opbrengs was kultivar spesifiek. In 2011 is die totale opbrengs en hoeveelheid bessies per plant geoes van ‘Emerald’, deur ON verminder en dié vermindering was liniêr met toename in aantal ON siklusse.

Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Southern highbush (SHB) blueberries are relatively new to the blueberry industry and are adapted to grow in areas with low winter chilling and therefore can be grown in the Mediterranean-type climate of South Africa. The blueberry industry in South Africa is still relatively young, but it is quickly expanding and therefore appropriate cultivation practises are becoming more important. This study mainly focuses on the appropriate fertilization practises for SHB cultivars Snowchaser and Emerald grown in an ever-greening system. Plants were cultivated in plant containers in a netted tunnel in the Paarl district of South Africa. All plants received continuous fertigation with a standard commercial nutrient solution containing nitrogen, phosphorus, potassium, magnesium, calcium and all micro-elements. Carbohydrate patterns were determined on newly established tissue culture plants at two-weekly intervals from April 2013 to June 2014 and macro nutrient patterns were determined at four-weekly intervals from May 2013 to June 2014. The phenology of these plants was also visually assessed during the sampling period. Macro nutrient content was determined for two-year old „Snowchaser‟ and „Emerald‟ plants at five phenological stages during the 2013/2014 season and nutrient losses due to harvest and pruning was recorded. The phenology of evergreen „Snowchaser‟ and „Emerald‟ SHB blueberries were very different from deciduous blueberries, to such an extent that fruit could be harvested at the end of winter to early spring. Carbohydrate patterns differed between the first and the second season. Reserve carbohydrates were accumulated in the first season, but not in the second season possibly due to the difference in photosynthate production between the seasons. Plants were significantly bigger, with higher total leaf area, in the second season and it could be that carbohydrates from current photosynthesis were enough to supply new growth, thus making reserves less important. Carbohydrates could also have been used to increase flower bud development instead of being stored as reserves in the second season. Nutrient patterns also differed between the two seasons, but nutrient accumulation was apparent in the second season and not in the first. Nutrient uptake was highest when plants were growing rapidly, emphasizing the importance of fertilizer during periods of rapid growth. Huge fluctuations in the nutrient concentration patterns in the root, shoot and leaf tissues were observed over the sampling period and could have been a result of irregular fertigation and therefore it is uncertain whether flushes in nutrient uptake was a result of higher nutrient demand by the plant. Nutrients are lost due to harvest and pruning and need to be replaced by applying the right amount of fertilizer. Nutrient uptake differs throughout the season as the demand for nutrients fluctuates and therefore fertilizers should be applied at different rates during the season. In the two-year old plants, the most nutrients were accumulated after summer pruning and before growth cessation and therefore most of the fertilization would occur during this stage. Recommendations for correcting nutrient losses due to harvest and pruning are made, together with recommendations for rate and timing of fertilizer application throughout the season. / AFRIKAANSE OPSOMMING: „Southern highbush‟ (SHB) bloubessies is ‟n relatiewe nuwe ontwikkeling in die bloubessie-industrie en is aangepas om in minder koue areas aangeplant te word en daarom kan hulle in die Meditereënse-tipe klimaat van Suid-Afrika aangeplant word. Die bloubessie-industrie in Suid-Afrika is nog relatief jonk, maar dit is vinnig besig om uit te brei en daarom raak geskikte verbouingspraktyke al hoe belangriker. Hierdie studie fokus hoofsaaklik op die geskikte bemestingspraktyke vir SHB kultivars Snowchaser en Emerald wat in ‟n immergroen sisteem verbou word. Plante is in houers in ‟n tonnel, wat met net bedek is, in die Paarl distrik van Suid-Afrika, aangeplant. Alle plante het dieselfde standaard kommersiële verreikte wateroplossing, teen ‟n konstante vloei, ontvang. Die oplossing het stikstof, fosfor, kalium, magnesium, kalsium en al die mikro-elemente bevat. Koolhidraatpatrone is in twee-weeklikse intervalle, vanaf April 2013 tot Junie 2014, vir nuut gevestigde weefselkultuurplante bepaal en makro-element patrone is in vier-weeklikse intervalle, vanaf Mei 2013 tot Junie 2014, bepaal. Die fenologie van dié plante is visueel waargeneem tydens die monsternemingsperiode. Makro-elementinhoud is vir tweejarige „Snowchaser‟ en „Emerald‟ plante by vyf fenologiese stadiums tydens die 2013/2014 seisoen bepaal en die voedingstofverliese as gevolg van oes en snoei is bepaal. Die fenologie van immergroen „Snowchaser‟ en „Emerald‟ SHB bloubessies het opmerklik verskil van bladwisselende bloubessies, tot so ‟n mate dat vrugte al teen einde winter na vroeë lente geoes kon word. Koolhidraatpatrone van die eerste en tweede seisoen het verskil deurdat reserwe koolhidrate in die eerste seisoen opgebou het, maar nie in die tweede seisoen nie, moontlik as gevolg van die verskil in fotosintaatproduksie tussen die twee seisoene. Plante was opmerklik groter, met groter blaaroppervlak, in die tweede seisoen en dit kon wees dat koolhidrate van huidige fotosintese genoeg was om die groei te onderhou en sodoende die afhanklikheid van reserwes te verminder. Koolhidrate kon ook vir verhoogde blomknopontwikkeling gebruik geword het, in plaas van om as reserwes vir die tweede seisoen gestoor te word. Voedingstofpatrone het ook tussen seisoene verskil, maar voedingstofakkumulasie was duidelik in die tweede seisoen en nie in die eerste nie. Voedingstofopname was die hoogste wanneer plante vinnig gegroei het en daarom is bemesting tydens periodes van vinnige groei uiters belangrik. Groot wisselinge in die voedingstofkonsentrasiepatrone van die wortels, lote en blare is tydens die monsternemingsperiode waargeneem en onreëlmatige verrykte watertoediening kon dit veroorsaak het. Daarom is dit onseker of fluktuasies in voedingstofopname ‟n gevolg was van hoër voedingstofaanvraag deur die plant. Voedingstowwe gaan verlore deur oes en snoei en moet deur die toediening van korrekte bemesting vervang word. Voedingstofopname verskil oor die verloop van die seisoen soos die aanvraag vir voedingstowwe deur die plant verander en daarom moet bemestingstowwe teen verskillende hoeveelhede deur die seisoen toegedien word. In die tweejarige plante is meeste van die voedingstowwe ná somersnoei en voor groeistaking opgeneem en daarom moet meeste van die bemesting tydens hierdie stadium toegedien word. Aanbevelings vir die korrigering van voedingstofverliese as gevolg van oes en snoei, tesame met aanbevelings vir die hoeveelheid en tyd van bemestingstoediening deur die seisoen, word gemaak.

Made available in DSpace on 2014-08-20T13:25:42Z (GMT). No. of bitstreams: 1 Tese_Nara_Cristina_Ristow.pdf: 1070166 bytes, checksum: b4c300a1528b3846038c18df172a3e8b (MD5) Previous issue date: 2009-07-10 / Blueberry is a temperate fruit species climate, cultivated in Europe, in the United State and Canada, where it has a great economic importance. Its cultivation has driven to a significant expansion in the last years, due to the fruit nutritional characteristics. Blueberries are rich in vitamins and minerals, low calorie and have high antioxidant concentration, establishing a demanding market in healthy foods. The supply of uniform plants with high quality and the development of an efficient and competitive production system added to marketing strategies are among the technologies to be adapted. The objectives of this work were: (i) to determine a suitable substrate to vegetative propagation by microcutting technique and blueberry plant growth; (ii) validate the technique of microcutting; (iii) to evaluate rooting and surviving capacity of blueberry microcuttings. Different experiments were done to achieve the objectives. It was evaluated growth of in vitro-originated plant of cultivar Georgiagem in different substrates. The microcuttings were kept under moist micro-environment conditions at both regulated temperature and light. It was evaluated the blueberry microcutting technique to the cultivars Georgiagem, O‟Neal and Misty under moist micro-environment method, two microcuttings collection period and two IBA concentrations. Was evaluated plant surviving of the cultivars Georgiagem and O‟Neal. Also, it was verified rooting potential of blueberry microcutting treated with different concentrations of indolbutiric acid (IBA) in powder formulation. It was concluded that the substrates such as pinus needle + soil and plantmax®, followed by plantmax® + perlite and rice rull + soil promoted better blueberry plant development of the cv. Georgiagem. The substrates sphagnum peat moss and the mixes of peat + perlite, peat + perlite + coconut fiber and peat + perlite + sawdust allowed higher rooting percentage. The results referent to microcutting rooting, showing high levels of rooting for the cultivars Misty, O'Neal and Georgiagem. The plant surviving of blueberry cultivars O‟Neal and Georgiagem propagated by microcutting method was superior to 90%. The application of 4000 mg/kg of IBA promoted the best rooting rates and root volume of blueberry microcuttings cultivar Climax, showing rooting percentage of 91,67. / O mirtileiro é uma espécie frutífera de clima temperado, cultivada na Europa, nos Estados Unidos e Canadá, onde tem grande importância econômica. Seu cultivo tem apresentado grande expansão nos últimos anos, devido às características nutricionais do fruto, que é rico em vitaminas e minerais, possui baixas calorias e uma alta concentração de antioxidantes, determinando a demanda do mercado exigente em alimentos saudáveis. A oferta de mudas uniformes e de qualidade e desenvolvimento de sistema de produção eficiente e competitivo, aliado a estratégias de marketing , estão dentre as medidas a serem adotadas para o aumento da área cultivada. Assim, os objetivos deste trabalho foram: (i) definir um substrato adequado para a propagação vegetativa através da técnica de microestaquia e para o crescimento de mudas de mirtileiro; (ii) validar a técnica de microestaquia; (iii) avaliar a capacidade de enraizamento e sobrevivência de microestacas de mirtileiro. Para atingir os objetivos, foram realizados diferentes trabalhos. Avaliou-se o crescimento de mudas de mirtileiro, cultivar Georgiagem, oriundas de multiplicação in vitro em diferentes substratos. Da mesma forma, foram avaliados diferentes substratos para a técnica de microestaquia mantidas em condições de micro-ambiente úmido com temperatura e luz controlada. Foi avaliada a técnica de microestaquia para cultivares de mirtileiro do grupo southern highbush em dois períodos de coletas, sob micro-ambiente úmido, e a sobrevivência de mudas, obtidas através desta técnica. Foi verificado o efeito do AIB no enraizamento de microestacas de mirtileiro grupo rabbiteye da cultivar Clímax. Nas condições em que foram realizados os trabalhos, conclui-se que: Os substratos acícula de pinus + solo e plantmax®, seguido pelos substratos plantmax® + perlita e casca de arroz + solo, promoveram maior desenvolvimento das mudas de mirtilo, cultivar Georgiagem. Os substratos testados turfa de musgo sphagnum e as misturas turfa + perlita, turfa + perlita + fibra de coco, turfa + perlita + serragem, permitiram a obtenção de um maior percentual de enraizamento. Os resultados referentes ao enraizamento de microestacas, mostraram-se eficiente, apresentando elevados índices de enraizamento para as cultivares Misty, O‟Neal e Georgiagem. A sobrevivência das mudas de mirtileiro cultivares O‟Neal e Georgiagem, propagadas pelo método de microestaquia foram superiores a 90%. A aplicação de 4.000 mg kg-1 de AIB proporcionou os melhores índices de enraizamento e crescimento radicular de microestacas de mirtileiro cultivar Climax, com percentuais de enraizamento de 91,67%.

Seediness and other differences between rabbiteye-RB (Vaccinium ashei), southern highbush-SHB (Vaccinium darrowii), and commercial market equivalent, highbush-HB (Vaccinium corymbosum) varieties/lines were determined. Forty six selections of rabbiteye and southern highbush blueberries, and three highbush varieties, were analyzed for seediness (seeds per berry volume, SPV). There were no differences (p > 0.05) in SPV between SHB and RB selections, but differences (p < 0.05) existed within species. Berries were assigned to 8 groups based on SPV to conduct sensory panels and chemical analysis. Consumers perceived RB more different than SHB from HB blueberries. In the descriptive panel, differences (p < 0.05) were found in shriveling, skin intactness, grittiness, seediness, and tartness. The soluble solids to acid ratio of HB, SHB, and RB averaged 16.05, 9.60, and 11.05%, respectively. Some consumers and trained panelists can discern differences due to seediness and other traits between blueberry species.