Dissertation (PhD(Agric))--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Advancement of the flowering time of Protea cv. Carnival by approximately three months, without compromising the product quality, was achieved by the application of 6- benzyladenine-containing plant growth regulators to three-flush shoots in autumn. This earlier flowering time coincides favourably with the prime European marketing period (November-January). The percentage three-flush shoots initiating an inflorescence following the brush application of the 6-benzyladenine (BA)-containing regulators, ABG- 3062 (active ingredient: BA 2% w/w) and Accel® (active ingredients: BA 1.8% w/w; gibberellins A4A7 0.18% w/w) on dormant terminal buds, increased with later application dates and flowering percentages as high as 90% was achieved. No inflorescences were initiated on flushes induced by Promalin® (active ingredients: BA 1.8% w/w; gibberellins A4A7 1.8% w/w). Phenological phase progression of green point, flush expansion and inflorescence development of 'Carnival' shoots as induced by BA was calculated to have base temperatures of 8°C, 6°C and 1°C respectively. The days required from application of the BA-containing growth regulator until green point stage increased progressively over the six consecutive treatment dates in autumn (14 March - 22 May 2003). In contrast, the days required to complete inflorescence development decreased with each successive treatment date. The days required between the respective stages were mostly negatively correlated with temperature, except for the phase 'green point to flush expansion', where the relationship was unclear. For three-flush shoots of eight-year old plants, between 13-57, 39-65 and 121-177 days were required to reach green point, to achieve full flush expansion following green point and to complete inflorescence after flush expansion respectively. BA application enhanced budbreak in most dormant shoots, irrespective of plant age, BA concentration, decreasing temperature over time or shoot characteristics. However, twoflush shoots treated in late May had low budbreak and hence low flowering percentages. Shoots varied considerably in their responsiveness to BA treatments. BA application (500mg·L-1) as MaxCelTM (active ingredients: BA 1.9% w/w) to terminal buds alone of mature three-flush shoots from less vigorous growing plants resulted in the highest flowering percentages. Applications were most effective when applied to the terminal bud in the dormant state or up to the ‘green point’ stage. Shoot characteristics such as flush length, leaf area, shoot dry mass, number and proximity of the leaves to the terminal bud were all positively correlated with the propensity of shoots to initiate inflorescence under BA induction. Terminal flush intercalation shoot diameter (>7mm) was identified as the most important variable influencing the likeliness of flowering and can effectively serve as a nondestructive estimation of a shoot's propensity to flower. The presence of developing inflorescences or possible floral inhibiting factors derived from the previous flowering season is suggested to be inhibitory to inflorescence initiation following BA application. Synchronisation of shoot growth by pruning plants in late winter appears to be an essential step to ensure high percentages inflorescence initiation with BA treatment the following autumn. The use of BA as a management tool to control flowering times in Protea for better market opportunities is shown to hold considerable commercial potential. / AFRIKAANSE OPSOMMING: Protea cv. Carnival se blomtyd is met ongeveer drie maande vervroeg sonder om produkkwaliteit prys te gee. Hierdie vervroegde blomtyd wat gunstig saam val met die optimale Europese bemarkingstyd van November-Januarie is bewerkstelling deur die herfstoediening van 6-bensieladenien-bevattende plantgroei-reguleerders op lote bestaande uit drie groeistuwings. Die persentasie lote met drie groeistuwings wat 'n bloeiwyse geïniseer het na 'n kwas-aanwending met die 6-bensieladenien (BA)-bevattende groeireguleerders, ABG-3062 (aktiewe bestandeel: BA 2% w/w) en Accel® (aktiewe bestandele: BA 1.8% w/w; gibberellins A4A7 0.18% w/w), het toegeneem met latere behandelingsdatums en blompersentasies so hoog as 90% is behaal. Geen bloeiwyses is geïnisieer op groeistuwings wat deur Promalin® (aktiewe bestandeel: BA 1.8% w/w; gibberellins A4A7 1.8% w/w) teweeggebring is nie. Basis temperature van 8°C, 6°C en 1°C respektiewelik is bereken vir fenologiese fasevordering vanaf groeireguleerder toediening tot by groenpunt, groeistuwing-voltooing en bloeiwyse-ontwikkeling van 'Carnival' lote soos geïnduseer deur BA. Die dae wat benodig was vanaf toediening van die BA-toediening totdat groenpunt stadium bereik is, het progressief toegeneem oor die ses opeenvolgende herfsbehandelingsdatums (14 Maart-22 Mei 2003). In teenstelling met bostaande, het die vereiste aantal dae om bloeiwyseontwikkeling te voltooi afgeneem met elke opeenvolgende behandelingsdatum. Die aantal dae wat benodig was vir die onderskeie fases was meestal negatief gekorreleer met temperatuur, behalwe vir die fase 'groenpunt tot groeistuwing-voltooing', waar die verhouding onduidelik was. Vir lote van agt-jaar-oue plante met drie groeistuwings was tussen 13-57, 39-65 en 121-177 dae respektiewelik benodig om groenpunt te bereik, volledige groeistuwingverlenging te bewerkstellig en om bloeiwyse-ontwikkeling wat volg na groeistuwing verlenging, te voltooi. BA-toediening het knoprusbreking bevorder in die meeste dormante lote, ongeag plant ouderdom, BA konsentrasie, afname in temperatuur met tyd of loot eienskappe. Lote met twee groeistuwings wat laat in die herfs behandel is, het egter lae rusbreking en dus gevolglik ook lae blompersentasies getoon. Lote varieer aansienlik in hul reaksie op BA behandeling. BA toediening (500mg·L-1) as MaxCelTM (active ingredients: BA 1.9% w/w) op die terminale knop van afgeharde lote met drie groeistuwings en afkomstig van minder groeikragtige plante het tot die hoogste blompersentasies gelei. Die effektiwiteit van die behandeling was die hoogste met toedienings aan dormante terminale knoppe tot en met groenpuntstadium. Loot eienskappe soos groeistuwinglengte, blaaroppervlakte, loot droë massa, asook die aantal en nabyheid van die blare relatief tot die terminal knop was almal positief gekorreleerd met die vermoë van die loot om 'n blom te inisisieer in reaksie op BA induksie. Terminale groeiverstuwing interkalasie-lootdikte (>7mm) is geïdentifiseer as die belangrikste veranderlike wat die vermoë om te kan blom kan beïnvloed en kan gebruik word as 'n nie-destruktiewe voorspeller vir blom-inisiasie. Die teenwoordigheid van ontwikkelende bloeiwyses of potensiële blom-inhiberende faktore aanwesig in die loot na die vorige blomperiode, word moontlik beskou om inhiberend te wees vir BA-geïnduseerde blom-inisiasie. Sinchronisering van lootgroei deur die snoei van plante in laat-winter blyk krities te wees om 'n hoë blompersentasie met BA behandeling te verseker in die daaropvolgende herfs. Die aanwending van BA as 'n bestuurstegniek om die blomtyd van Protea te posisioneer vir beter bemarkingsgeleenthede toon aansienlike kommersiële potensiaal.

Master of Science / Department of Horticulture, Forestry, and Recreation Resources / Kimberly A. Williams / Liquid organic fertilizers and microbial inoculants of beneficial microorganisms are garnering interest from commercial greenhouse growers who seek to produce crops more sustainably, but research about their efficacy is limited and results are conflicting. This research focused on comparing the effect of microbial inoculant addition in two soilless crop production systems under organic versus conventional fertilization. Two experiments were conducted with impatiens (Impatiens walleriana) in a peat-based substrate and four experiments were conducted with butterhead lettuce (Latuca sativa) in nutrient film technique (NFT) hydroponics. In the impatiens studies, nitrogen, phosphorus, and potassium were incorporated pre-plant equally across treatments using OsmocoteTM, or organic fertilizers Bloodmeal or Feathermeal. An inorganic constant liquid feed (CLF) was also evaluated. Microbial inoculants that contained a variety of beneficial species, including Bacillus spp. and Trichoderma spp. were drench-applied at the beginning of the cropping cycle. Impatiens growth was comparable between the nutrient regimens in one of the studies. CO2 respiration was measured on substrate samples. At a 5X application rate, inoculants contributed to subtle increases in plant growth in organic treatments, but microbial activity was unaffected as measured by CO2 respiration. However, organic nutrient sources contributed to higher CO2 respiration at day 7 of the production cycle compared to inorganic nutrient sources. The hydroponic trials consisted of inorganic and organic nutrient regimens, evaluated with and without microbial inoculant addition. Nutrient analyses and CO2 respiration of the nutrient solutions were collected. Use of inoculants resulted in increased plant growth when used in organic nutrient regimens in some trials. Plant dry weight and CO2 respiration in the inorganic nutrient regimens were increased in certain instances with inoculant addition. No differences in mycorrhizal root colonization were observed in either nutrient regimen with mycorrhizal inoculant addition. Petiole NO3-N concentration of lettuce plants grown with inorganic nutrient sources was greater than that of plants in organic regimens. Organic fertilizers and inoculant products resulted in comparable or positive impacts on plant growth and food crop quality in some treatment scenarios in these studies. The specific circumstances of crop production systems dictate whether plant growth response may occur from inoculant incorporation.

Thesis (M. Arch.)--University of Hong Kong, 1997. / Includes special report study entitled: Light-and-space in earth architecture. Includes bibliographical references.

Thesis (M.Arch.)--University of Hong Kong, 1997. / Includes special report study entitled : Light-and-space in earth architecture. Includes bibliographical references. Also available in print.

Thesis (MScAgric)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Commercial production of the southern highbush blueberries (SHB) ‘Jewel’, ‘Emerald’, ‘Star’, ‘Snowchaser’ and ‘Bluecrisp’ started recently in the Western Cape. In South Africa, no research has been conducted on pruning and pollination of SHB, and various questions regarding these practices have arisen. Six experiments were conducted to evaluate the self-compatibility and the effect of cross-pollination on berry characteristics of ‘Star’, ‘Emerald’, ‘Jewel’, ‘Bluecrisp’ and ‘Snowchaser’. The effect of cross-pollination on fruit set, berry weight, berry diameter and fruit development period is cultivar dependant. ‘Bluecrisp’ appears self-incompatible and ‘Misty’ or ‘Emerald’ can be recommended as cross-pollinators. ‘Snowchaser’ seems self-compatible and solid block plantings can be recommended. ‘Misty’ and ‘Emerald’ would be recommended as cross-pollinators for ‘Star’ and ‘Jewel’ respectively, even though these cultivars will set an adequate crop when self-pollinated. Although ‘Emerald’ seem self-compatible, the fruit set tends to vary greatly and cross-pollination with ‘Jewel’, ‘Misty’ and ‘Bluecrisp’ is recommended to obtain early maturing berries of the required size. Another season’s data is required before final conclusions can be drawn. In order to establish sustainable summer pruning strategies for South African growing conditions that will maximise yield and berry quality for SHB, two pruning trials were conducted. In the first trial, the severity of pruning of ‘Star’, ‘Emerald’ and ‘Jewel’ was evaluated. We established that summer pruning is a compromise between total yield and desired berry size. All the pruning treatments reduced total vegetative growth and shoot number, but increased individual shoot length. Summer pruning increased berry weight and diameter by reducing total yield, but also by developing better quality bearing wood. Vigorous laterals stimulated by pruning seize growth later thereby delaying reproductive bud initiation and harvest. An increase in the severity of pruning increased the level to which the plants responded. No pruning and ‘light pruning’ gave the highest yields, but one more season’s data will clarify whether successive light pruning is sustainable. “Standard pruning” resulted in a well-balanced plant with an intermediate yield and berry size. Heading of one-year-shoots as part of the pruning strategy is not recommended for any of the cultivars. “Severe pruning” will only be recommended for young, newly established plantings where vegetative growth is the main objective. A second trial was conducted to study the effect of time of summer pruning. At Teeland, delaying pruning resulted in a decrease in total new growth and shoot number thereby reducing yield. This was probably due to progressively more buds that became endodormant. For all three cultivars, pruning as soon as possible after harvest would therefore be recommended. At Lushof, the effect of time of summer pruning was not significant. This could be due to the fact that plants were younger and more vigorous or because the area is warmer and growth continued for longer. One more season’s data is needed before any final conclusions are drawn. / AFRIKAANSE OPSOMMING: Kommersiële verbouing van die “southern highbush” bloubessies (SHB) ‘Jewel’, ‘Emerald’, ‘Star’, ‘Snowchaser’ en ‘Bluecrisp’ is ’n nuwe ontwikkeling in die Wes-Kaap. In Suid-Afrika is nog geen navorsing oor die snoei en bestuiwing van SHB onderneem nie, en verskeie vrae het oor hierdie praktyke ontstaan. Ses eksperimente is gedoen om die self-verenigbaarheid, sowel as die effek van kruisbestuiwing op bessie-eienskappe van ‘Star’, ‘Emerald’, ‘Jewel’, ‘Bluecrisp’ en ‘Snowchaser’ te evalueer. Die effek van kruisbestuiwing op vrugset, bessiegewig, bessiedeursnee en vrugontwikkelingsperiode is kultivar spesifiek. ‘Bluecrisp’ blyk self-onverenigbaar te wees en kruisbestuiwing met ‘Misty’ of ‘Emerald’ word aanbeveel. ‘Snowchaser’ blyk self-verenigbaar te wees en suiwer blok aanplantings kan dus aanbeveel word. ‘Misty’ en ‘Emerald’ word onderskeidelik as kruisbestuiwers vir ‘Star’ en ‘Jewel’ aanbeveel, alhoewel beide kultivars ‘n goeie oes sonder kruisbestuiwing kan lewer. Vir ‘Emerald sal kruisbestuiwing met ‘Jewel’, ‘Misty’ of ‘Bluecrisp’ aanbeveel word, indien vroeë, groot bessies belangrik is. ’n Tweede seisoen se data word benodig om bogenoemde te bevestig voor finale aanbevelings gemaak kan word. Twee snoeiproewe is uitgevoer om volhoubare somersnoei-strategieë te ontwikkel wat die opbrengs en kwaliteit van bessies onder Suid-Afrikaanse groeitoestande sal maksimeer. In die eerste snoeiproef is die intensiteit van snoeisnitte vir ‘Star’, ‘Emerald’ en ‘Jewel’ ondersoek. Daar is vasgestel dat totale opbrengs en bessiegrootte teen mekaar opgeweeg moet word wanneer strafheid van snoei ge-evalueer word. Somersnoei verminder totale vegetatiewe groei en aantal nuwe lote, maar vermeerder lootlengte en bessiegrootte. Somersnoei het ‘n toename in bessiegrootte tot gevolg deur dat die totale opbrengs verminder, maar ook deur die kwaliteit van draende lote te verbeter. Meer groeikragtige lote gestimuleer deur somersnoei, staak verlengingsgroei later in die seisoen wat dan lei tot later bloknopinisiasie en oes. Geen snoei, sowel as “ligte snoei” het gelei tot die grootste opbrengs na die afloop van een seisoen, maar nog ‘n seisoen se data word benodig om vas te stel of dit volhoubaar is. “Standaard snoei’” lei tot ‘n goed gebalanseerde plant met ‘n gemiddelde opbrengs en bessiegrootte. “Harde snoei” sal slegs aanbeveel word vir nuwe aanplantings waar vegetatiewe groei die hoof prioriteit is. Om die tydsbereking van somersnoei aan te spreek, is ‘n tweede snoeiproef uitgevoer. Op Teeland, het ‘n uitstel van somersnoei gelei tot ‘n afname in vegetatiewe groei en aantal lote en dit het dan gelei tot ‘n afname in opbrengs. Hierdie was moontlik die gevolg van meer knoppe wat mettertyd in endodormansie ingegaan het. Op Lushof het die tydsberekening van somersnoei geen betekenisvolle effek gehad nie. Dit kan moontlik toegeskryf word aan die jonger, groeikragtige plante, of aan die langer groeiseisoen weens die warmer klimaat in die area. Nog ‘n seisoen se data word egter benodig voor enige finale gevolgtrekkings gemaak kan word.

Thesis (MScAgric (Horticulture))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The size of the navel-end opening is an important parameter for external fruit quality in navel oranges [Citrus sinensis (L.) Osbeck]. The application of 2,4-dichlorophenoxyacetic acid (2,4-D) to increase the percentage of closed navel-ends and reduce the size of the navel-end opening was conducted on six different navel orange cultivars. Treatments were applied at full bloom (FB), 100% petal drop (PD), as well as 2 weeks (2 WAPD) and 4 weeks after 100% petal drop (4 WAPD), at 15 mg·L-1 to 45 mg·L-1, to determine the most effective timing and concentration. The application of 2,4-D at FB consistently decreased the average navel-end size (all fruit) and increased the percentage of closed navel-ends in all the cultivars, with later applications at PD, 2 WAPD and 4 WAPD being generally ineffective, regardless of the concentration applied. There were no major negative side effects on internal and external fruit quality, except for the reduction in juice content (%), especially with the later treatments. Therefore, 15 mg·L-1 2,4-D at FB can be applied to increase the percentage of closed navel-ends and possibly increase export packouts. Navel oranges have a small secondary fruit located inside the primary fruit at the stylar-end and an opening at the stylar-end called the navel-end opening or the stylar-end aperture. Fruit growth and development was studied in three navel orange cultivars by measuring the primary fruit diameter, the secondary fruit diameter and the navel-end opening fortnightly, using both destructive and non-destructive sampling methods. The relationships between the primary fruit size, the secondary fruit size and the navel-end opening size were studied using correlation analysis. In addition, the effect of 2,4-D on fruit morphology, when applied as a treatment to reduce the size of the navel-end opening, was also evaluated on the same cultivars. The primary fruit, the secondary fruit and the navel-end opening followed a similar developmental pattern, although the navel-end opening developed later, about six weeks after FB. The primary fruit size was not related to the size of the secondary fruit or the navel-end opening. Similarly, the size of the navel-end opening was not related to the size of the secondary fruit. No negative effects were noted on the primary fruit morphology when 2,4-D was applied. Fruit splitting is a major physiological disorder of ‘Marisol’ Clementine mandarin (Citrus reticulata) fruit. The effect of application of 2,4-D on fruit splitting and fruit quality was evaluated on ‘Marisol’ Clementine mandarin trees grafted on Troyer citrange rootstock. Treatments included an untreated control, 2,4-D applied at 15 mg·L-1 or 25 mg·L-1 at FB and 15 mg·L-1 or 25 mg·L-1 at PD. The application of 2,4-D reduced fruit splitting in ‘Marisol’ Clementine fruit. Internal fruit quality was not affected by the treatments, however, the fruit developed a coarse rind due to enlarged oil glands and the styles stayed attached on the fruit until harvest. Therefore, although 2,4-D reduced fruit splitting, it cannot be recommended at the timings and concentrations evaluated. / AFRIKAANSE OPSOMMING: Die grootte van die nawel-ent opening is ‘n belangrike parameter vir eksterne vrugkwaliteit van nawel lemoene [Citrus sinensis (L.) Osbeck]. Die toediening van 2,4-dichlorofenoksie asynsuur (2,4-D) om die persentasie geslote nawel-ente te vermeerder en die grootte van die nawel-ent opening te verklein is uitgevoer op ses verskillende nawel lemoen kultivars. Behandelings is toegedien by volblom (FB), 100% blomblaarval (PD), asook 2 weke (2WAPD) en 4 weke na 100% blomblaarval (4 WAPD), teen 15 mg·L-1 tot 45 mg·L-1, om die mees effektiewe tyd van toediening en konsentrasie te bepaal. Die toediening van 2,4-D by FB het herhaaldelik die gemiddelde nawel-ent grootte (alle vrugte) verminder en die persentasie geslote nawel-ente vermeerder in al die kultivars, terwyl die later toediening by PD, 2 WAPD en 4 WAPD oor die algemeen nie effektief was nie, ongeag die konsentrasie toegedien. Daar was geen noemenswaardige negatiewe effekte op interne en eksterne vrugkwaliteit nie, behalwe vir ‘n verlaging in die sapinhoud (%) van vrugte, veral by die later behandelings. Dus kan 15 mg·L-1 2,4-D by FB toegedien word om die persentasie geslote nawel-ente te vermeerder en moontlik ook die uitvoerpersentasie te verhoog. Nawel lemoene het ‘n klein sekondêre vrug binne die primêre vrug aan die styl-ent en ‘n opening by die styl-ent wat die nawel-ent opening of die styl-ent opening genoem word. Die vruggroei en ontwikkeling van drie nawel kultivars is bestudeer deur die primêre en sekondêre vrugdeursnit en die nawel-ent opening elke twee weke te meet, deur gebruik te maak van destruktiewe en niedestruktiewe monsterneming. Die effek van 2,4-D op vrugmorfologie, toegedien as ‘n behandeling om die nawel-ent grootte te verklein, is ook ge-evalueer op dieselfde kultivars. Die primêre vrug, die sekondêre vrug en die nawel-ent opening het dieselfde ontwikkelingspatroon gevolg, alhoewel die nawel-ent opening later ontwikkel het. Daar was geen sterk verwantskap tussen die primêre vruggrootte en die sekondêre vruggrootte of die grootte van die nawel-ent opening nie. Daar was ook nie ‘n vewantskap tussen die grootte van die nawel-ent opening en die sekondêre vruggrootte nie. Geen negatiewe effekte op vrugmorfologie as gevolg van die 2,4-D toediening is waargeneem nie. Vrugsplit is ‘n belangrike fisiologiese abnormaliteit van ‘Marisol’ Clementine (Citrus reticulata) vrugte. Die effek van 2,4-D op vrugsplit en vrugkwaliteit is ge-evalueer op ‘Marisol’ Clementine mandaryn bome op Troyer citrange onderstamme. Die behandelings het ‘n onbehandelde kontrole, 2,4-D toegedien teen 15 mg·L-1 of 25 mg·L-1 by FB en 15 mg·L-1 of 25 mg·L-1 by PD ingesluit. Die toediening van 2,4-D het vrugsplit verminder. Interne vrugkwaliteit was nie geaffekteeer deur die behandelings nie, maar die vrugte het ‘n growwe skil ontwikkel as gevolg van vergrote oliekliere en die style het aangeheg gebly aan die vrugte tot oestyd. Dus, alhoewel 2,4-D vrugsplit verminder het, kan dit nie aanbeveel word teen die tyd van toediening en konsentrasie soos ge-evalueer in hierdie studie nie.

Thesis (MScAgric)--Stellenbosch University, 1963. / ENGLISH ABSTRACT: no abstract available / AFRIKAANSE OPSOMMING: geen opsomming

Thesis (MScAgric)--Stellenbosch University, 1969. / ENGLISH ABSTRACT: no abstract available / AFRIKAANSE OPSOMMING: geen opsomming

Thesis (MScAgric)--Stellenbosch University, 1962. / ENGLISH ABSTRACT: no abstract available / AFRIKAANSE OPSOMMING: geen opsomming

Thesis (MScAgr)--Stellenbosch University, 1962. / ENGLISH ABSTRACT: no abstract available / AFRIKAANSE OPSOMMING: geen opsomming