Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Little research has been done on natural feed additives which enhance milk production in dairy animals. Fenugreek (Trigonella foenumgraecum) is a member of the legume family and is found in India, Middle East, North Africa and South Europe. Fenugreek is used as an herb in traditional medicine to promote lactation in lactating women. It also influences the lactation performance in ruminants such as dairy cows, water buffaloes and dairy goats. Diocin is a natural saponin found in Fenugreek and has structural similarity to oestrogen, which leads to an increased release of growth hormone (GH) and ultimately milk production. Three different trials were carried out to investigate Fenugreek’s effects. Each trial consisted of three treatment groups where dairy goats were randomly assigned. Nutrifen®, NutrifenPlus® and a control treatment served as the three treatments used in this study. Forty-eight goats per treatment group were used in the first trial where the main objective was to evaluate Fenugreek’s effect on milk production and milk composition. The second trial consisted of eight goats per treatment group, where Fenugreek’s effect on the in vivo and in vitro digestibility of the feed served as the main objective of this study. In the final part of the study, growth hormone found in plasma was subsequently investigated using the same goats from trial two. Fenugreek’s effect on elevating GH levels was the objective from the third part of the study. The first trial showed promising results in terms of an increase in milk production (P = 0.01) from dairy goats using the Nutrifen® treatment and an increase in milk lactose (P = 0.03) using the NutrifenPlus® treatment. Blood cholesterol and cholesterol content found in the milk did not differ between treatments used. Apparent digestibility of the total digestible nutrients (TDN) from the feed did not increase and did not differ between treatments and therefore concluded that the dairy goats digested the different treatments with similar efficiency regardless of the additive added to the feed. Growth hormone levels found in plasma also did not differ between treatments used in the third part of the study. Variation was found in GH plasma levels and this was expected as GH levels are known to have variation within ruminants. It appears that Fenugreek used as a natural feed additive can increase the milk yield from dairy goats, which would be beneficial to the commercial dairy goat farmer. However, the process on how Fenugreek exerts its effect on milk production still remains unclear. / AFRIKAANSE OPSOMMING: Tot datum is min navorsing gepubliseer wat die invloed van natuurlike voer bymiddels op melkproduksie aanspreek. Fenugreek (Trigonella foenumgraecum) is ‘n peulgewas en kom voor in Indië, die Midde Ooste, Noord Afrika en Suid Europa. Fenugreek word in tradisionele medisyne gebruik om sodoende melkproduksie in lakterende vroue te verhoog. Dit verhoog ook melkprodukise in melkkoeie, waterbuffels en melkbokke. Diocin is ‘n natuurlike saponien, met sterk oestrogeniese strukturele ooreenkomste, wat in Fenugreek voorkom. Diocin lei tot die verhoogde afskeiding van groeihormoon (GH) en uiteindelik ‘n toename in melkproduksie. Drie proewe is uitgevoer ten einde die effek van Fenugreek te ondersoek. Elke proef het bestaan uit drie behandelingsgroepe en melkbokke is ewekansig aan die groepe toegedeel. Nutrifen®, NutrifenPlus® en ‘n kontrole sonder enige additief is gebruik as behandelings. Agt-en-veertig bokke is per behandeling gebruik in die eerste proef. Die doel van hierdie proef was om die invloed van Fenugreek op melkproduksie en melksamestelling te bepaal. Die tweede proef het agt bokke per behandelingsgroep gehad en het ten doel gehad om te bepaal wat die invloed van Fenugreek op die in vitro en in vivo verteerbaarheid van die voere was. In die derde proef is dieselfde bokke as die in proef twee gebruik en hier is groeihormoon vlakke in sirkulerende bloedplasma gemeet om die invloed van Fenugreek op hierdie parameter te bepaal. Resultate van die eerste proef het getoon dat melkproduksie van bokke wat Nutrifen® ontvang het betekenisvol verhoog het (P = 0.01) terwyl NutrifenPlus® gelei het tot ‘n verhoging (P = 0.03) in melk laktose vlakke. Bloed cholesterol en melk cholesterol vlakke was onveranderd. Skynbare verteerbaarheid van die totale verteerbare voedingstowwe (TVV) van die voer het nie verander (P = 0.34) met die insluiting van Fenugreek nie. Plasma groeihormoonvlakke was nie betekenisvol verskillend (P > 0.05) tussen behandelingsgroepe nie en die gebrek aan verskille kan waarskynlik toegeskryf word aan die variasie wat binne behandelings groepe opgemerk is vir hierdie parameter. Sodanige variasie in plasma groeihormoon word as algemeen beskou in herkouers. Gevolglik kan aanvaar word dat die natuurlike voerbymiddel, Fenugreek, gebruik kan word om melkproduksie in lakterende melkbokke te verhoog. Hierdie praktyk behoort voordele in te hou vir die kommersiële melkprodusent. Die proses waardeur hierdie verhoging plaasvind is egter steeds nie duidelik nie.

Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Paraffin, also called kerosene is used by small-scale soya bean farmers in some parts of Africa as a pest repellent. The repellent action is claimed to be effective against parasites during seed germination and development of the seedlings. Seeds are immersed in commercial paraffin for a few seconds and sown in the soil immediately. This method raised some questions about possible negative effects on the seed after the imbibition process but also on humans and animals consuming the plants and seeds. Experiments were designed to investigate whether this practice would have negative effects on seed germination and vigour of the resulting seedlings of seven selected crop species. A trial was also carried out to test the effectiveness of paraffin as a pest repellent on canola in a field situation. The collected data were analyzed using STATISTICA, software version 11. Wherever the experiments showed significant interaction or differences within main factors, the means were separated making use of Fischer’s LSD post-hoc analysis at p = 0.05. The first series of experiments was done in the laboratory. It was carried out on seeds of seven crop species: canola (Brassica napus L.), common beans (Phaseolus vulgaris L.), ground nuts (Arachis hypogea L.), maize (Zea mays L.), soya bean (Glycine max L.), sunflower (Helianthus annuus L.) and wheat (Triticum aestivum L.). In the germination trial, seeds were subjected to a 7X5X4 factorial design treatment with factors Crop species (CS) (see above), Paraffin concentration (PC) (0, 25, 50, 75 and 100% of commercial paraffin diluted with distilled water) and Time of immersion (TOI) (1, 5, 10, and 30 minutes). Treatments were repeated four times. After immersion seeds were dried with water absorbent paper and immediately germinated in 90 mm diameter petri dishes containing two filter papers and 5 ml of distilled water. Germination tests included 10 seeds per replicate and were incubated at a constant temperature of 20°C under dark conditions in an incubator. Findings showed that canola, sunflower and soya bean are paraffin tolerant (>70 % germination), wheat and groundnuts are less tolerant (30% – 70% germination) and beans and maize are intolerant (< 30 % germination). The paraffin had a negative influence on the rate of germination but there were no statistically significant differences between the 25% to 100% paraffin concentrations. Measurements of the quantity of water and of paraffin absorbed were done after seeds of the seven crop species were immersed in 0, 25, 50, 75 and 100% paraffin concentrations for 30 minutes. Beans absorbed more water at 100% water and more paraffin at 25% paraffin than the other crop species. The paraffin uptake decreased with the increase of paraffin concentration while water uptake increased with the increase in water percentage. In both cases canola had the lowest uptake. Differential uptake of water and paraffin did not explain the results of the germination test. Seeds of the seven crop species immersed in different paraffin concentrations (0, 25, 50, 75 and 100%) for thirty minutes were dried and then soaked in distilled water for 20 hours. The electrical conductivity (EC) of the liquid was determined by means of an EC meter after 20 hours of soaking. This was done to investigate whether paraffin treatment influenced leaking of electrolytes, which would indicate damage to the cell membranes in the seed. Results showed that sunflower leaked more electrolytes than any other seed, while wheat and maize had lower electrolyte leakage than the other species. This showed that the negative effect of paraffin on the germination of some crop species was unlikely to be due to membrane damage because sunflower seeds that leaked most electrolytes had a high germination percentage while the maize and wheat seeds that leaked little electrolytes, had poor germination after paraffin treatments. The second experiment was conducted in a glasshouse. Seeds of the seven crop species were subjected to the same PC and TOI treatments as described in the germination experiment above but instead of being placed in an incubator to germinate, they were planted in 8cm x 8 cm plastic pots (10 seeds in each) in coarse sand in a glasshouse that was running at approximately 20ºC. The establishment of the seedlings was monitored daily in the glasshouse. The final percentage of establishment was calculated. Three weeks after planting, the seedlings were thinned to one plant per pot. The mean root and stem lengths as well as dry mass of the seedlings was recorded when the seedlings were thinned. The one plant per pot that was retained was harvested six weeks after establishment. Root and stem length and dry mass were determined. Establishment percentage and tolerance indices were calculated. Maize and beans showed the lowest establishment percentages and sunflower scored the highest establishment percentage after treatment with paraffin. The root and stem lengths of the crops were generally unaffected by paraffin treatments. In terms of dry mass paraffin had a significant negative effect on groundnut at three weeks but at six weeks no effect of paraffin on any of the vegetative growth parameters could be observed. The third experiment was run in the microscope laboratory. A test using a confocal and fluorescence microscope was carried out to determine if residues of paraffin could be found in germinating soya bean seeds and seedlings. Specimens collected from the germinating soya bean seed and seedlings were mounted on the fluorescent microscope and stained with a solution of 100 μg.ml-1 Nile Red and observed with LD Plan-Neofluar 60X/0.6. Results showed that paraffin did penetrate the soya bean seed and was translocated within the plant system (endodermis) as the plant grows. The concentrations of paraffin in the tissue were however quite low. The fourth experiment was run on the Langgewens Experimental Farm near Moorreesburg in the Western Cape Province. Forty blocks were spatially grouped into two separate groups. Twenty blocks received the five paraffin treatments replicated four times and the other twenty blocks received the five water treatments also replicated four times. Within each group the treatments were allocated randomly to the plots. The experimental design was a 2X5 Factorial experiment with factors Treatment liquid (distilled water and paraffin) and Time of immersion (0, 1, 5, 10 and 30 minutes) replicated four times. No pesticides were applied to the canola crop. Stand density, leaf area and dry mass were recorded at the first harvest at 12 weeks, and then dry mass was determined at 21weeks. Final yield was determined after 27 weeks when the plots were harvested by means of a combine plot harvester. The stand density, leaf area and dry mass were significantly increased by paraffin treatments at the time of the first harvest. After 21 weeks paraffin treatment had no significant effect on the dry mass production of the canola and the same was true of the final seed yield. . Even though there was no serious attack by pests, the little feeding damage that occurred in the water treated plots and not in the paraffin treated plots, indicate that paraffin may have a repellent effect. Paraffin had no negative effects whatsoever on the growth and yield of canola in this experiment. This study indicates that different crops react differently to seed treatment with paraffin. The results of the fourth experiment indicate that paraffin might be used as pest repellent on certain selected crops but more research is needed on the subject. / AFRIKAANSE OPSOMMING: Paraffien, ook genoem keroseen, word deur kleinskaalse boere in sekere dele van Afrika gebruik as ‘n pesafweermiddel. Dit word beweer dat die afweeraksie suksesvol is teen parasiete tydens saadontkieming en vroeë saailinggroei. Saad word in kommersiële paraffien gedoop vir ‘n paar sekondes en dan onmiddelik daarna geplant. Die metode skep vrae oor die moontlike negatiewe gevolge op die saad na die imbiberingsproses maar ook op mense en diere wat die plante en sade benut. Eksperimente is beplan om vas te stel of die praktyk negatiewe gevolge op die saadontkieming en groeikragtigheid van die daaropvolgende saailinge van sewe geselekteerde gewasspesies sal hê. ‘n Eksperiment is ook uitgevoer om die effektiwiteit van paraffien as pesafweermiddel op kanola in ‘n veldsituasie te toets. Die data wat ingesamel is is ontleed deur gebruik te maak van STATISTICA, sagteware, uitgawe 11. Waar betekenisvolle interaksies of verskille binne hooffaktore voorgekom het, is die gemiddeldes geskei deur middel van Fischer se LSD post-hoc ontleding by p = 0.05. Die eerste reeks eksperimente is uitgevoer in ‘n laboratorium. Dit is uitgevoer op sade van sewe gewasspesies naamlik . kanola (Brassica napus L.), gewone bone (Phaseolus vulgaris L.), grondbone (Arachis hypogea L.), mielies (Zea mays L.), sojabone (Glycine max L.), sonneblom (Helianthus annuus L.) en koring (Triticum aestivum L.). In die ontkiemingsproef is die sade onderwerp aan ‘n 7X5X4 ewekansige blokontwerp wat faktoriaal gerangskik is met faktore Gewasspesies (CS) (sien hierbo), Paraffien konsentrasie (PC) (0, 25, 50, 75 en 100% van kommersiële paraffien verdun met gedistilleerde water) en Tyd van indompeling (TOI) (1, 5, 10, en 30 minute). Behandelings is vier keer herhaal. Na indompeling is die sade met waterabsorberende papier gedroog en onmiddelik daarna in 90 mm deursneë petribakkies wat twee filtreerpapiere en 5 ml gedistilleerde water bevat het, ontkiem. Tien sade per petribakkie is gebruik en die petribakkies is geïnkubeer by ‘n konstante temperatuur van 20ºC in die donker in ‘n inkubasiekas. Resultate het getoon dat kanola, sonneblom en sojaboon bestand is teen paraffienbehandelings (>70% ontkieming), koring en grondboon is minder bestand (30-70% ontkieming) en mielies en gewone bone is sensitief vir paraffienbehandeling (<30% ontkieming). Die paraffien het oor die algemeen ‘n negatiewe effek op ontkiemingstempo gehad maar daar was geen statisties betekenisvolle verskille tussen die 25% en 100% paraffienbehandelings nie. Die hoeveelheid water en paraffien wat opgeneem is deur sade van die sewe gewasspesies nadat dit in paraffienkonsentrasies van 0, 25, 50, 75 en 100% ingedompel is vir 30 minute, is bepaal. Gewone bone het meer water by die 100% water behandeling en meer paraffien by die 25% paraffien behandeling opgeneem as die ander spesies. Die paraffienopname het afgeneem met toename in paraffienkonsentrasie terwyl wateropname toegeneem het met toenemende waterkonsentrasies. Beide in geval van wateropname en paraffienopname het kanola die minste water opgeneem. Differensiële opname van water en paraffien het nie die resultate van die ontkiemingstoets verklaar nie. Sade van die sewe gewasspesies is in verskillende paraffienkonsentrasies (0, 25, 50, 75 en 100%) gedompel vir 30 minute, gedroog en daarna in gedistilleerde water geweek vir 20 uur. Aan die einde van die 20 uur wekingsperiode is die elektriese konduktiwiteit (EC) van die wekingsvloeistof bepaal deur middel van ‘n EC meter. Dit is gedoen om vas te stel of paraffienbehandeling die uitlek van elektroliete vanuit die saad, wat ‘n aanduiding van beskadigde selmembrane van die saad kan wees, beïnvloed. Resultate het aangedui dat sonneblom die meeste elektroliete vrygestel het en koring en mielies die minste. Dit dui aan dat die negatiewe invloed van paraffien op sommige gewasspesies waarskynlik nie deur membraanbeskadiging veroorsaak is nie omdat sonneblom, wat die meeste elektroliete vrygestel het, die hoogste ontkiemingspersentasie na behandeling met praffien gehad het terwyl mielies en koring, wat die minste elektroliete vrygestel het, baie swak ontkieming gehad het na paraffienbehandeling. Die tweede eksperiment is in ‘n glashuis uitgevoer. Sade van die sewe gewasspesies is onderwerp aan dieselfde paraffienkonsentrasies en tye van indompeling as in die ontkiemingseksperiment hierbo maar in plaas van om die sade in ‘n inkubasiekas te ontkiem, is dit in 8 cm x 8 cm plastiekpotte wat gevul is met growwe sand geplant (10 sade per pot) in ‘n glashuis wat by ‘n konstante temperatuur van ongeveer 20ºC geloop het. Die vestiging van die saailinge in die glashuis is daagliks gemonitor en die finale persentasie van vestiging is bereken. Drie weke na plant is die saailinge uitgedun sodat een per pot oorgebly het. Die uitgedunde saailinge se gemiddelde wortel- en stamlengtes is bepaal asook die gemiddelde droëmassas. Die een plant wat per pot oorgebly het is na ses weke ge-oes en weer is wortel- en stamlengtes bepaal asook die droëmassas. Vestigingspersentasies en toleransie indekse is bereken. Mielies en gewone bone het die laagste vestigingspersentasies getoon en sonneblom die hoogste nadat die gewasse met paraffien behandel is. Die wortel- en stamlengtes van die gewasse was oor die algemeen nie deur paraffienbehandelings beïnvloed nie. In terme van droëmassa het paraffien ‘n negatiewe effek op grondbone gehad drie weke na plant maar na ses weke kon geen invloed van paraffienbehandelings op enige van die vegetatiewe groeiparameters waargeneem word nie. Die derde eksperiment is in ‘n mikroskooplaboratorium uitgevoer. ‘n Konfokale en fluoreserende mikroskoop is gebruik om te bepaal of oorblyfsels van paraffien gevind kan word in ontkiemende sojaboonsade en saailinge. Monsters wat geneem is van die ontkiemende sojaboonsade saailinge is gemonteer op die fluoreserende mikroskoop en gekleur met ‘n oplossing van 100 μg.ml-1 Nile Red oplossing en ge-evalueer met LD Plan-Neofluar 60X/0.6. Resultate het getoon dat paraffien wel die sojaboonsaad kon infiltreer en dat dit ook in die saailinge se endodermis vervoer kon word en opspoorbaar was. Die konsentrasies van paraffien in die weefsel was egter laag. Die vierde eksperiment is uitgevoer op die Langgewens Proefplaas naby Moorreesburg in die Wes-Kaap Provinsie. Veertig blokke is ruimtelik in twee groepe van twintig elk grangskik. Twintig blokke het die vyf paraffienbehandelings ontvang en twintig die vyf gedistilleerde waterbehandelings. Die behandelings is vier keer herhaal. Binne elke blok is die behandelings ewekansig toegeken aan persele. Die proefontwerp was ‘n 2X5 ewekansige geneste blokontwerp (split plot) wat faktoriaal gerangskik is met faktore Behandelingsvloeistof (gedistilleerde water en paraffien) en indompelingstyd (0, 1, 5, 10 and 30 minute). Geen insekdoders is op die kanola toegedien nie. Plantdigtheid, blaaroppervlakte en droëmassa is bepaal tydens die eerste monsterneming 12 weke na plant en daarna is slegs droëmassa bepaal na 21 weke. Na 27 weke is finale oesopbrengs bepaal deur die persele met ‘n perseelstroper te stroop. Plantdigtheid, blaaroppervlakte en droëmassa is betekenisvol verhoog deur paraffienbehandelings na 12 weke. Na 21 weke het die paraffienbehandelings egter geen betekenisvolle invloed op die droëmassa van die plante gehad nie en daar was ook nie verskille ten opsigte van finale oesopbrengs nie. Alhoewel daar nie ernstige insekskade waargeneem is nie, was dit tog duidelik dat die bietjie vreetskade wat in die waterbehandelings voorgekom het, nie in die paraffienbehandelings voorgekom het nie. Dit dui aan dat die paraffien moontlik ‘n afwerende invloed gehad het. Paraffien het geen negatiewe invloed enigsins gehad op die groei en produksie van kanola in hierdie eksperiment nie. Hierdie studie dui aan dat verskillende gewasse verskillend reageer op saadbehandeling met paraffien. Die resultate van die vierde eksperiment dui aan dat paraffien moontlik as ‘n pesafweermiddel op sekere geselekteerde gewasse gebruik kan word maar meer navorsing word benodig op die onderwerp.

Thesis (MScAgric)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: A new orange oil based soil ameliorant is available on the market. Apart from the orange oil, the other main constituents of the product are a nonionic surfactant and an anionic surfactant. Surfactants are used in the agricultural sector, amongst others, as a countermeasure for soil with poor infiltrability or with hydrophobic characteristics. Farmers who applied the orange oil based soil ameliorant to the soil observed a positive growth response by the crop. However, the main concern about surfactants is that it can cause the soil to disperse and thereby decrease the infiltration and saturated hydraulic conductivity thereof. The aim of this study was therefore to determine the effect which this product might have on the following selected soil physical properties: bulk density, aggregate stability, soil strength and unsaturated hydraulic conductivity. The product was applied on four farms on soils with different textures: Dublin Farm (22% clay), Wansbek (20% clay), Toitskraal (7% clay) and Two Rivers (3% clay). Field studies were repeated at Dublin Farm and Toitskraal to study the longevity effect of the product. Differences in bulk density were not attributed to the effect of the product, but to spatial variation. The aggregate stability at the 50 mm depth tended to decrease after application of the product at Dublin Farm trial 1, Toitskraal trial 1 and at Wansbek. At Dublin Farm trial 2 and Toitskraal trial 2 the application of the product tended to increase the aggregate stability. For Dublin Farm trial 2 and Wansbek the shear strength at the 50 mm depth tended to increase with increased application rates. The opposite was observed at Toitskraal and Two Rivers. The unsaturated hydraulic conductivity tended to be higher at the 0 mm depth for the treated soils at all of the trials except Toitskraal trial 2. From the aggregate stability results it is clear that the initial effect of the product was detrimental which can be attributed to the anionic surfactant. The long term effect can be attributed to the effect of the nonionic surfactant. The differences in shear strength can be attributed to aggregate stability (for Dublin Farm trial 2) and bulk density (for Two Rivers). There is however no explanation for the results found at Toitskraal and Wansbek. From the linear regression of bulk density against unsaturated hydraulic conductivity for Wansbek and Two Rivers it is clear that the application of the product definitely had an influence on the unsaturated hydraulic conductivity. For both farms, the correlation between bulk density and unsaturated hydraulic conductivity was better for the control than for the treated soils. To conclude with, the application of the product according to the recommended application rate, resulted in a slightly detrimental effect to the soil on the short term, but on the long term it tended to have a slightly positive effect on the soils. / AFRIKAANSE OPSOMMING: ‘n Nuwe grondverbeteringsproduk met lemoenolie as ‘n basis en ‘n nie-ioniese en ‘n anioniese benattingsmiddel as hoof bestandele, is op die mark. In die landbou sektor word benattingsmiddels onder andere gebruik as ‘n teenvoeter vir gronde met swak infiltrasie of hidrofobiese eienskappe. Die grootste voorbehoud omtrent die gebruik van benattingsmiddels is die moontlike afname in infiltrasie en versadigde hidroulieses geleivermoë as gevolg van klei dispergering. Positiewe reaksies van die gewasse is waargeneem deur boere wat van die produk gebruik maak. Die doel van die studie was dus om die moontlike effek van die bogenoemde grondverbeterings produk op die volgende geselekteerde grondfisiese eienskappe te bepaal: bulkdigtheid, aggregaatstabiliteit, grondsterkte en onversadigde hidrouliese geleivermoë. Die produk is toegedien op vier plase met verskillende grondteksture: Dublin Farm (22% klei), Toitskraal (7% klei), Wansbek (20% klei) and Two Rivers (3% klei). ‘n Ondersoek na die lewensduur van die produk is gedoen deur ‘n opvolg studie te doen by Dublin Farm en Toitskraal. Vir die bulkdigtheid resultate kon geen van die verskille toegeskryf word aan die effek van die produk nie. Die aggregaate stabiliteit by die 50 mm diepte van Dublin Farm proef 1, Toitskraal proef 1 en Wansbek, het geneig om laer te wees vir die behandelde gronde. Die aggregaatstabiliteit by die 50 mm diepte van Dublin Farm proef 2 en Toitskraal proef 2 het geneig om hoër te wees vir die behandelde gronde. Die skuifsterkte by die 50 mm diepte by Dublin Farm proef 2 en Wansbek, het geneig om toe te neem met ‘n toename in toedienings hoeveelheid, terwyl die teenoorgestelde tendens by Toitskraal en Two Rivers waargeneem is waar minder klei teenwoordig is in die grond. Die onversadigde hidroliese geleivermoë het geneig om hoër te wees by die 0 mm diepte van al die plase met die uitsondering van Toitskraal proef 2. Dit is duidelik vanaf die aggregaatstabiliteit resultate dat die aanvanklike effek van die produk nadelig is en dit kan toegeskryf word aan die effek van die anioniese benattingsmiddel. Die langtermyn effek kan toegeskryf word aan die nie-ioniese benatingsmiddel wat aggregaatstabiliteit kan verbeter. Die verskille in skuifsterkte kan toegeskryf word aan die verskille in aggregaatstabiliteit (vir Dublin Farm proef 2) en bulkdigtheid (vir Two Rivers). Daar is egter geen verklaring vir die verskille in skuifsterkte by Toitskraal en Wansbek nie. Die liniêre regressie van bulkdigtheid teenoor onversadigde hidroliese geleivermoë van Wansbek en Two Rivers dui aan dat die produk ‘n invloed het op die onversadigde hidroliese geleivermoë. Vir albei plase het die kontrole die beste liniêre verband tussen die twee grondeienskappe gehad, met ‘n swakker korrelasie vir gronde waar die lemoenolieproduk toegedien is. Dus kan die afleiding gemaak word dat op die korttermyn het die produk ‘n geringe negatiewe effek op die grond, maar op die langtermyn neig dit om ‘n positiewe effek te hê.

Thesis (MScAgric)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Soil amelioration and conditioning is desirable and in many cases essential, due to increasing food demand and the deterioration and exhaustion of soils. A new soil ameliorant, consisting of orange oil as a base and a mixture of surfactants, is on the global agricultural market. Use of this soil ameliorant by farmers has made an impact on crop production and plant growth on many farms. The effects of this soil ameliorant on selected soil properties as well as plant traits were evaluated by a field trial, a pot trial and a Water Characteristic Curve experiment. A field trial was performed in the Firgrove area near Somerset West, Western Cape (South Africa). It entailed the evaluation of the water content and lateral movement of water in a sandy soil after the application of the soil ameliorant. The field was already planted with Capsicum annuum crop at the initiation of the trial. The trial was performed in a drip irrigated field by taking soil water measurements using a Diviner 2000 probe over a nine week period. The trial showed significant increases in water content on the plots treated with the soil ameliorant. These increases are indicative of an increase in the lateral movement of the soil water, as the measurements were taken between two drippers. On average, the ameliorant treated soil had 17% higher water content than that of the control. A Water Characteristic Curve (WCC) experiment was conducted, which entailed establishing the WCC for a sandy soil treated with the soil ameliorant. The Sandbox apparatus, from Eijkelkamp Agrisearch Equipment, was used to perform the experiment and provides suction values of 0.1 to 10.1 KPa. The WCC showed that the ameliorant application increased water retention over all suctions, especially for the 10 l/ha ameliorant application. This substantiated the Field trial where water retention was increase in a sandy soil. A pot trial was performed in a greenhouse to evaluate the effect of the soil ameliorant on selected soil properties and certain plant traits. This experiment consisted of an ameliorant treatment and a control with a combination of four different Plant Available Water Depletion (PAWD) regimes namely, 10% depletion, 50% depletion, 80% depletion and 50%C depletion, where “C” refers to covered. The trial layout, with five single pot replicates per treatment combination, was according to a randomized block design. The surface covering of one of the 50% PAWDs was a plastic sheet which to prevent evaporation from the soil surface. The ameliorant treatment resulted in significant improvements in overall plant growth, total biomass production, especially dry root biomass. Leaf Area Index and plant height were also improved. The Biomass Water Use Efficiency was improved with the ameliorant application, especially for the 50%C PAWD illustrating the beneficial use of a mulch. Bulk density was decreased with application of the ameliorant but this difference was not statistically significant. Aggregate stability for the moist soils (10% and 50%C PAWD) was significantly improved with the ameliorant application. The application of this soil ameliorant made significant improvements in various facets of plant growth and certain soil physical properties. Especially water holding capacity in sandy soils and the overall improvement in plant growth. There is still much opportunity for research in this field and many questions remain, especially those pertaining to the mechanisms involved in the workings of a soil ameliorant containing a mixture of ingredients. / AFRIKAANSE OPSOMMING: Die bestuur van besproeingswater en die optimisasie van gewasproduksie is `n studieveld wat baie aandag verg, aangesien varswater bronne bedreig word. As gevolg van die stygende vraag na voedsel en die agteruitgang en uitputting van die grond, is grondverbetering en-kondisionering aanbeveelbaar en in sommige gevalle noodsaaklik. `n Nuwe grond verbeteraar, bestaande uit lemoen olie as `n basis en ‘n mengsel van benattingsmiddels, is beskikbaar op die wêreld landbou mark. Die gebruik van die grondverbeteraar deur boere het ‘n impak gemaak op gewasproduksie en plantegroei op baie plase. Die effek van die grondverbeteraar op geselekteerde grond-eienskappe sowel as plantkenmerke is geevalueer deur ‘n veld proef, ‘n pot proef en ‘n Water Karakeristieke Kurwe eksperiment. `n Veldproef is uitgevoer in die Firgrove omgewing naby Somerset Wes in die Wes-Kaap Provinsie, Suid Afrika. Die veldproef het die evaluasie van die grondwater inhoud en die laterale beweging van water in `n sanderige grond behels. Die gewas Capsicum annuum was alreeds in die veld aangeplant voor die begin van die proef. Die proef was uitgevoer in `n drup besproeide veld deur grondwater metings wat geneem is met `n Diviner 2000 peilstif oor `n periode van nege weke. Die proewe het `n beduidende verhoging in die groundwater-inhoud getoon waar die grond met die grondverbeteraar behandel is. Die verhogings was `n aanduiding van `n toename in die laterale vloei van grond water, aangesien die lesings tussen twee druppers geneem is. Die grond, wat met die grondverbeteraar behandel is, het gemiddeld 17% hoёr groundwater-inhoud gehad as die kontrole. `n Water Karakteristieke Kurwe (WKK) eksperiment is uitgevoer, wat bestaan het uit die opstel van die WKK vir `n sanderige grond behandel met die grondverbeteraar. Die “Sandbox” apparaat van Eijkelkamp, Agrisearch Equipment is gebruik wat negatiewe druk waardes van 0.1 tot 10.1 KPa toon. Die WKK het getoon dat die toediening van die grondverbeteraar die water retensie verhoog het oor al die drukke, veral in die 10 l/ha toediening. Dit staaf die resultate van die Veld eksperiment waar water retensie verhoog is in die sanderige grond. Die pot-eksperiment is uitgevoer in `n tonnel om die effek van die grondverbeteraar op geselekteerde grond eienskappe en verskeie plant eienskappe te evalueer. Die eksperiment het bestaan uit ‘n grondverbeteraar behandeling en ‘n kontrole met ‘n kombinasie van vier verskillende plantbeskikbare wateronttrekkings naamlik, 10%, 50%, 80% onttrekking, en ‘n 50%C onttrekking, waar “C” verwys na “covered”. Die proef uiteensetting, met vyf enkel pot herhalings per behandeling kombinasie was volgens ‘n ewekansig blok uitleg. Die oppervlakte dekking van 50%C plantbeskikbare waterottrekking was `n 60 μm plastiek-vel wat verdamping vanaf die grondoppervlak verhoed het. Die grondverbeteraar behandeling het `n beduidende verbetering in algehele plantgroei, totale biomassa produksie en spesifiek droё wortel biomassa getoon. Die blaararea indeks en planthoogte het ook `n verbetering getoon. Die biomassa-watergebruiksdoeltreffendheid het verbeter met die toediening van die grondverbeteraar, spesifiek vir die 50%C plantbeskikbarewaterottrekking wat die voordele van die gebruik van oppervlakdekking illustreer. Die brutodigtheid is verminder deur die toediening van die grondverbeteraar, maar die verskil was statisties nie wesenlik nie. Agregaat-stabiliteit vir die grond met `n hoёr vogregime (10% en 50%C plantbeskikbare waterottrekking) is wesenlik verbeter met die toediening van die grondverbeteraar. Die toediening van die grondverbeteraar het wesenlike verbeteringe in verskeie plantegroei- en grondfisiese-eienskappe getoon. Spesifiek laterale beweging in sanderige grond en die verbettering van algehele plantegroei. Daar is nog baie geleenthede vir navorsing in die veld en baie vrae bly onbeantwoord, veral in verband met die meganismes met bretrekking tot die werking van die grondverbeteraar wat uit `n mengsel van bestandele bestaan.

Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The availability of water for irrigation purposes is becoming a serious concern for smallholder famers in the former homeland areas of South Africa. Not only because of global weather change and the occurrence of more erratic weather events, but also due to competition for fresh water between the agricultural, industrial and domestic sectors (Hamdy et al., 2003). Food production increases in smallholder agriculture is seen as a possible solution to the food security challenges in the rural areas of the Limpopo Province (Altman et al., 2009). Smallholder farmers in Giyani mostly use traditional furrow irrigation systems and their farm crop productivity remains very low, compared to commercial farms in the same area. The objective of this study is to utilize and test various innovation technologies aimed at increasing Water Productivity (WP) in order to facilitate better irrigation management of the available water resources. The study was conducted on two farms, Zava Cooperative Garden and Mzilela Cooperative Garden, in the rural areas of Giyani over a two year period from 2012-2013. This study seeks to achieve the objective in three distinct ways. Firstly, the use of NIR technology is used to evaluate the prediction ability of soil chemical parameters for fertilizer requirement calculations. Secondly, WP trials were conducted on smallholder tomato (Solanum lycopersicum) production for three consecutive seasons, evaluating their current tomato crop production systems and also testing new innovations for WP increases. Thirdly, applying the MonQI methodology, inputs and outputs of all crop production sites were done to monitor the cropping systems throughout the period of the research. The results from this study indicate the importance of applying new innovations amongst smallholder production systems. Important findings from the NIR technologies indicated that this innovation can improve soil nutrient management in a more affordable, user friendly manner. The results showed that good prediction models were obtained for pH (KCl), electrical conductivity (EC), P, K, Mg, Na and CEC, with R2 and RPD values larger than 0.60 and 1.4 respectively. The prediction of exchangeable Ca was less successful with a R2 value of 0.43. Results from the WP trials suggest that drip irrigation performed better than furrow irrigation in terms of yield and WP. Yield and WP were very low for all treatments, being below 32 t/ha and 5.2 kg/m-3 respectively. Improved management practices, such as soil nutrient management and mulching were introduced in the 2nd and 3rd seasons of tomato trials in order to increase WP at field level at Mzilela farm. Results showed tomato yield increased from an average of 26.5 t/ha to 120.9 t/ha and WP increases from 4.61kg/m-3 to 17.69 kg/m-3. Deep drainage of water out of the rootzone decreased with better irrigation management. The results from the monitoring of inputs and output of their cropping systems revealed that smallholder farmers, using traditional farming practices, yielded very low and mostly below 5 t/ha for all crops. Some crops were totally lost due to hail and heat-waves. NPK balances for conventional cropping by the smallholder farmers at Mzilela was in the range of 0 to -70 kg/ha. The tomato production fertilized treatment of the 1st, 2nd and 3rd WP trials, showed positive nutrient balance results for P and K in the range of 80 to 140 kg/ha. N balances were mostly negative for all plots. NFI was R2768 and R4740 for season 1 and 3 respectively, while the 2nd season results showed a loss of - R5176. With the improved yield from the WP trial sites, and the fruits being sold to the Spar, the NFI increased to R42486 in the final season. The study concludes that great improvements in yield, WP and NFI are attainable and sustainable amongst smallholder farmers in the Giyani area. / AFRIKAANSE OPSOMMING: Die beskikbaarheid van water hulpbronne vir besproeiings doeleindes onder kleinskaalse boere in die voormalige tuislande is besig om ernstige bekommernisse te wek. Nie net as gevolg van globale weer veranderinge en meer gereelde ekstreme weer toestande nie, maar ook as gevolg van die kompetisie tussen die landbou, industriële en huishoudelike sektore vir water gebruike (Hamdy et al., 2003). Verhoogde voedsel produksie onder die kleinskaalse landbou sektor word gesien as moontlike oplossing vir die voedsel sekuriteit uitdagings in die platteland areas van die Limpopo Provinsie in Suid-Afrika (Altman et al., 2009). Kleinskaalse boere in Giyani gebruik meestal tradisionele voor-besproeiings stelsels en hul produktiwiteit bly steeds baie laag wanneer dit met kommersiële boerderye vergelyk word. Die hoofdoel van hierdie studie is om Water Produktiwiteit (WP) te bestudeer en verskeie innovasie tegnologieë te toets om beter besproeiing bestuur van kosbare water bronne te fasiliteer. Die studie was uitgevoer op twee plase, naamlik Zava Koöperatiewe Tuin en Mzilela Koöperatiewe Tuin, wat in die plattelandse areas van Giyani geleë is en die studie is gedoen oor ‘n periode van twee jaar vanaf 2012 tot 2013. Om hierdie doelwit te bereik was die navorsing in drie eenhede uitgevoer. Eerstens sal Naby-Infra Rooi (NIR) tegnologie gebruik word om die voorspelling vermoë van grond chemiese eienskappe te toets vir meer effektiewe grond voedingstof bestuur deur kleinboere. Tweedens sal WP proewe uitgevoer word op kleinskaalse tamatie (Solanum lycopersicum) produksie. Die huidige tamatie gewasproduksie stelsels was getoets om die WP statusse te evalueer van hul tradisionele bestuurs praktyke van beide drip- en voorbesproeiings stelsels. Laastens, is insette en uitsette van die kleinboere se produksie stelsels met die MonQI metodologie bestudeer om die huidige produksie sisteme te evalueer, sowel as die WP proef persele, deur opbrengs, grond voedingstof balanse en netto plaas inkomste (NPI) te moniteer en te bereken vir 4 half jaar seisoene gedurende die navorsings periode. Die resultate van die navorsing voer aan dat die gebruik van innovasie tegnologieë onder kleinskaalse boerderystelsels ontsettend belangrik is vir verbeterde produksie. Hoofbevindings van die NIR tegnologie dui dat meer doeltreffende grond voedingstof bestuur moontlik is en wat goedkoper en meer gebruikersvriendelik is vir kleinboere. Hierdie tegniek het goeie voorspelbaarheid-modelle getoon vir pH (KCl), Elektriese Geleiding (EG), P, K, Mg, Na en katioon uitruilings kapasiteit (KUK) met R2 en RPD waardes hoër as 0.60 en 1.4 onderskeidelik. Die voorspelbaarheid van Ca was minder suksesvol met ‘n R2 waarde van 0.43. Die resultate van die WP toetse wys dat drip besproeiing beter as voorbesproeiing presteer het in terme van opbrengs en WP. Opbrengs en WP was baie laag vir alle behandelings van seisoen 1, met waardes laer as 32 t/ha en 5.2 kg/m-3 onderskeidelik. Verbeterde bestuurspraktyke, soos grond voedingstof bestuur asook die gebruik van ‘n deklaag, was in die 2de en 3rde seisoen toegepas om opbrengs en WP te verhoog op plaasskaal op Mziela plaas. Resultate het gewys dat opbrengs verhoog het van ‘n gemiddelde van 26.5 t/ha tot 120.9 t/ha en WP verhoging van 4.61 kg/m-3 tot 17.69 kg/m-3. In terme van die insette en uitsette van die produksie sisteme het opbrengste van alle gewasse, wat nog van tradisionele metodes gebruik, laer as 5 t/ha getoon. Soms van die totale oeste verloor deur hael of hittegolwe. Die NPK balanse vir die gewasverbouing met konvensionele kleinboer metodes was in die orde van 0 tot -70 kg/ha. Die kunsmis behandelings van die tamatie proewe van die 1ste, 2de en 3rde WP seisoene het positiewe balanse getoon vir P en K in die orde van 80 tot 140 kg/ha. Die N balanse was meestal negatief vir alle verbouings persele. Die NPI was R2768 en R4740 vir seisoen 1 en 3 onderskeidelik, terwyl die 2de seisoen verlies van -R5176 getoon het. Die verbeteringe in opbrengs met die WP proewe en met die verkoop van die tamaties aan die Spar was die NPI vir die 4de seisoen R42486. Die studie sluit dat daar groot moontlikehede is vir verhoging in opbrengs, WP en NPI onder kleinboere in die Giyani area.

Thesis (MScAgric (Viticulture and Oenology))--University of Stellenbosch, 2006. / The quality of wine is influenced by numerous factors of which the grapes, winemaking techniques and effective quality control are to name a few. The use of new techniques should be cost effective and always have a positive influence on the wine quality. The addition of commercial tannins to wine is a fairly new technique and the effects of these additions at the concentrations prescribed have not been investigated in detail. The commercial tannins can be added to wine for different reasons, which may include: stabilisation of colour, increasing the aging potential, to modify aromas, promote precipitation of proteins, limit the effect of laccase activity, substrate for micro-oxygenation, to act as a redox buffer and structural and mouth feel modification. The reason for the addition determines the type of commercial tannin that is used, the timing of the addition and the dosage used.

Thesis (MscAgric (Viticulture and Oenology))--University of Stellenbosch, 2007. / Regal Seedless is a white, seedless grape which has the potential to become a profitable cultivar for the table grape producer since it has the advantages of early season harvesting and inherently large berries. There is, however, a downside to this cultivar, namely the seasonal occurrence of an unacceptable, astringent taste. This negative taste affects the demand by local and international markets. The astringency perception is due to the presence of phenolic compounds. It is well known that the phenolic composition and concentration change during the ripening of the grape. Different postharvest treatments are applied to fresh fruit like persimmons to remove astringency. These treatments include the use of carbon dioxide, nitrogen and ethanol. The aim of this study was to determine the optimum maturity level for Regal Seedless where the phenolic concentration is the lowest and the astringent taste acceptable. The use of postharvest treatments to manipulate the taste and the phenolic content, were also investigated. The effect on other quality parameters like total soluble solids (TSS), pH and total titratable acidity (TTA) were also evaluated.

Thesis (MScAgric (Viticulture and Oenology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Previous research has shown that carotenoids are precursors of C13-norisoprenoid aroma compounds in wine. C13-norisoprenoids have low threshold values in wine with the most prominent C13-norisoprenoids being β-damascanone and β-ionone which contribute honey and floral like aroma to wine. Chlorophyll and its derivates have also been detected in wine with potential to be precursors to aroma compounds. Apart from the contribution of these pigments to wine aroma and quality they are vital role players in photosynthesis and are widely found in plants and plant products. The main functions of these pigments in plants are light collection and light-protection. Research has shown that environmental conditions, climate, light exposure of bunches and soil water deficit influence the carotenoid content of grape berries. Furthermore the concentration of carotenoids and chlorophylls has also been shown to differ between cultivars. No research in this regard has been done on Merlot grape berries. With this in mind, the aim of this study was to evaluate the effect of vigour and soil water content on the evolution of carotenoids and chlorophylls through ripening of grape berries from the cv. Merlot. However, when looking at methods to analyse carotenoids and chlorophylls in berry tissue, especially lyophilised tissue, there were no readily available methods. Thus, an extraction method to identify and quantify the carotenoid and chlorophyll profile of lyophilised tissue from unripe (green) to ripe (red) Merlot grape berries was needed. In this study the RPHPLC method of Taylor et al. (2006) for carotenoids and the extraction method of Mendes-Pinto et al. (2004) were adapted to analyse both carotenoids and chlorophylls in lyophilised grape tissue. The RP-HPLC method baseline separated all the carotenoids and chlorophylls and their derivatives. Recovery of standards from mock extractions was high, indicating that the extraction procedure was acceptable. However, extraction recovery tested in the matrix of the grape tissue showed less promising results due to the high acid content of grape tissue. Violaxanthin, neoxanthin and the chlorophylls were especially sensitive to low pH conditions which facilitated their degradation. The degradation products of these compounds under acidic conditions were identified as pheophytin a, b, chlorophillide a, pyropheophytin b, cisviolaxanthin, cis-neoxanthin, neochrome, mutatoxanthin and luteoxanthin. There is a possibility that some degradation products were already present in the tissue due to lyophilisation (since the water in the berry was then removed and the acid concentrated). More work is needed to investigate the effect of lyophilisation and storage on the composition of grape tissue of different maturity. The extraction method for grape berry tissue at different ripening stages should also be optimised further to effectively neutralise tissue acidity, without compromising the extraction of carotenoids significantly, in especially green berry tissue. The question as to whether cisisomers and chlorophyll degradation products are naturally present in grape berries or are formed during sampling and processing remains unanswered in the current study. This study confirmed that in general carotenoids and chlorophylls decrease on a per berry (μg/berry) and concentration (μg/g) basis from veraison to harvest. Furthermore, this study was inconclusive in showing that vigour differences have an effect on the rate of synthesis/degradation of carotenoids, chlorophyll and some other ripening parameters, namely malic acid, total glucose and fructose, total tannin and total anthocyanin, from pre-veraison (pea size) to harvest. Additionally, no significant effect of soil water content on carotenoids, chlorophylls and ripeness parameters was found in this study, most likely due the fact that high soil water capacity was found in lower soil layers which may have prevented significant differences in grapevine water status. Experimental plots selected for vigour differences based on normalised difference vegetation index (NDVI) images, pruning mass and soil water measurements by means of a neutron probe, showed significant differences in soil water content in only the first 30 cm of the soil for the ripening seasons studied. Predawn plant water potential measurements, however, indicated that none of the experimental vines experienced severe water stress which was previously shown to effect carotenoid content of grapes. The carotenoid 5,8-epoxy--carotene was quantified for the first time in grapes and represents a significant amount of the total carotenoids present at harvest. All the carotenoids and chlorophylls except -carotene appeared to be sensitive to seasonal variation in climatic conditions. Lutein and β-carotene were found to be the most abundant carotenoids present in Merlot grape berries together with chlorophyll a for both seasons studied. The values of these carotenoids also correlated well with previous research. However, chlorophyll a was found in much larger quantities in Merlot berries compared to reported data. This is possibly because in this study the chlorophyll degradation products were included in the calculation of chlorophyll a. Multivariate analysis showed promising preliminary prediction models (with correlation values of above 0.8 for both seasons analysed) for the prediction of the concentration of ripeness parameters (glucose, fructose, malic acid, total tannins and anthocyanins) with carotenoid and chlorophyll content. This result highlights the opportunity for the development of a rapid non-destructive method to measure carotenoids and chlorophylls in berries which in turn can predict optimal ripeness. Furthermore, since carotenoids are the precursors to C13- norisoprenoid aroma compounds in wine a preview of the potential contribution of these aromas to wine might be evaluated. Further research is necessary to investigate the possibility of building and validating such models. / AFRIKAANSE OPSOMMING: Vorige navorsing het getoon dat karotenoïede die voorlopers is van C13-norisoprenoïed aromaverbindings in wyn. C13-norisoprenoïede het lae drempelwaardes in wyn, met β- damassenoon en β-jonoon as die prominentste C13-norisoprenoïede wat ‘n bydrae tot die heuning en blomagtige aroma van die wyn maak. Chlorofil en sy derivate is ook reeds in wyn bespeur, met die potensiaal om voorlopers van aromaverbindings te wees. Buiten die bydrae van hierdie pigmente tot wynaroma en -kwaliteit is hulle ook belangrike rolspelers in fotosintese en kom hulle wydverspreid in plante en plantprodukte voor. Die vernaamste funksies van hierdie pigmente in plante is om lig te versamel en om as beskerming teen lig op te tree. Navorsing het getoon dat omgewingstoestande, klimaat, ligblootstelling van die trosse en grondwatertekorte die karotenoïedinhoud van druiwekorrels beïnvloed. Verder is ook getoon dat die konsentrasie van karotenoïede en chlorofille tussen kultivars verskil. Geen navorsing is al in hierdie opsig op Merlot-druiwekorrels gedoen nie. Met hierdie aspek in gedagte was die doelwit van hierdie studie om die effek van groeikrag en grondwaterinhoud op die evolusie van karotenoïede en chlorofille tydens die rypwording van druiwekorrels van die cv. Merlot te evalueer. Wanneer mens egter kyk na die metodes waarvolgens die karotenoïede en chlorofille in korrelweefsel geanaliseer word, is daar geen geredelik beskikbare metodes nie. ‘n Ekstraksiemetode om die karotenoïed- en chlorofilprofiel van geliofiliseerde weefsel van onryp (groen) tot ryp (rooi) Merlot-bessies te identifiseer en kwantifiseer was dus nodig. In hierdie studie is die RP-HPLC metode van Taylor et al. (2006) vir karotenoïede en die ekstraksiemetode van Mendes-Pinto et al. (2004) aangepas om beide karotenoïede en chlorofille in geliofiliseerde druiweweefsel te analiseer. Die basislyn van die RP-HPLC metode het all karotenoïede en chlorofille en hul derivate geskei. Herwinning van die standaarde vanaf skynekstraksies was hoog, wat aandui dat die ekstraksieprosedure aanvaarbaar was. Ekstraksieherwinning wat in die matriks van die druiweweefsel getoets is, het egter minder belowende resultate getoon as gevolg van die hoë suurinhoud van die druifweefsel. Violaxantien, neoxantien en die chlorofille was veral sensitief vir toestande van lae pH, wat hulle afbreking gefasiliteer het. Die afbrekingsprodukte van hierdie verbindings onder suurtoestande is geïdentifiseer as feofitien a en b, chlorofillied a, pirofeofitien b, cis-violaxantien, cis-neoxantien, neochroom, mutatoxantien en luteoxantien. Daar is ‘n moontlikheid dat sommige afbreekprodukte reeds in die weefsel teenwoordig was as gevolg van liofilisering (aangesien die water in die korrel reeds verwyder was en die suur gekonsentreerd was). Meer werk is nodig om die effek van liofilisering en berging op die samestelling van druifweefsel van verskillende rypheid te bepaal. Die ekstraksiemetode vir druifkorrelweefsel op verskillende stadia van rypwording moet ook verder geoptimaliseer word om weefselsuurheid doeltreffend te neutraliseer, sonder om die ekstraksie van karotenoïede noemenswaardig te kompromitteer, veral in groen korrelweefsel. Die vraag of cis-isomere en chlorofil afbreekprodukte natuurlik in die druifkorrels teenwoordig is en of hulle tydens monsterneming en prosessering gevorm word, kon nie in hierdie studie beantwoord word nie. Hierdie studie het bevestig dat karotenoïede en chlorofille oor die algemeen op ‘n korrel (μg/korrel) en konsentrasie (μg/g) basis afneem vanaf deurslaan tot oes. Hierdie studie het nie daarin geslaag om te toon dat groeikragverskille vanaf voor-deurslaan (ertjiekorrelgrootte) tot oes ‘n effek het op die tempo van sintese/afbreking van karotenoïede, chlorofil en ander rypwordingsparameters nie, naamlik op appelsuur, totale glukose en fruktose, totale tannien en totale antosianien. Daar is ook in hierdie studie geen noemenswaardige effek van grondwaterinhoud op karotenoïede, chlorofille en rypheidsparameters gevind nie, heel moontlik as gevolg van die feit dat hoë grondwaterkapasiteit in die laer grondlae gevind is, wat betekenisvolle verskille in wingerdwaterstatus kon verhoed het. Eksperimentele persele wat gekies is vir groeikragverskille op grond van genormaliseerde verskil plantegroei indeks (NDVI) beelde, snoeimassa en grondwatermetings met ‘n neutronvogmeter het net in die eerste 30 cm van die grond noemenswaardige verskille in grondwaterinhoud getoon vir die rypwordingseisoene wat bestudeer is. Voor-sonopkoms plantwaterpotensiaalmetings het egter aangedui dat geen van die eksperimentele wingerdstokke ernstige waterstres ervaar het nie. Sulke stres is voorheen aangedui om ‘n effek op die karotenoïedinhoud van druiwe te hê. Die karotenoïed 5,8-epoksi--karoteen is vir die eerste keer in druiwe gekwantifiseer en verteenwoordig ‘n noemenswaardige hoeveelheid van die totale karotenoïede wat met oes teenwoordig is. Al die karotenoïede en chlorofille behalwe -karoteen blyk sensitief vir seisoenale verskille in klimaatstoestande te wees. Luteïen en β-karoteen was die volopste karotenoïede in die Merlot-druifkorrels, tesame met chlorofil a, vir beide seisoene wat bestudeer is. Die waardes van hierdie karotenoïede was ook goed gekorreleer met vorige navorsing. Chlorofil a is egter in baie groter hoeveelhede in Merlot-korrels gevind in vergelyking met dít wat in die data gerapporteer is. Die rede hiervoor is moontlik dat die chlorofil-afbreekprodukte in hierdie studie in die berekening van chlorofil a ingesluit is. Meerveranderlikeontleding het belowende voorlopige voorspellingsmodelle getoon (met korrelasiewaardes van meer as 0.8 vir beide die seisoene wat geanaliseer is) vir die voorspelling van die konsentrasie van rypheidsparameters (glukose, fruktose, appelsuur, totale tanniene en antosianiene) met karotenoïed- en chlorofilinhoud. Hierdie resultaat beklemtoon die geleentheid vir die ontwikkeling van ‘n vinnige, nie-destruktiewe metode om karotenoïede en chlorofille in korrels te meet, wat op sy beurt optimate rypheid kan voorspel. Aangesien karotenoïede die voorlopers van C13-norisoprenoïed aromaverbindings in wyn is, kan ‘n voorskou van die potensiële bydrae van hierdie aromas tot wyn moontlik verder evalueer word. Verdere navorsing is nodig om die moontlikheid van die bou en geldigheidsbepaling van sulke modelle te ondersoek.

Thesis (MScAgric (Viticulture and Oenology. Wine Biotechnology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The Vitis vinifera L. carotenoid cleavage dioxygenase 1 gene (VvCCD1) is a member of a structurally conserved gene family encoding enzymes that cleave multiple carotenoid substrates to form apocarotenoids. Carotenoid pigments are synthesised in the chloroplast where they are primarily involved in light harvesting and photo-protection during photosynthesis while apocarotenoids fulfill diverse roles that range from pollinator attractants to phytohormones. CCD1 cleaves carotenoids at specific double bond sites producing volatile apocarotenoids. These CCD1-derived apocarotenoids typically possess a fruity and floral aroma, thus making them desirable targets for metabolic engineering. CCD1 orthologues are highly homologous and have been isolated and characterised from a number of plant species, including Arabidopsis, tomato, rose, petunia, and grapevine. VvCCD1 is localised to the cytosol and has been shown in vitro to cleave zeaxanthin and lutein resulting in 3-hydroxy-β-ionone. Expression of VvCCD1 increases during berry ripening, peaking at véraison. Due to the impact that VvCCD1 potentially has on the flavour and aroma of grape berries and therefore wine, this study aimed to characterise the specific enzyme action as well as the biological role that this enzyme plays in grapevine. Expression of VvCCD1 in carotenoid-accumulating Escherichia coli strains demonstrated cleavage of β-carotene at the 9,10 (9’,10’) position forming β-ionone; and lycopene at the 5,6 (5’,6’) and 9,10 (9’,10’) position, forming 6-methyl-5-hepten-2-one and pseudoionone, respectively. A transgenic grapevine population with modified VvCCD1 expression was generated and genetically and metabolically characterised. The transgenic population consisted of lines in which VvCCD1 was either overexpressed or silenced. Expression analysis of stable transformants showed a 12-fold range of VvCCD1 expression relative to the wild-type. HPLC analysis of the photosynthetic pigment content of the transgenic population necessitated the development and optimisation of a method for the extraction of pigments, specifically from grapevine. A number of parameters were identified and optimised, resulting in a method that provides accurate quantification of photosynthetic pigments from grape berries and leaves. Absolute quantification of the following major photosynthetic pigments present in grapevine is now possible: chlorophyll a, chlorophyll b, lutein, -carotene, zeaxanthin, antheraxanthin, violaxanthin and neoxanthin. Data suggest that various levels of molecular control regulate carotenoid cleavage and apocarotenoid biosynthesis. The majority of lines stably transformed with a VvCCD1 overexpression cassette exhibit post-transcriptional gene silencing. Expression analysis in these lines demonstrated that, despite the additional contribution of transgene-derived VvCCD1 transcripts, the total VvCCD1 transcript levels were not significantly higher than in wild-type lines. In lines where transgenic manipulation of VvCCD1 expression was successful, subsequent analysis of carotenoids and apocarotenoids in leaf tissue showed no correlation between the measured metabolites and gene expression. The in planta action of VvCCD1 is presumably distinct from the observed in vitro activity due to the strict compartmentalisation required in photosynthetic leaf tissue preventing access of cytosolic VvCCD1 to the chloroplastic carotenoids. Future studies on reproductive organs (grape berries) from the transgenic lines generated in this study will be of great importance in further elucidation of the in planta function of VvCCD1. / AFRIKAANSE OPSOMMING: Die Vitis vinifera L. “carotenoid cleavage dioxygenase” 1 geen (VvCCD1) behoort aan ‘n geenfamilie wat struktureel gekonserveerd is en kodeer vir ensieme wat verskeie karotenoïed substrate afbreek om apokarotenoïede te vorm. Karotenoïed pigmente word in die chloroplaste gesintetiseer waar hulle primêr betrokke is by lig-insameling, sowel as beskerming tydens fotosintese, terwyl apokarotenoïede diverse funksies in die plant verrig wat strek van aantrekking van stuifmeelverspreiders tot phytohormone. CCD1 breek karotenoïede by spesifieke dubbelbindingsetels af om vlugtige apokarotenoïede te vorm. Die apokarotenoïede wat van CCD1 afkomstig is besit tipies vrugtige en blomagtige aromas wat hul gesogte teikens maak vir metaboliese manipulering. CCD1 ortoloë is hoogs homoloog en is al geїsoleer en gekarakteriseer vanuit ‘n verskeidenheid plantspesies wat Arabidopsis, tamatie, roos, petunia en wingerd insluit. VvCCD1 is in die sitosol gelokaliseer en dit is vantevore gewys dat dit beide zeaxanthin en lutein in vitro kan afbreek om 3-hidroksi-b-ionoon te vorm. Die uitdrukking van VvCCD1 vermeerder tydens korrel rypwording en bereik ‘n maksimum tydens véraison. Weens die potensieële invloed vanVvCCD1 op die geur en aroma van druiwe, en dus wyn, is hierdie studie gerig op die karakterisering van die spesifieke ensiematiese aksie, sowel as die biologiese rol van hierdie ensiem in wingerd. Uitdrukking van VvCCD1 in Escherichia coli rasse wat karotenoïede versamel het getoon dat β-karoteen by die 9,10 (9’,10’) posisie afgebreek word om β-ionoon te vorm, en likopeen by die 5,6 (5’,6’) en 9,10 (9’,10’) posisie om onderskeidelik 6-metiel-5-hepteen-2-oon en pseudo-ionoon te vorm. ‘n Transgeniese wingerd populasie is gegenereer met gewysigde VvCCD1 uitdrukking en is geneties en metabolies gekarakteriseer. Die transgeniese populasie het bestaan uit lyne waar VvCCD1 óf ooruitgedruk óf afgereguleer is. Uitdrukkings analise van die stabiele transformante het ‘n 12-voudige reeks van VvCCD1 uitdrukking getoon, relatief tot die wilde tipe. HPLC analise van die fotosintetiese-pigment inhoud van die transgeniese populasie het die ontwikkeling en optimisering van ‘n wingerd-spesifieke metode vir die ekstraksie van pigmente genoodsaak. ‘n Aantal parameters is geïdentifiseer en geoptimiseer, en het gelei tot ‘n metode wat akkurate kwantifisering van fotosintetiese pigmente in druiwe en wingerdblare kan lewer. Absolute kwantifisering van die volgende belangrike fotosintetiese pigmente aanwesig in wingerd is nou moontlik: chlorophyll a, chlorophyll b, lutein, -karoteen, zeaxantien, anteraxantien, violaxantien en neoxantien. Data dui aan dat verskeie vlakke van molekulêre beheer die afbreking van karoteen en die biosintese van apokarotenoïede reguleer. Die meerderheid van die lyne wat stabiel getransformeer is met ‘n VvCCD1 ooruitdrukkingskasset het na-transkripsioneleafregulering van die geen getoon. Uitdrukking analise van die lyne het gewys dat ten spyte van die addisionele transgeniese VvCCD1 transkripte, die totale VvCCD1 transkripvlakke nie beduidend hoër was as dié van die wilde-tipe lyne nie. In die lyne waar transgeniese manipulasie van VvCCD1 uitdrukking wel suksesvol was, het verdere analise van die karotenoïed en apokarotenoïed vlakke in blaarweefsel geen korrelasie getoon tussen die metaboliete en VvCCD1 uitdrukking nie. Die in planta aktiwiteit van VvCCD1 is vermoedelik anders as die in vitro aktiwiteit weens die streng kompartementalisering benodig in fotosintetiese blaarweefsel, wat verhoed dat die sitosoliese VvCCD1 toegang het tot die chloroplastiese karotenoïede. Toekomstige bestudering van die reproduktiewe organe (druiwe) van die transgeniese lyne wat in hierdie studie gegenereer is sal belangrik wees in die verdere verduideliking van die in planta funksie van VvCCD1.

Thesis (MScAgric) -- Stellenbosch University, 2005. / ENGLISH ABSTRACT: Winemakers or producers are under constant pressure to reduce the operational costs for the production of wine. The reason for this being threefold: Firstly, the number of cellars and estates locally, and internationally, has grown immensely. Thus, the competition on both the national and international front has put producers under pressure to reduce their production cost in order to survive the explosion of brand possibilities on the consumer's horizons. Secondly, the exchange rate has been one of the most unpredictable variables which highlight the importance of scenario planning and sufficient financial planning in order to overcome significant exchange rate fluctuations which may cause financial strain for the business. Thirdly, the benefits of using expensive oak barrels for the maturation of premium quality wines are undisputable. These benefits include the clarification and decarbonation of wines, decrease in the astringency of tannins ("softening of tannins"), the evolution of colour, providing complementary oak aromas which increase the complexity and finesse of these wines and stabilising the colloid structure of the maturing wine. The greatest disadvantages remain nevertheless that it is a costly and labour intensive operation. Oak is an essential part of the flavour profile of many premium quality wines, and there is still a growing market demand for these wines. The use of oak barrels for the maturation of premium red wines, incorporates a specific flavour dimension to the wine (and adding value), has been the traditional way of storing wines. Well known cellars and Estates all over the world have build remarkable profiles and identities for their brands. To alter any principles regarding the use of oak will alter the style of the wines and will beyond any doubt influence their brand image negatively. Chapter 1 gives an introduction and the main aims of the study. The phenolic composition of grapes and oak are a complex mixture of different molecules which are discussed in Chapter 2. These include those responsible for the colour (anthocyanins), taste (mainly the tannins) and aroma of the wine. The composition of the oak barrel can be influenced by its origin, seasoning of the oak, toasting of the staves, age of the barrel etc. These factors all affect the chemical composition of the oak (lactones, volatile phenols, carbohydrate volatiles, hydrolysable tannins etc.) and ultimately, the wine. The chemical reactions taking place in wine during ageing are also complex, which makes maturation and research of wine in oak a complex business. The challenge, thus, developed to sustain the flavour profiles (oak attributes) and to reduce the operational costs, without influencing the identity or profile of the brand negatively. The use of oak derived products like chips, dust, blocks, staves, balls and even extracts was proposed, although it is considered by-products of the cooperage profession. Some of the major disadvantages of the use of oak derived products still remain the limited control over the production process. This may lead to inconsistency in the quality of these products. Nevertheless, the use of oak derived products and the availability of these products have grown significantly and with it a need for research on this field. Chapter 3 address the results obtained from the maturation of Pinotage, which is uniquely South African, and Shiraz wines, in different oak type barrels (French vs. American vs. Russian), as well as treatments with various oak derived products, and the influence of these oak products on the evolution of colour, phenolic development and quality of the wines during ageing. The results obtained in this project correlated with findings in the literature. The colour density, percentage of red pigment colour and S02 resistant pigments increased, especially in the first three to six months during ageing in barrels as a result of ellagic tannin extraction from the barrels and polymerisation reactions, but decreased later as maturation progresses as a result of precipitation. In some cases the use of oak increased the colour density significantly with almost 40%. The colour density, total red pigment colour and total phenolic composition decreased during bottle maturation as a result of polymerisation. No significant colour differences between the barrel types could, however, be detected. The use of oak derived products showed the same tendencies for all colour dimensions, although no significant differences could be detected between the treatments. The most significant difference was that new oak barrels contributed more to the development of colour compared to the oak treatments. The Gelatine index gives an indication of the degree of polymerisation of tannins; higher values will indicate tannins which are highly reactive and will cause an astringent mouth feel. The values should decrease as maturation progresses and tannins polymerise. Little differences between barrel types (French vs. American vs. Russian) were found in the one Shiraz, but in the two Pintage wines the index was the lowest in the wines matured in French oak after 36 months bottle ageing. Sensorial tests indicated little quality differences after 36 months between the different oak types The American oak barrels had, in general, a more "oaky bouquet", even after 36 months in the bottle. Pinotage matured with different alternative oak products showed that chips added to barrels tended to give a higher oak aroma, with a lower fruit compared to the other treatments. The same wine matured in new barrels, as expected, also had a very high oak aroma compared to the same wine matured in older barrels. This led to a higher fruit perception in the latter wines. Lees contact is a practice more commonly used in the production of white wines, but may be a dangerous practice in the production of red wines. Chapter 4 reports on the effect of lees contact during ageing of red wine on the micro flora and colour after 12 month maturation. No significant differences in microbial analysis were detected during of barrel maturation between the wines matured in the lees and the filtered wines for acetic acid, yeast and lactic acid bacteria. The initial pH differences during cold maceration and fermentation, however, did influence these numbers, with higher numbers being observed at higher pH values. However, colour differences could be detected. The concentration of yellow brown pigments (measured at 420 nm) was lower in the lees matured wines than in the filtered· wines which underwent malolactic fermentation in the barrel. Other colour differences that could be detected were higher colour density and total red pigment colour in wines as a result of longer skin contact (due to slower alcoholic fermentation rate). Thus, manipulation of the skins during alcoholic fermentation, the use of barrels and/or oak derived products in various stages of vinification and maturation of wines and additional practices as maturation on lees may be thus be used to set a certain style of wine which meet a specific market demand, trend or style. Chapter 5 summarises the results obtained and future research to be done on wood and wine. This study, however, clearly showed that the origin and oak type does not influence the colour as much as the aroma and taste of red wine under South African conditions. / AFRIKAANSE OPSOMMING; Wynmakers of produsente word onder gedurige druk geplaas om die produksiekoste van wyn te verlaag. Die redes hiervoor is drieledig: Eerstens het die getal kelders en landgoedere op nasionale en internasionale vlak geweldig toegeneem. Dus, die kompetisie op beide nasionale en internasionale gebied plaas produsente onder druk om die produksie koste van die wyn te verminder om sodoende finansieel die ontploffing van nuwe moontlike wyne op die horison van die verbruiker te oorleef. Tweedens, die wisselkoers was altyd een van die meer onvoorspelbare veranderlikes wat die belangrikheid van scenario-beplanning en weldeurdagte finansiele beplanning beklemtoon om sodoende groat veranderinge in die wisselkoers, wat moontlike finansiele druk in die besigheid mag veroorsaak, te oorkom. Derdens, een van die grootste uitgawes in die produksie proses van is die verouderingskomponent van kwaliteitswyn. Die voordele van die gebruik van eikehout vate in die verouderingsproses van rooiwyne is welbekend. Hierdie voordele sluit in die suiwering van die wyn in terme van soliede partikels , dekarbonisering (C02-ontgasting}, afname in die vrank smaak ("sagtheid van die tanniene), die ontwikkeling van die kleur van die wyn, toevoeging van komplementere hout boeketstowwe wat bydrae tot die kompleksiteit van die wyn, asook die stabilisering van die kollo"idale struktuur van die wyn. Die grootste nadeel bly, nieteenstaande, die geweldige koste verbonde aan vate, asook die hantering en onderhoud daarvan. Eike hout verwante boeketstowwe is 'n onmisbare komponent van die aroma profiel van baie kwaliteitswyne. Daar is 'n groeiende mark vir hierdie tipe wyne. Die gebruik van eikehout vate vir die veroudering van kwaliteitswyne, behalwe die bydrae van belangrike geurstowwe (een waarde), was nog altyd 'n tradisionele stap in die proses. Beroemde kelders reg oor die wereld het uitmuntende mark identiteite vir hulle self geskep, asook 'n "spesifieke identiteit" vir hulle wyn. Om enige beginsels aangaande die gebruik van eikehout te verander, sal sander twyfel die wynstyl verander en moontlik 'n negatiewe effek op die kelder se identiteit he. Hoofstuk 1 gee 'n inleiding en die hoof doelstellings van die studie. Die fenoliese samestelling van druiwe en eikehout bestaan uit 'n komplekse mengsel van verskillende molekules wat in Hoofstuk 2 beskryf word. Hierdie sluit in daardie verantwoordelik vir die kleur (antosianiene), die smaak (hoofsaaklik tanniene) en die aroma van die wyn. Die samestelling van die eikevat kan beinvloed deur die oorsprong, veroudering van die hout, roostering, ouderdom van die vat ens. Hierdie faktore beinvloed almal die samestelling van die houtvat (laktone, vlugtige fenole, hidroliseerbare tanniene ens.) en uiteindelik, die wyn. Die chemiese reaksies wat plaasvind tydens die veroudering van wyn is ook kompleks, wat die veroudering en navorsing van wyn in vate 'n komplekse proses kan maak. Die uitdaging, dus, het ontstaan om die organoleptiese profiel van die wyn (eikehout boeketstowwe) te behou en terselftertyd die produksiekoste van die wyn te verlaag. Die gebruik van eikehout verwante produkte soos skaafsels, blokkies, stawe en balke en selfs eikehout ekstrakte is aanbeveel, alhoewel dit gesien word as afvalprodukte van die kuiperye Een van die grootste nadele van eikehout alternatiewe produkte is egter die beperkte kwaliteitskontrole oor die produksieproses. Dit mag lei tot wisselvalligheid in die kwaliteit van hierdie produkte. Nieteenstaande het die gebruik van eike houtverwante produkte en die beskikbaarheid van hierdie produkte geweldig toegeneem en tesame daarmee die behoefte aan navorsing hieroor. Hoofstuk 3 bespreek resultate van die gebruik van verskillende eikehout tipe vate (Frans vs Russies vs Amerikaans), asook die gebruik van eikehout verwante produkte, op die kleur ontwikkeling, fenoliese samestelling en kwaliteit van Pinotage (eie aan Suid-Afrika) en Shiraz wyne gedurende vat en bottel veroudering. Die ontwikkeling van kleur het verskeie unieke dimensies en resultate wat verkry is in hierdie projek stem ooreen met literatuur. Die kleurdigtheid, persentasie rooi pigment en 802 weerstandbiedende pigmente het toegeneem met veroudering in houtvate (veral in die eerste drie tot ses maande) as gevolg van ellagitanniene wat geekstraeer word en gepolimerisasie, maar het later gedurende veroudering afgeneem as gevolg van presipitasie reaksies. In sekere gevalle het die kontak met hout die kleurdigtheid met tot 40% vermeerder. Die kleurdighteid, totale rooi pigmente en totale fenole het tydens bottelverouding afgeneem a.g.v. polimerisasie. Geen merkwaardige verskille kon egter tussen die verskillende vattipes gevind word nie. Verskille tussen die houtverwante produkte was ook klein en het diesefde tendense getoon as die vate. Nuwe vate se impak op die kleurprofiel en ontwikkeling van verouderde rooiwyne was egter meer beduidenswaardig as die gebruik van gebruikte vate en behandelings met eikehout verwante produkte. Die gelatien indeks verwys na die toestand van polimerisasie van tanniene. Hoer waardes kan verwag word in jong wyne en dui op hoogs reaktiewe tanniene. Die waarde sal afneem soos tanniene polimere vorm met veroudering en sal dus 'n veel minder vrank mondgevoel tot gevolg he. Klein verskille tussen die vat tipes (Frans vs Amerikaans vs Russies) is opgemerk in die een Shiraz, maar in die twee Pinotage wyne was die indeks die laagste in die wyne verouder in Franse eikehout na 36 maande se bottelveroudering. Sensoriese toetse het aangedui dat daar klein verskille gevind is tussen die verskillende eiketipes. Die wyn verouder in Amerikaanse eik het, in die algemeen, 'n sterker eikehoutkarakter gehad na 36 maande bottelveroudering. Wyn verouder met verskillende alternatiewe houtprodukte het aangetoon dat eikehouskaafels in vate 'n sterker eikehoutkarakter aan die wyn gegee het met 'n laer vrugtige aroma in vergelyking met die ander behandelings. Dieselfde wyn verouder in nuwe vate het oak, soos verwag, 'n sterk hout boeket gehad in vergelyking met die verouder in ouer vate. Dit het dan oak gelei dat laasgenoemde wyne 'n sterker vrug aroma gehad het. Veroudering van wit wyne op moer is 'n algemene praktyk, alhoewel dit minder toegepas word op rooiwyne as gevolg van verwante gevare. Hoofstuk 4 bespreek die effek van moerkontak op die mikrobiese en kleursamestelling van rooiwyn tydens 12 maande se houtveroudering. Geen noemenswaardige verskille is egter verkry tussen die wyne verouder op die moer en die filtreerde wyne vir asynsuur-, melksuurbateriee en gisgetalle nie. Aanvanklike pH verskille tydens koue masserasie en alkoholiese fermentasie het egter hierdie getalle beinvloed, met hoer ·getalle verkry in die hoer pH wyn. Die wyne wat appelmelksuurgisting in die vate ondergaan het en verouder is op die moer het egter 'n laer konsentrasie geelbruin pigmente (gemeet by 420 nm) as die gefiltreerde wyne. Ander kleurverskille sluit in hoer kleurdigtheid en totale rooi pigmente as gevolg van langer dopkontak (stadiger alkoholiese fermentasie). Manipulering van die doppe voor en tydens alkoholiese gisting, die gebruik van eikehoutvate of eikehoutverwante produkte, of kombinasies daarvan tydens verskillende produksie fases en ander praktyke soos moer kontak, kan dus gebruik word am 'n sekere styl wyn op markversoek daar te stel. Hoofstuk 5 som die resultate op, asook toekomstige navorsingsmoontlikhede wat op die gebied van hout en wyn gedoen kan word. Hierdie studie het egter duidelik aangedui dat die eikehout oorsprong en tipe die kleur nie so baie beinvloed soos die aroma en smaak van die wyn onder Suid-Afrikaanse kondisies nie.