Levoglucosan is the major anhydrosugar component of bio-oil produced by fast pyrolysis. Previous research has shown that levoglucosan yield can be greatly increased if a mild acid pretreatment is applied to demineralize the feedstock prior to pyrolysis. The interest in levoglucosan production is that it provides a route to production of monomeric sugars, primarily glucose, which can be utilized to produce biochemically derived fuels (ethanol, butanol, etc.) In one study, four different lignocellulosic biomass were subjected to pyrolysis as feedstocks to produce bio-oils via fast pyrolysis in a 7 kg/h feed rate auger reactor. Feedstocks were pretreated with dilute phosphoric acid and bio-oils were produced and analyzed to compare the bio-oil characteristics from both untreated and treated feedstocks. The results shown in this study strongly indicate that the ash content and alkali metal content are very important parameters which can greatly affect the yield and many properties of bio-oils produced during fast pyrolysis. The dilute acid pretreatment performed in this study significantly reduced the total ash content and alkali metal content in the feedstocks, resulting in a great increase in the bio-oil and levoglucosan yields. It was also shown that dilute acid pretreatment was more effective in treating herbaceous feedstocks than woody biomass in terms of increasing bio-oil production yield and improving bio-oil properties. In one study, bio-oil composed of high levoglucosan concentration was produced via fast pyrolysis of dilute acid pretreated loblolly pine wood in an auger reactor. Water-to-bio-oil ratio, temperature, and time were selected as the three parameters to investigate the optimal condition for extracting the maximum amount of levoglucosan from the bio-oil. The optimal condition for levoglucosan extraction determined was 1.3 : 1 (water-to-bio-oil ratio), 25 oC, and 20 min, producing a levoglucosan yield of 12.7 wt %. The final study developed a new method based on pyrolysis of dilute acid pretreated loblolly pine wood and modification of the pyrolysis process. This new method resulted in a significant 30.7 wt % increase in levoglucosan concentration in the bio-oil organic portion. The results indicated that this method successfully suppressed the levoglucosan decomposition during fast pyrolysis.

The US Department of Energy has set an ambitious goal of replacing 30% of current petroleum consumption with biomass and its products by the year 2030. To achieve this goal, various systems capable of handling biomass at this magnitude have to be designed and built. The transportation system for a cotton gin was studied and modeled with the current management policy (FIFO) used by the gin to gain understanding of a logistic system where the processing plant (gin) pays for the transportation of the feedstock. Alternate management policies for transporting cotton modules showed significant time savings of 24% in days-to-haul. To design a logistics system and management strategy that will minimize the cost of biomass delivery (round bales of switchgrass), a seven-county region in southern Piedmont region of Virginia was selected as the location for a 50 Mg/h bioprocessing plant which operates 24 h/day, 7 days/week. Some of the equipment are not be commercially available and need to be developed. The transport equipment (trucks, loaders and unloaders) was defined and the operational parameters estimated. One hundred and fifty-five secondary storage locations (SSLs) along with a 3.2-km procurement area for each SSL were determined for the region. The travel time from each SSL to the plant was calculated based on a network flow analysis. Seven different policies (strategies) for scheduling loaders were studied. The two key variables were maximum number of trucks required and the maximum at-plant inventory. Five policies were based on "Shortest Travel Time - Longest Travel Time" allocation and two policies were based on "Sector-based" allocation. Policies generating schedules with minimum truck requirement and at-plant storage were simulated. A discrete event simulation model for the logistic system was constructed and the productive operating times for system equipment and inventory was computed. Lowest delivered cost was $14.68/Mg with truck cost averaging $8.44/Mg and loader cost averaging $2.98/Mg. The at-plant inventory levels were held to a maximum of 390 loads. The loaders operated less than 9,500 hours and the unloaders operated for a total of 2,700 hours for both systems simulated. / Ph. D.

The production of biofuels and biobased products from low-cost abundant renewable non-food lignocellulosic biomass will be vital to sustainable development because it will bring benefits to the environment, the economy, and the national security. The largest technical and economic challenge for emerging biorefineries is cost-effective release of fermentable sugars from recalcitrant structure of lignocellulosic biomass. Cellulose- and organic-solvent-based lignocelluloses fractionation (COSLIF) technology was employed to overcome biomass recalcitrance. Surface response methodology (SRM) showed that optimal COSLIF pretreatment conditions were 85% (w/v) H₃PO₄ and ~50 °C, regardless of moisture contents in biomass from 5-15% (w/w) for common reed. Under these conditions, the pretreated biomass was hydrolyzed fast with high glucan digestibilities at low enzyme loadings (i.e., one FPU of cellulase per gram of glucan). Crystallinity index (CrI) measurements by X-ray diffraction (XRD) and cross polarization/magic angle spinning (CP/MAS) ¹³C nuclear magnetic resonance (NMR), and cellulose accessibility to cellulase (CAC) determinations of COSLIF-pretreated biomass confirmed that highly ordered hydrogen-bonding networks in cellulose fibers of biomass were disrupted through cellulose dissolution in a cellulose solvent. This disruption of hydrogen bonding networks among cellulose chains resulted in a drastic increase in CAC values. Fourier transform infrared (FTIR) analyses on COSLIF-pretreated biomass revealed conformational changes in specific hydrogen bonding among cellulose chains due to COSLIF. While CrI is believed to be a key substrate characteristic that impacts enzymatic cellulose hydrolysis, studies in this thesis showed CrI values varied greatly depending on measurement techniques, calculation approaches, and sample preparation conditions. A correlation between CAC values and glucan digestibility of pretreated biomass showed that substrate accessibility is a key substrate characteristic impacting enzymatic cellulose hydrolysis. In summary, COSLIF can effectively overcome biomass recalcitrance. The resulting pretreated biomass has high CAC values, resulting in fast hydrolysis rates and high enzymatic glucan digestibilities of COSLIF-pretreated biomass at low enzyme usage. / Ph. D.

Non-ionic surfactants are known to enhance the biochemical conversion of lignocellulosic (LC) biomass to bioethanol. Their mechanisms of action, however, are incompletely understood. This research was conducted to elucidate the effects of the non-ionic surfactant Tween 80 on the enzymatic hydrolysis of cellulose and LC substrates. Model cellulose substrates were prepared from cellulose nanocrystals (CNCs) obtained by sulfuric acid hydrolysis of wood pulp. Two methods were developed for the removal of the sulfate groups on the CNCs, resulting from the use of sulfuric acid in their preparation. The effect of sulfate groups, which may be introduced into LC biomass during pretreatment with sulfuric acid, on the enzymatic hydrolysis of cellulose was studied with model cellulose substrates prepared from CNCs with different sulfate group densities. Adsorption of cellulases onto sulfated substrates increased with increasing sulfate group density but their rate of hydrolysis decreased. The decrease indicated an inhibitory effect of sulfate groups on the enzymatic hydrolysis of cellulose, possibly due to non-productive binding of the cellulases onto the substrates through electrostatic interactions instead of their cellulose binding domains. The effect of Tween 80 on the adsorption of cellulases onto lignin, often present as residual lignin in pretreated biomass, was studied with model lignin substrates, prepared from kraft lignin, organosolv lignin, and milled wood lignin. Cellulases appeared to adsorb onto the lignin substrates via both hydrophobic and polar interactions. Tween 80 molecules on the lignin substrates seemed to hinder cellulase adsorption via hydrophobic interactions and reduced the adsorption rate. Finally, the effects of lignin and Tween 80 on the enzymatic hydrolysis of cellulose and LC substrates were studied. Lignin hindered both the adsorption of cellulases onto the substrates and the enzymatic hydrolysis of the substrates. Tween 80 was found to form surfactant–protein complexes with cellulases in solution without compromising cellulase activity. Either substrate-adsorbed or in solution, Tween 80 had no effect on the hydrolysis of cellulose by cellulases. Substrate-adsorbed Tween 80 increased the apparent enzymatic hydrolysis rates of LC substrates but the ability of Tween 80 to increase their apparent hydrolysis rate depended strongly on their structural properties and the chemical properties of the lignin. Hence, Tween 80 may be able to mitigate the inhibitory effect of lignin on the enzymatic hydrolysis of pretreated biomass. / Ph. D.

The southern pine beetle (SPB) poses a significant threat to pine forests of the southeastern US. Pre-commercial thinning (PCT) is a commonly used silvicultural practice to mitigate and prevent SPB spread in young southern pine stands. Typically, PCT represents an added management cost to landowners and thinned material is not utilized for forest products. Increased demand for woody biomass energy may provide landowners and harvesting contractors an opportunity to utilize PCT residues as a woody biomass energy feedstock, which may wholly or partially offset PCT costs. However, little information is available regarding harvestable biomass quantities in PCT stands and few studies have assessed harvesting productivity and costs in very young pine stands. To develop estimates of biomass abundance in PCT candidate stands, loblolly pine (Pinus taeda) stands aging 5 to 12-years old, and enrolled in the Virginia Department of Forestry Pine Bark Beetle Prevention Program (VDOF PBBPP), were inventoried across the Piedmont and Coastal Plain regions of Virginia. To attain productivity and cost estimates of utilizing small-diameter stems for woody biomass energy, a biomass harvesting case study was then conducted on a 15-year old loblolly pine stand. Results of the inventory and case study indicate that stands at the upper age limit for the PCT program may contain harvestable quantities of biomass (39.63 green tons/acre), although high harvesting costs ($23.46/green ton) relative to regional delivered biomass prices may limit the economic feasibility of utilizing PCT biomass for energy. / Master of Science

<p dir="ltr">Feedstock variability represents a challenge in the adoption of lignocellulosic biomass for biofuels and biochemicals production, due to the differences in critical chemical and physical properties like lignin content, and water absorption respectively. Thus, difficult continuous manufacturing processes in biorefineries, hinder the transition from liquid feedstocks to renewable materials that consisting of solid particles. Modeling of flow properties based on rheological measurements of treated biomass is a quantitative metric for identifying if different feedstocks form pumpable slurries. Additionally, the correlation of yield stress to physical and chemical properties gives a measure that accounts for the variability in the processing design. This research models rheological properties and relates these to compositional data from different non-pretreated fractions of corn stover biomass slurries. Slurries were formed with solids concentrations of 300 g/L in a 6 hours fed-batch process using the commercial enzymes Celluclast 1.5L or Ctec-2 at 1FPU/g or 3 FPU/g of dry solids, basis to enable the liquefaction (i.e., slurry-forming) mechanism. We found that insoluble lignin content of the different fractions was related to water absorption in pellets and free water on slurries and that free water was a good indicator of the potential for a material to form slurry. Higher flowability (lower yield stress) was found at higher content of lignin, particularly for materials containing 26% lignin where yield stress was reduced to 254Pa when compared with mixtures of 14% lignin that presented yield stresses of around 4000 Pa. We show that rheology modeling linked to compositional characteristics for biomass slurries can be used to predict material flow behavior in a biorefinery to optimize and achieve high solids loadings that enhance the production of ethanol for biofuels. This insight and the ability to form high concentration slurries before pretreatment holds the potential to develop new processing strategies that could help to foster a more efficient and sustainable bio-based industry. </p>

Current carbon and bioenergy markets shifted the focus of typical forest attribute estimation from volume to biomass. We used multiple linear regression and the dataset collected as part of the National Scale Volume and Biomass modeling effort to develop biomass prediction models for Pinus taeda L., Pinus elliottii Engelm. var. elliottii, Pinus echinata Mill., and Pinus palustris Mill. In addition to utilizing traditional forest measurements such as diameter at breast height and total tree height, biomass was estimated as functions of volume, latitude, and longitude. We also evaluated the differences in wood density by geographic location for these species. The best results were obtained when models were fitted using the combined dataset and a log transformed model. Wood density estimates were improved by including latitude and longitude in the model. These findings will be useful to managers seeking improved biomass yield estimates and density by geographic regions.

Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In recent times, governments around the world have placed increasing focus on cleaner technologies and sustainable methods of power generation in an attempt to move away from fossil fuel derived power, which is deemed unsustainable and unfriendly to the environment. This trend has also been supported by the South African government, with clear intentions to diversify the country’s power generation by including, among others, biomass as a renewable resource for electricity generation. Woody biomass and associated forestry residues in particular, could potentially be used as such a renewable resource when considering the large amount of fast growing hardwood species cultivated in South Africa. Approximately 6.3 million ton of Eucalyptus grandis is sold annually for pulp production while a further 7 million ton of Eucalyptus species are sold as round wood. With these tree species reaching commercial maturity within 7 – 9 years in the South African climate, there is real potential in harnessing woody biomass as a renewable energy source. In this study, pyrolysis was investigated as a method to condense and upgrade E.grandis into energy and chemical rich products. The pyrolysis of E.grandis is the study of the thermal degradation of the biomass, in the absence of oxygen, to produce char and bio-oil. The thermal degradation behaviour of E.grandis was studied using thermo-gravimetric analysis (TGA) at the Karlsruhe Institute of Technology (KIT) in Germany and subsequently used to determine the isoconversional kinetic constants for E.grandis and its main lignocellulosic components. Slow, Vacuum and Fast Pyrolysis were investigated and optimised to maximise product yields and to identify the key process variables affecting product quality. The Fast Pyrolysis of E.grandis was investigated and compared on bench (KIT0.1 kg/h), laboratory (SU1 kg/h) and pilot plant scale (KIT10 kg/h), using Fast Pyrolysis reactors at Stellenbosch University (SU) in South Africa and at KIT in Germany. The Slow and Vacuum Pyrolysis of E.grandis was investigated and compared using a packed bed reactor at Stellenbosch University. The TGA revealed that biomass particle size had a negligible effect on the thermal degradation behaviour of E.grandis at a heating rate set point of 50 °C/min. It was also shown that increasing the furnace heating rates shifted the thermo-gravimetric (TG) and differential thermo-gravimetric (DTG) curves towards higher temperatures while also increasing the maximum rate of volatilisation. Lignin resulted in the largest specific char yield and also reacted across the widest temperature range of all the samples investigated. The average activation energies found for the samples investigated were 177.8, 141.0, 106.2 and 170.4 kJ/mol for holocellulose, alpha-cellulose, Klason lignin and raw E.grandis, respectively. Bio-oil yield was optimised at 76 wt. % (daf) for the SU1 kg/h Fast Pyrolysis plant using an average biomass particle size of 570 μm and a reactor temperature of 470 °C. Differences in the respective condensation chains of the various Fast Pyrolysis reactor configurations investigated resulted in higher gas and char yields for the KIT reactor configurations compared to the SU1 kg/h Fast Pyrolysis plant. Differences in the vapour residence time between Slow (>400 s) and Vacuum Pyrolysis (< 2 s) resulted in a higher liquid and lower char yield for Vacuum Pyrolysis. Local liquid yield maxima of 41.1 and 64.4 wt. % daf were found for Slow and Vacuum Pyrolysis, respectively (achieved at a reactor temperature of 450 °C and a heating rate of 17 °C/min). Even though char yields were favoured at low reactor temperatures (269 – 300 °C), the higher heating values of the char were favoured at high reactor temperatures (29 – 34 MJ/kg for 375 – 481 °C). Reactor temperature had the most significant effects on product yield and quality for the respective Slow and Vacuum Pyrolysis experimental runs. The bio-oils yielded for SP and VP were found to be rich in furfural and acetic acid. / AFRIKAANSE OPSOMMING: Regerings regoor die wêreld het in die afgelope tyd toenemende fokus geplaas op skoner tegnologie en volhoubare metodes van kragopwekking in 'n poging om weg te beweeg van fossielbrandstof gebasseerde energie, wat geag word as nie volhoubaar nie en skadelik vir die omgewing. Hierdie tendens is ook ondersteun deur die Suid-Afrikaanse regering, met 'n duidelike bedoeling om die land se kragopwekking te diversifiseer deur, onder andere, biomassa as 'n hernubare bron vir die opwekking van elektrisiteit te gebruik. Houtagtige biomassa en verwante bosbou afval in die besonder, kan potensieel gebruik word as so 'n hernubare hulpbron, veral aangesien ‘n groot aantal vinnig groeiende hardehout spesies tans in Suid-Afrika verbou word. Ongeveer 6,3 miljoen ton Eucalyptus grandis word jaarliks verkoop vir pulp produksie, terwyl 'n verdere 7 miljoen ton van Eucalyptus spesies verkoop word as paal hout. Met hierdie boom spesies wat kommersiële volwassenheid bereik binne 7 - 9 jaar in die Suid-Afrikaanse klimaat, is daar werklike potensiaal vir die benutting van houtagtige biomassa as 'n hernubare energiebron. In hierdie studie is pirolise ondersoek as 'n metode om E.grandis te kondenseer en op te gradeer na energie en chemikalie ryke produkte. Die pirolise van E.grandis is die proses van termiese afbreking van die biomassa, in die afwesigheid van suurstof, om houtskool en bio-olie te produseer. Die termiese afbrekingsgedrag van E.grandis is bestudeer deur gebruik te maak van termo-gravimetriese analise (TGA) by die Karlsruhe Instituut van Tegnologie in Duitsland en daarna gebruik om die kinetiese konstantes vir die iso-omskakeling van E.grandis en sy hoof komponente te bepaal. Stadige, Vakuum en Snel pirolise is ondersoek en geoptimiseer om produk opbrengste te maksimeer en die sleutel proses veranderlikes wat die kwaliteit van die produk beïnvloed te identifiseer. Die Snel Pirolise van E.grandis is ondersoek en vergelyk op bank- (KIT0.1 kg / h), laboratorium- (SU1 kg / h) en proefaanlegskaal (KIT10 kg / h) deur gebruik te maak van Snel pirolise reaktore by die Universiteit van Stellenbosch (US) in Suid-Afrika en die Karlsruhe Instituut van Tegnologie (KIT) in Duitsland. Die Stadige en Vakuum Pirolise van E.grandis is ondersoek en vergelyk met behulp van 'n gepakte bed reaktor aan die Universiteit van Stellenbosch. Die TGA studie het openbaar dat biomassa deeltjiegrootte 'n onbeduidende uitwerking op die termiese afbrekingsgedrag van E.grandis het by 'n verhittings tempo van 50 ° C / min. Dit is ook bewys dat die verhoging van die oond verwarming tempo die termo-gravimetriese (TG) en differensiële termo-gravimetriese (DTG) kurwes na hoër temperature verskuif, terwyl dit ook die maksimum tempo van vervlugtiging laat toeneem het. Lignien het gelei tot die grootste spesifieke houtskool opbrengs en het ook oor die wydste temperatuur interval gereageer van al die monsters wat ondersoek is. Die gemiddelde aktiveringsenergieë vir die monsters wat ondersoek is, was 177,8, 141,0, 106,2 en 170,4 kJ / mol, onderskeidelik vir holosellulose, alpha-sellulose, Klason lignien en rou E.grandis. Bio-olie opbrengs is geoptimeer teen 76 wt. % (DAF) vir die SU1 kg / h Snel Pirolise aanleg met behulp van 'n gemiddelde biomassa deeltjiegrootte van 570 μm en 'n reaktor temperatuur van 470 ° C. Verskille in die onderskeie kondensasie kettings van die verskillende Snel Pirolise aanlegte wat ondersoek is, het gelei tot hoër gas- en houtskool opbrengste vir die KIT reaktor konfigurasies in vergelyking met die SU1kg/h FP plant. Verskille in die damp retensie tyd tussen Stadige (> 400 s) en Vakuum pirolise (<2 s) het gelei tot 'n hoër vloeistof en laer houtskool opbrengs vir Vakuum Pirolise. Plaaslike vloeistof opbrengs maksima van 41,1 en 64,4 wt. % (daf) is gevind vir Stadig en Vakuum pirolise onderskeidelik, bereik by 'n reaktor temperatuur van 450 ° C en 'n verhittingstempo van 17 ° C / min. Selfs al is houtskool opbrengste bevoordeel by lae reaktor temperature (269 - 300 ° C), is die hoër warmte waardes van die houtskool bevoordeel deur hoë reaktor temperature (29 - 34 MJ / kg vir 375 - 481 ° C). Reaktor temperatuur het die mees beduidende effek op die produk opbrengs en kwaliteit vir die onderskeie Stadige Pirolise en Vakuum Pirolise eksperimentele lopies gehad. Die bio-olies geproduseer tydens Stadige en Vakuum Pirolise was ryk aan furfuraal en asynsuur.

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 (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Increased demand of petroleum, declining fossil fuel reserves, geopolitical instability and the environmentally detrimental effects of fossil fuels have stimulated research to search for alternative sources of energy such as plant derived biofuels. The main feedstocks for production of first generation biofuels (bioethanol) are currently sucrose and starch, produced by crops such as sugarcane, sugarbeet, maize, and cassava. The use of food crop carbohydrates to produce biofuels is viewed as competing for limited agronomic resources and jeopardizing food security. Plants are also capable of storing sugars in their cell walls in the form of polysaccharides such as cellulose, hemicelluloses and pectin, however those are usually cross-linked with lignin, making their fermentation problematic, and are consequently referred to as lignocellulosics. Current technologies are not sufficient to degrade these cell wall sugars without large energy inputs, therefore making lignocellulosic biomass commercially unviable as a source of sugars for biofuel production. In the present study genes encoding for enzymes for cellulosic, hemicellulosic and starch-like polysaccharides biosynthesis were heterologously expressed to increase the amount of fermentable sugars in sugarcane. Transgenic lines heterologously expressing CsCesA, encoding a cellulose synthase from the marine invertebrate Ciona savignyi showed significant increases in their total cellulose synthase enzyme activity as well as the total cellulose content in internodal tissues. Elevation in cellulose contents was accompanied by a rise in hemicellulosic glucose content and uronic acid amounts, while total lignin was reduced in internodal tissues. Enzymatic saccharification of untreated lignocellulosic biomass of transgenic sugarcane lines had improved glucose release when exposed to cellulose hydrolyzing enzymes. Calli derived from transgenic sugarcane lines ectopically expressing galactomannan biosynthetic sequences ManS and GMGT from the cluster bean (Cyamopsis tetragonoloba) were observed to be capable of producing a galactomannan polysaccharide. However, after regeneration, transgenic sugarcane plants derived from those calli were unable to produce the polymer although the inserted genes were transcribed at the mRNA level. While the ectopic expression of Deinococcus radiodurans amylosucrase protein in the cytosol had a detrimental effect on the growth of transgenic lines (plants showed stunted growth through the 18 months growth period in greenhouse), contrastingly targeting the amylosucrase protein into the vacuole resulted in 3 months old transgenic lines which were having high maltooligosaccharide and soluble sugar (sucrose, glucose and fructose) levels in leaves. After 18 months growing in the greenhouse, the mature transgenic lines were morphologically similar to the untransformed lines and also contained comparable maltooligosaccharide and soluble sugar and starch amounts. The non-biosynthesis of galactomannan and amylose polysaccharides in the matured transgenic plants may be due to post-transcriptional protein processing and or protein instability, possibly explainable by other epigenetic mechanisms taking place to regulate gene expression in the at least allo-octaploid species of sugarcane under investigation in this study.