Doctorat en philosophie et lettres / info:eu-repo/semantics/nonPublished

Afin de freiner les multiples conséquences engendrées par l’urbanisation, notamment la présence d’îlots de chaleur, l’augmentation d’espaces verts est une des stratégies mise de l’avant par de plus en plus de municipalités. À Montréal, plusieurs arrondissements ont récemment agrandi leurs fosses de plantation sur trottoir pour, entre autres, favoriser la survie des arbres et augmenter le nombre d’arbres plantés. Dans ces grandes fosses, la plantation d’une végétation herbacée compagne est un nouvel objectif afin de promouvoir la biodiversité et les services écologiques. Cependant, peu d’informations existent à ce jour sur les espèces qui peuvent être plantées durablement dans ce type d’environnement hostile. Dans ce contexte, mon projet avait pour objectif d’identifier un ou des mélanges d’ensemencement efficaces et performants pour favoriser la biodiversité et contrer l’invasion d’espèces nuisibles, tout en maximisant les services écologiques telle la fertilité des sols et la pollinisation. J’ai testé quatre mélanges, dont trois de type soleil et un de type mi-ombre, composés de 19 à 33 espèces. Mes résultats indiquent que les mélanges les plus diversifiés réduisent significativement l’établissement d’espèces nuisibles en plus d’accroitre l’abondance et la diversité de pollinisateurs. Cependant, la diversité végétale et la fertilité du sol dans les fosses étaient similaires entre les mélanges après deux années. Cette étude met en lumière les fosses de trottoir végétalisées en milieu urbain comme une approche novatrice pour l’avenir du verdissement et de l'aménagement urbain, tout en apportant des perspectives précieuses pour améliorer les futures initiatives dans ce domaine. / To curb the multiple consequences of urbanization, notably the presence of heat islands, increasing the amount of green space is one of the strategies put forward by an increasing number of municipalities. In Montreal, several boroughs have recently enlarged their sidewalk planting pits to, among other things, favor tree survival and increase the urban canopy. In these large pits, planting herbaceous companion vegetation is a new objective to promote biodiversity. However, more information is needed on which species can be sustainably planted in this hostile environment. In this context, my project aimed to identify the most effective and efficient seed mix regarding biodiversity, weed control, and ecological services (soil fertility and pollination). We tested four seed mixes, three sunny and one semi-shady, composed of 19 to 33 species. Our results indicate that the most diverse mix significantly reduces weed establishment and increases pollinator abundance and diversity. However, soil fertility and plant diversity in the pits were similar between seed mixes after two years. This study highlights urban vegetated sidewalk pits as an innovative approach to the future of greening and urban design, while providing valuable insights to improve future initiatives in this field.

Master of Science / Department of Horticulture, Forestry, and Recreation Resources / Cheryl Boyer / The nursery industry in the United States, particularly in the Great Plains region is growing; however, materials used in creation of artificial substrates used to grow ornamental nursery crops continue to increase in price. Eastern Redcedar (Juniperus virginiana L.) is an indigenous plant throughout much of the United States and, in the Great Plains, it has become a pest. Use of wood-based substrates (primarily composed of pine trees) has been proven effective in both nursery and greenhouse production. Eastern Redcedar chips (JVC) could become a local and sustainable resource for the horticulture industry throughout the Midwest. Experiments were conducted to determine if JVC could be used as a substrate to replace or supplement three major substrate components; pine bark (PB), perlite, or peat moss. Four studies evaluated ornamental crop growth: two focused on comparing nursery crop production in PB and JVC, one focused on greenhouse production in peat moss, and the last on plant propagation in perlite. The first experiment (Chapter 2) involved combining ratios of JVC and PB with two fertilizer rates to grow woody plants. It was shown that while higher levels of fertilizer produced larger plants, that plants grown at either rate of fertilizer showed the same growth trends. As JVC content increased more than 20%, growth measurements such as shoot dry weight and plant height decreased. This decrease in growth can be attributed to the physical properties of JVC, which showed that as JVC content increased so did airspace with a corresponding decrease in container capacity. A follow-up experiment (Chapter 4) evaluated several different particle sizes of JVC and a PB control. It showed that despite the different particle sizes JVC substrate produced less growth than plants grown in PB though plants grown in JVC were all similar to each other. Another experiment (Chapter 3) was conducted to evaluate if JVC as a replacement for peat moss in producing greenhouse-grown annual crops. JVC’s low container capacity hindered plant growth with each increase in JVC content associated with a decrease in growth. Finally a propagation experiment (Chapter 5) used a combination of finely-ground JVC and perlite to grow cuttings of woody and herbaceous plants. It was shown that, in most cases, JVC and perlite were equivocal rooting cuttings. This work demonstrates that JVC can be used as a PB and peat moss supplement, but not a replacement nursery and greenhouse crop production. Use of JVC as a perlite replacement for plant propagation is recommended.

Doctor of Philosophy / Department of Horticulture, Forestry, and Recreation Resources / Dale J. Bremer / Jack D. Fry / Researchers and practitioners can use numerous techniques to measure or estimate evapotranspiration (ET) from turfgrass but little is known about how they compare to ET using standard lysimeters. An investigation was conducted to compare measurements of ET from lysimeters (LYS[subscript]E[subscript]T) with ET estimates from the FAO56 Penman-Monteith (PM[subscript]E[subscript]T) and Priestley-Taylor (PT[subscript]E[subscript]T) empirical models, atmometers (AT[subscript]E[subscript]T), eddy covariance (EC[subscript]E[subscript]T), and a canopy stomatal conductance model that estimates transpiration (COND[subscript]T). Methods were compared at the same site during the 2010, 2011, and 2012 growing seasons. Overall, PT[subscript]E[subscript]T and EC[subscript]E[subscript]T were not different from LYS[subscript]E[subscript]T, whereas PM[subscript]E[subscript]T, AT[subscript]E[subscript]T, and COND[subscript]T, increasingly underestimated LYS[subscript]E[subscript]T. Differences exist among ET measurement techniques and one should employ the technique that best fits their situation. An atmometer is an inexpensive tool that can be used to measure turfgrass ET within microclimates, such as those typically found in an urban home lawn. An investigation was conducted to compare AT[subscript]E[subscript]T estimates with PM[subscript]E[subscript]T estimates within a number of lawn microclimates. Home lawns in Manhattan and Wichita, KS, were selected for study during the growing seasons of 2010 and 2011. Open sward AT[subscript]E[subscript]T was 4.73 mm d[superscript]-[superscript]1, whereas PM[subscript]E[subscript]T was 5.48 mm d[superscript]-[superscript]1. Within microclimates, AT[subscript]E[subscript]T was 3.94 mm d[superscript]-[superscript]1 and PM[subscript]E[subscript]T 3.23 mm d[superscript]-[superscript]1. Atmometers can provide practitioners with reliable estimates of PM[subscript]E[subscript]T within microclimates. Zoysiagrass (Zoysia spp.) is a common turfgrass used on home lawns and golf courses. However, poor shade tolerance and cold hardiness have limited its use in the transition zone. A study was conducted to determine changes and differences in growth and physiology among selected Zoysia over a three-year period (2010-2012) in the transition zone. The genotypes were 'Emerald' [Z. japonica × Z. pacifica], 'Zorro' [Z. matrella], 'Meyer' and Chinese Common [Z. japonica], and experimental progeny Exp1 [Z. matrella × Z. japonica], and Exp2 and Exp3 [(Z. japonica × Z. pacifica) × Z. japonica]. 'Zorro' and 'Emerald' experienced winter injury. 'Meyer', Chinese Common, and Exp1 showed poor performance over the three-years. The Exp2 and Exp3 progeny, maintained high percent cover, visual quality, and tiller density, and may provide practitioners more shade-tolerant cultivar choices in the transition zone.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Fertility-building crops (FBCs) offer the opportunity to alleviate the costs of inorganic fertiliser by providing an alternative supply of available nitrogen (N) in soils. A survey of relevant literature reviewed the types of FBCs, their nitrogen accumulation potentials, residue characteristics, and subsequent release patterns. It also identified a paucity of data concerning the response of different species to UK climatic, soil, and management conditions. In order to investigate these relationships further pot and field trials were established in 2007 at the Royal Agricultural College, Cirencester (SP 00481 01382) and at Coates Manor Farm (SO 98473 00402) on Sherborne series (typical Cotswold) soils, to investigate the biology and morphology of FBCs potentially suitable for short term fertility-building, their accumulation of N under field conditions, and its subsequent recovery within test crops. Data so obtained was used as a verification and refinement tool for the FBC model (Cuttle et al, 2003), a simple, commercially applicable, rotation-based model which can be applied to both organic and conventional production systems. Nine leguminous and two non-leguminous FBC treatments were established in April 2007 by straight sowing, followed by mulching at the conclusion of the nitrogen accumulation phase and by undersowing in spring barley (Hordeum sativum). The recovery test crops (winter and spring wheat Triticum aestivum L.) were established in September 2007 and March 2008. All FBCs established successfully. Above-ground dry matter (DM) yield and residue quality (C:N ratio) of FBCs varied significantly (P<0.05) between crops and cropping regimes with a significant correlation (r2=0.418) between DM yields and C:N ratios. FBCs and cropping regimes had significant effects (P<0.001 and P<0.05 respectively) on potential mineralisable nitrogen (PMN) levels in the soil and on the grain yields of winter and spring wheat test crops. Straight sown Lupinus albus, Trifolium pratense, Trifolium repens and a legume mixture resulted in higher winter wheat grain yields. However, the opportunity cost associated with straight sowing (i.e. the gross margin foregone from a spring barley crop) meant that the rotation would probably not be viable economically. Undersown Medicago lupulina, Vicia villosa, T. pratense, T. repens and the legume mixture gave worthwhile yield increases in spring wheat without incurring a yield penalty in the spring barley cover crop. Following enhancement and using actual data from the trials, the FBC model (Cuttle et al, 2003) provided encouraging predictions (R>0.6) for soil mineral nitrogen (SMN) and key parameters were identified for future use. It was concluded that FBCs established for short term soil fertility building could provide a worthwhile enhancement of soil N levels and grain yields in a conventional arable rotation, particularly in spring wheat following FBCs undersown in spring barley. It was also concluded that the FBC model (Cuttle et al, 2003), following further enhancement, and using additional data from these and other similar trials, could provide reasonably accurate estimates of SMN to aid more precise applications of N fertiliser in the future.

Thesis (MBA)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Pierre du Plooy co-founded Prophyta (Pty) Ltd, a company that provided technical consultation services in the fields of horticulture and soil science to the South African deciduous fruit industry. Initially, the founders employed goods-dominant logic, viewing their services as intangible products that needed to be sold to clients. Between the founding of Prophyta in September 2012 and November 2014, Pierre du Plooy’s value proposition, service offering and revenue model diverged from those of other consultants in Prophyta, to the extent that he resigned from Prophyta and became an independent horticultural consultant. The study focussed on Pierre du Plooy’s existing clients. The clients were surveyed to determine their satisfaction with the current service offering, their interest in additional services, their openness toward alternative revenue models and key success factors according to them. A questionnaire was designed and 29 clients were invited to participate in the survey. Six responded, resulting in a response rate of 21 percent. Client satisfaction with the current service was measured using SERVQUAL. Fifteen statements applicable to the horticulture advisory service were made and respondents’ expectations and perceptions measured on a five point Likert scale. The values obtained for the expectation and corresponding perception per statement were used to calculate a difference score. A negative value for the difference score meant the perception of the current service exceeds client expectations regarding the statement in question. In general, the clients were satisfied with the current service offering. Two main aspects needed focus. A horticulturist needs to stay up-to-date with new research and technologies, requiring him to stay abreast of relevant literature, as well as attending symposia and production areas abroad. A horticulturist also has to be very attentive to keep classified information shared by clients confidential. The first aspect relates to the creation of new knowledge, the second to strengthening and building of relationships based on trust. According to the literature, both these aspects form the bases of competition and are very important in obtaining and maintaining a competitive advantage. It is recommended that Pierre du Plooy focus on above-mentioned aspects in order to maintain a sustainable competitive advantage over competitors. It is also recommended to repeat the client survey every two years in order to monitor changing client expectations and make sure client needs are being met.

Thesis (PhD)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The curricula of the Technikon National Diplomas in Horticulture, Landscape Technology and Parks (Open Space) and Recreation Management have been intermittently revised since the original inception in 1972 of the NO in Horticulture. The shortcomings in the process of curriculum revision, with special reference to programmes in Horticulture, were identified. The institution of outcomes-based education (aBE) and the National Qualifications Framework (NQF) followed the promulgation of the South African Qualifications Authority Act (No. 58 of 1995). All curricula are currently being written in terms of learning outcomes that qualifying learners will be expected to demonstrate. The primary aim of this research study has been based upon the proposition that a scientifically validated situational analysis is an essential precursor to the design or redesign of a curriculum for tertiary-level horticultural training. A situational analysis that includes the sectors of Amenity horticulture, Arboriculture, Floriculture, Landscape, Nursery production, Nursery retail and Turf was undertaken. The results of this analysis were to be utilised in the development of a theoretical curriculum framework, which may be used in the development of a revised curriculum. The secondary aims of the study are complementary to the primary aim as the situational analysis has led directly to the identification of the core and specific skills/competencies within the seven sectors, the degree to which horticulturists are seen to have prepared themselves for their careers, the attributes or qualities employers expect of a qualified horticulturist and the values applicable to the horticulture profession. This research is regarded as exploratory as little documentation exists regarding the competencies being applied by horticulturists within the different sectors. As it describes the characteristics of horticulture education and training and tries to understand the meaning and relevance of the data gathered, it may also be defined as descriptive. It is also an applied research study as its focus is on the sector-specific curriculum development needs in the horticulture industry. A triangulation approach to the study was followed that utilised a quantitative as well as a qualitative approach. This served to heighten the reliability and the validity of the research. In the qualitative approach, use was made of both personal and focus group interviews, which enabled the researcher to study the problem at greater depth. The mail survey, which used a self-administered questionnaire, facilitated the collection of empirical data that was used to corroborate and extend the generalisability of the qualitative findings to a national level and was the quantitative approach followed. While the situational analysis has led to an extensive amount of empirical data relative to the revision of the curricula, the development of a theoretical curriculum framework is seen as the logical conclusion of this analysis as it represents a synthesis of the most important findings of the study. Its presentation to the industry as a concept curriculum framework, upon which a revised curriculum for technikon horticulture training may be based, is recommended. The development of a framework structured in a format compatible with the NQF, aims at meeting the curriculum needs of the different sectors of the industry. / AFRIKAANSE OPSOMMING: Die kurrikula van die Technikons se Nasionale Diplomas in Tuinbou, Landskaptegnologie en Parke- (Oopruimte) en Rekreasiebestuur is sedert die instelling van die NO in Tuinbou in 1972, by tye verander. Die tekortkominge in die proses van kurrikulumhersiening, met spesiale verwysing na programme in Tuinbou, is uitgewys. Die instelling van uitkomsgebaseerde onderwys en die Nasionale Kwalifikasieraamwerk (NKR) het op die proklamasie van die Suid Afrikaanse Kwalifikasie-Owerheid Wetsontwerp (No. 58 van 1995) gevolg. Alle kurrikula word tans in leeruitkomstes wat kwalifiserende leerders sal moet kan demonstreer, omskryf. Hierdie navorsing berus primêr op die uitgangspunt dat 'n belangrike voorvereiste vir die ontwerp of herontwerp van 'n tersiêre vlak-kurrikulum vir tuinbouopleiding op 'n geldige, wetenskaplike situasie-analise gegrond moet wees. 'n Situasie-analise wat die sektore van Baangras, Blommekweek, Boomteelt, Gemeenskapstuinbou, Kwekerykleinhandel, Kwekeryproduksie en Landskap insluit, is onderneem. Die resultate van hierdie situasie-analise sou vir die ontwikkeling van 'n teoretiese kurrikulumraamwerk tydens kurrikulumhersiening benut kon word. Die sekondêre doel van hierdie studie is aanvullend tot die primêre doel aangesien die resultate van die situasie-analise tot die identifisering van die kern- en spesifieke vaardighede/bevoegdhede binne die sewe sektore sou kon bydra. Die mate waartoe tuinboukundiges hul met sukses vir hul loopbaan voorberei het, die eienskappe wat 'n werkgewer van 'n gekwalifiseerde tuinboukundige sou kon verwag en die waardes wat op die tuinbouprofessie van toepassing is, word ook hierdeur geraak. Hierdie navorsing lsverkennend van aard aangesien daar min literatuur beskikbaar is met betrekking tot die bevoegdhede wat deur tuinboukundiges in die verskillende sektore toegepas word. Aangesien dit die eienskappe van tuinbouopvoeding en - opleiding beskryf en 'n poging is om die betekenis en relevansie van die ingesamelde data te verstaan, kan dit ook as beskrywend beskou word. Omdat die fokus op die spesifieke kurrikulumontwikkelingsbehoeftes van die tuinboubedryf geplaas is, is dit ook 'n toegepaste studie. 'n Triangulasiebenadering tot die studie is gevolg waardeur van beide 'n kwantitatiewe en 'n kwalitatiewe benadering gebruik gemaak is. Die betroubaarheid en die geldigheid van die navorsing is hierdeur verhoog. Die kwalitatiewe benadering het van persoonlike en fokusgroeponderhoude gebruik gemaak, wat aan die navorser die geleentheid gebied het om 'n diepgaande ondersoek te doen. Die kwantitatiewe benadering, waar van 'n posopname met 'n self- ingevulde vraelys gebruik gemaak is, het die insameling van empiriese data moontlik gemaak. Hierdie data kon gebruik word om die kwalitatiewe bevindinge tot by 'n nasionale vlak te verbreed. Die situasie-analise het 'n groot hoeveelheid empiriese data, wat op die hersiening van die huidige kurrikula van toepassing is, opgelewer. Die ontwikkeling van 'n teoretiese kurrikulumraamwerk word as die logiese gevolgtrekking van die analise beskou aangesien dit die sintese van die belangrikste bevindinge verteenwoordig. Die aanbieding hiervan aan die bedryf as 'n konsepkurrikulumraamwerk waarop tuinbouopleiding by technikons gebaseer kan word, word aanbeveel. Hierdie konsepraamwerk is in 'n formaat wat met die NKR verenigbaar is, ontwikkel en is geskoei op die realisering van die kurrikulumbehoeftes van die bedryf en sy afsonderlike sektore.

Highbush blueberry (Vaccinium corymbosum L.) is adapted to soils with high organic matter and acidic pH. Composts provide organic matter and nutrients for growing blueberry in mineral soils, but many composts are high in pH and soluble salts. Acidification with elemental sulfur (S°) can remedy high pH, but the process further increases compost salinity. The objectives of this study were to: i) determine the effects of diverse composts on blueberry growth and nutrient uptake, ii) determine whether S° acidification can ameliorate the negative effects of high compost pH, and iii) develop and validate a simple titration method to determine pH buffering capacity of compost. In our first study, ten composts were evaluated under greenhouse conditions with one-year-old blueberry. Each compost was either acidified or not with S° and then mixed 30% by volume with silt loam soil before planting. Controls were sawdust incorporation or soil only. Plants were managed with a low rate of fertilization to emphasize compost effects on nutrient supply. Compost inorganic nitrogen (N) ranged from 0.1 to 4.1 g∙kg⁻¹, and NO₃-N to NH₄-N ratios were greater than 20:1. Aboveground plant growth and nutrient uptake, including N, phosphorous (P), potassium (K), and boron (B) were higher in soil with compost than in soil with sawdust or soil only. Composts with pH < 7.5 produced more shoot growth than those with higher pH, and composts with EC > 2 dS∙m⁻¹ produced less root growth than those with lower EC. Adding S° reduced compost pH by an average of 1.9 units, and acidification increased shoot and root growth in the composts as well as uptake of many nutrients. Plant growth and N uptake were not correlated with compost N supply. Composts with greater amounts of plant-based feedstocks produced more total shoot growth than manure-based composts. In our second study, 3.7 L blueberry transplants were grown outdoors for 119 d in pots containing compost and soil. Manure feedstocks included separated dairy solids or horse stall cleanings. Plant feedstocks included urban yard trimmings, leaves from street sweeping, conifer bark conditioned with municipal biosolids, or peppermint distillation residue. Control treatments were sawdust amendment or soil only. Plant-based compost treatments had less effect on soil pH and produced 20% greater plant growth than manure-based compost treatments. Plant growth was not different with plant-based composts vs. the sawdust amendment control. Elemental S addition at potting did not acidify soil enough to overcome the increase in pH resulting from compost addition. In our third study, we titrated eight composts with dilute H₂SO₄ to predict response to S° acidification. Our objective was to develop and validate a simple method to determine the pH buffering capacity of compost. Compost pH decreased linearly with laboratory acid addition. Compost pH buffering capacity (linear slope of titration curve) was 0.16 to 0.39 mol H⁺ per kg dry compost per pH unit. To determine correlation between titration and S° acidification, composts samples were incubated with S° at 22° C for 70 d. The majority of the decrease in pH from S° addition occurred within 28 d. Compost pH at 28 d was closely predicted by the laboratory titration. Because of the linearity of compost response to acid addition, a 2-point titration method (one rate of acid addition) is an effective alternative to the 7-point method we used. We conclude that compost pH is the primary limiting factor affecting blueberry response to compost. Compost incorporation provided benefit to blueberry, especially under low N management, and generally increased plant growth and nutrient uptake when compared with plants grown in mineral soil only. Composts made from plant-based feedstocks, rather than manure-based feedstocks, tend to have characteristics which favor blueberry growth, including low buffering capacity, pH, and soluble salts. Feedstocks which showed promise include deciduous leaves, yard debris, bark, and horse bedding with low manure content. Acidification of composts with S° increased plant growth and nutrient uptake, and is a promising technology for eliminating the negative effects of high compost pH. Our method of laboratory titration with dilute acid addition was effective in determining pH buffering capacity of compost, and predicted the compost acidification by S° and the effect of compost on soil pH. / Graduation date: 2012

39 slides / Planting Guidelines; Container Trees and Shrubs (1998) Plant Selection and Selecting your Plants (2000) Selecting, Planting and Caring for Landscape Trees (DVD and VHS (2003); Originally published: 2006 / This slide set with accompanying notes is intended to educate profesisonals in the nursery and landscape trade and lay people interested in proper horticultural practices related to selecting, planting and staking trees.