The greatest weather enemy in all fruit destruction is the late spring frost which moves across the country under the high pressure areas that are occasionally seen on the weather maps, and kills the fruit buds.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fulfillment of the requirements for the degree Master of Science Johannesburg, 2018 / Seed recalcitrance in avocado (Persea americana) has meant that avocado genetic material cannot be conserved in orthodox seed banks. Thus, biotechnological approaches have been considered for the long-term conservation of this species’ genetic material, through the cryopreservation of tissue culture-generated axillary buds. A study was conducted to develop a system for the proliferation of in vitro avocado cv. ‘Edranol’ axillary buds for the purpose of cryopreservation. Experiments were conducted to optimise avocado mother plant establishment and pretreatment. It was determined that potting soil mixes comprising of either 1:1:1 pine bark, perlite, river sand or 1:1:1 peat, perlite, river sand were suitable to culture healthy avocado mother plant seedlings. With these soil mixes approximately 2 shoots per plant developed after 11 weeks of transplanting and between 2.9 ± 0.31 and 3.37 ± 0.32 secondary shoots were produced after 5 months. Additionally, the mother plants produced well extended shoots (7.30 ± 1.29 cm; 8.77 ± 1.39 cm) with a sufficient number of axillary buds (7.75 ± 0.39; 6.33 ± 0.53), which were subsequently used as nodal explants. After surface decontamination, the establishment of an aseptic culture in vitro was successfully achieved. Six semi-solid tissue culture media were tested for the proliferation of in vitro axillary buds. Four media comprised of half (½) and full strength Murashige and Skoog (MS) medium (Murashige and Skoog, 1962), with either 0.5 or 1mg/l 6-Benzylaminopurine (BAP). Two media were based on the P. indica medium as proposed by Nel et al. (1983), and comprised of half strength MS macronutrients, full strength MS micronutrients, 2mg/l BAP and 1mg/l GA3. All media were supplemented with 3g/l Gelrite and 30g/l sucrose at pH 5.6-5.8. Physiological measurements were taken six weeks after establishment, the first, the second and the third subculture. Tissue browning, death and contamination were observed in explants cultured on the media containing 0.5mg/l BAP, suggesting that this concentration of BAP was not suitable for cv. ‘Edranol’. Additionally, hyperhydricity appeared to be associated with the media containing ½ MS, which could be attributed to mineral deficiencies. Overall, there was no significant difference in the number of shoots and axillary buds developed across all the media tested, suggesting that endogenous auxin levels were higher than the concentration of cytokinin used in the media tested. In support of this, strong apical dominance and callus formation was observed. An increase in tissue browning, death and hyperhydricity on all the media tested, coupled with a decrease in shoot length, suggested a decline in the vigour of explants in vitro. 1MS + 1mg/l BAP was selected as the most appropriate medium for the initiation of cv. ‘Edranol’ cultures, producing between 3.2 ± 0.2 and 4.9 ± 0.5 axillary buds per explant. However, hyperhydricity, browning and death were observed in explants cultured on this medium. Overall, the in vitro axillary bud explants did not behave predictably or uniformly. Thus, the system was not optimised, indicating that further study is needed for the mass multiplication of axillary buds to be used for the cryo-conservation of avocado genetic material. It is recommended that future experiments will be needed to further test tissue culture media, with a focus on the optimisation of the nutrient and plant growth regulator concentrations. Additionally, the recalcitrance of explants to the in vitro environment may have been influenced by the physiological state of the mother plants, indicating that research should be focused on the effect which the mother plants may have on the endogenous responses of the in vitro explants. / MT 2018

Thesis (M.Sc. (Agriculture)) --University of Limpopo, 2008 / The mineral nutrition of indigenous crop species is not well documented like other known crop species, thus making it difficult for one to know how to plant and maintain the crops. Mmupudu (Mimusops zeyheri), which, happens to be a wild crop, is one of the indigenous trees of interest to the Discipline of Plant Production, University of Limpopo. The current study gives baseline information that will be important in various environmental physiology studies of this plant. Physiological studies will be necessary to assess the importance of “limiting” mineral nutrients in the accumulation of certain mineral nutrients in Mmupudu in relation to its productivity. The experiment was arranged as a 2 x 3 factorial in RCBD, with the first and second factors being time of sampling and location, respectively. The three locations where data were collected were Chuenespoort, Bochum and Sekgosese. In each location, the experiment was replicated 10 times. Data were analyzed using ANOVA and means were separated using the least significant difference test. The two-factor interaction was nonsignificant (P ≥ 0.10) for both pH and electrical conductivity. Soil pH was not affected by time in all three locations suggesting that abscised flowers and fruitlets have no effect on pH. Leaf K experienced an increase of 65% at Chuenespoort and a decrease of soil K after fruiting by 44%. Leaf and soil P decreased after fruiting in all locations as was the case with Cu. Chuenespoort and Sekgosese experienced a decrease in leaf Mn after fruiting while soil Mn decreased in all locations after fruiting. Sekgosese experienced an increase of 25% soil Mg after fruiting, whereas leaf Mg decreased in all locations. / National Research Foundation and the Department of Water Affairs and Forestry

Thesis (M.Sc. Agric. (Horticulture)) --University of Limpopo, 2008 / The mineral nutrition of indigenous crop species is not well documented like other known crop species, thus making it difficult for one to know how to plant and maintain the crops. Mmupudu (Mimusops zeyheri), which, happens to be a wild crop, is one of the indigenous trees of interest to the Discipline of Plant Production, University of Limpopo. The current study gives baseline information that will be important in various environmental physiology studies of this plant. Physiological studies will be necessary to assess the importance of “limiting” mineral nutrients in the accumulation of certain mineral nutrients in Mmupudu in relation to its productivity. The experiment was arranged as a 2 x 3 factorial in RCBD, with the first and second factors being time of sampling and location, respectively. The three locations where data were collected were Chuenespoort, Bochum and Sekgosese. In each location, the experiment was replicated 10 times. Data were analyzed using ANOVA and means were separated using the least significant difference test. The two-factor interaction was nonsignificant (P ≥ 0.10) for both pH and electrical conductivity. Soil pH was not affected by time in all three locations suggesting that abscised flowers and fruitlets have no effect on pH. Leaf K experienced an increase of 65% at Chuenespoort and a decrease of soil K after fruiting by 44%. Leaf and soil P decreased after fruiting in all locations as was the case with Cu. Chuenespoort and Sekgosese experienced a decrease in leaf Mn after fruiting while soil Mn decreased in all whereas leaf Mg decreased in all locations. / the National Research Foundation and the Department of Water Affairs and Forestry

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Made available in DSpace on 2014-06-11T19:23:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-06-09Bitstream added on 2014-06-13T19:50:03Z : No. of bitstreams: 1 leal_rm_me_jabo.pdf: 294028 bytes, checksum: fc3f992466714eeeceb495e8ba187cbd (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A presente pesquisa teve o objetivo de estudar os efeitos da adubação nitrogenada sobre caramboleiras (cv. B-10) em implantação, através de análises químicas do solo, da determinação do crescimento, da amostragem de folhas e inflorescências, da avaliação do estado nutricional, em relação ao nitrogênio, através do uso do clorofilômetro, além do início da produção de frutos. Para tanto, foi instalado um experimento na Fazenda Manga Rosa, no município de Bonfim Paulista - SP, Brasil, sobre um Latossolo Vermelho eutroférrico, que foi conduzido de janeiro/2003 a fevereiro/2006. O delineamento experimental adotado foi em blocos ao acaso, com cinco tratamentos que corresponderam a doses de nitrogênio (uréia) e quatro repetições. Na implantação as doses utilizadas foram iguais a zero, 30,60, 90 e 120 g de N planta-1 e, nos 1°, 2° e 3° anos de experimentação utilizou-se o dobro, o triplo e o quádruplo das doses iniciais. A aplicação do fertilizante nitrogenado, a partir do segundo ano de experimentação, promoveu diminuição significativa do pH que aumentou a acidez potencial e diminuiu as concentrações de potássio, cálcio e magnésio, bem como a soma de bases e a saturação por bases. As caramboleiras do tratamento testemunha não floresceram e apresentaram menor teor foliar de N, em relação àquelas que receberam o adubo. O estado nutricional das plantas, em relação ao nitrogênio pode ser avaliado com o uso do clorofilômetro, pois, houve correlação positiva entre a leitura SPAD e o teor foliar de N determinado pela análise química, e uma dose próxima de 120 g de N planta-1 proporcionou os melhores resultados para a caramboleira na fase de implantação. / The present work was conducted to study the effect of nitrogen fertilization on star fruit (cv. B-10) at establishment, through soil nitrogen chemical analyses, plant growth, leaf and inflorescence sampling, nitrogen nutrition evaluation with a chlorophylometer, as well as the beginning of fruit production. The experiment was set at Manga Rosa Farm, in Bontim Paulista, SP, Brazil, under Eutrustox soil from January 2003 to February 2006. The experiment design was randomized blocks, with tive treatments corresponding to nitrogen (urea) rates, with four replications. At the plant establishment, N rates utilized were zero, 30, 60, 90 and 120 9 of N planr1 and, at the 1st, 2nd and 3rd years of experimentation, two fold, three fold and four fold of initial rate. The nitrogen fertilizer application, afier the second year of experiment, resulted in significant pH reduction which increased potential acidity and decreased potassium, calcium and magnesium concentrations, as well as the sum of bases and base saturation. Control star fruit did not flower and showed lower foliar N concentration in relation to those which received fertilizer. The plant nitrogen nutritional state can be evaluated with a chlorophylometer, because a positive correlation was observed between SPAD and N in leaves determinated by chemical analisys, and a rate near of 120 9 of N planr1 showed the best results for star fruit at orchard establishment.

Made available in DSpace on 2014-06-11T19:29:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-10-24Bitstream added on 2014-06-13T19:39:05Z : No. of bitstreams: 1 souza_ja_me_ilha.pdf: 3840702 bytes, checksum: d1b78493b8f0c387c60f40d0693771e5 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Recentemente foi demonstrado que o boro exibe rápida e significante mobilidade no floema de algumas espécies produtoras de polióis. Os polióis como os açúcares alcoóis sorbitol, dulcitol e manitol possuem a capacidade de complexar o B conferindo a esse elemento alguma mobilidade dentro da planta. As espécies selecionadas foram o cajueiro (não produtora de sorbitol) e o pessegueiro (produtora de sorbitol). O trabalho teve por objetivo verificar a mobilidade de B aplicado via foliar em mudas de cajueiro e pessegueiro. As espécies foram conduzidas separadamente em dois experimentos em casa de vegetação pertencente a UNESP/FEIS no município de Ilha Solteira-SP. O delineamento experimental foi em blocos ao acaso, com três repetições, em parcelas subdivididas, em duas épocas (30 e 60 dias). Foram avaliados nas parcelas cinco tratamentos e nas subparcelas dois tipos de folha (folhas velhas e folhas novas). Os tratamentos estudados constituiram-se da adubação via solo e/ou via foliar com boro marcado ou não com 10B, da seguinte forma: sem adubação via solo e foliar com B (Sol -B Fol -B); sem adubação via solo com B e adubação foliar com 10B (Sol -B Fol 10 B); adubação via solo com B e sem adubação foliar (Sol B Fol -B); adubação via solo com B e foliar com 10B (Sol B Fol10B) e adubação via solo com 10B e foliar com B (Sol10B Fol B). Na adubação via solo o mesmo foi acrescido de B na dose de 0,5 mg kg-1 de solo e na adubação via foliar aplicação de solução com B na doses de 255 mg L-1, utilizando-se como fonte de B o ácido bórico e ácido bórico enriquecido com átomos de 10 B (99%). Foram avaliados quinzenalmente a altura e o número de folhas e o teor total de B e a porcentagem de B na folha velha e folha nova proveniente do fertilizante aos 30 e 60 dias após a aplicação dos tratamentos / Recently it was demonstrated the boron mobility in the phloem of some species producing polyols. The polyols or such alcohols sugar as sorbitol, mannitol and dulcitol are capable of complexing B giving to this element some mobility within the plant. This work had the objective to study the effect of fertilization with boron in the soil and leaves of cashew and peach seedling. They were conducted two experiments for 120 days in the greenhouse at UNESP, Ilha Solteira/SP. The experimental design was randomized blocks with three replications in a split plot, in two times for collection of leaves (30 and 60 days after application of treatments). We studied five treatments in plots and two ages of leaves in the subplots (old leaves and new leaves). The treatments studied were: no fertilizer with B in the soil and leaves (Sol -B Fol -B); without fertilizer with B in the soil and leaves with 10B (Sol - B Fol10B); fertilizing in the soil with B and leaves without B (Sol B Fol -B); fertilizing in the soil with B and leaves with 10B (Sol B fol10B) and fertilizing in the soil with 10 B and leaves with B (Sol10B Fol B). Were evaluated the height and the number of leaves biweekly and B total content and B percentage at the leaf from the fertilizer (% Bfopf) at 30 and 60 days. There was no fertilization effect with boron in the cashew seedling growing . The foliar fertilization with boron showed higher increase in the leaves number on peach seedlings at 60 days after fertilization. Boron foliar application is restricted or intermediate mobility in mobile cashew and peach evaluated at 30 and 60 days after fertilization

Resumo: A presente pesquisa teve o objetivo de estudar os efeitos da adubação nitrogenada sobre caramboleiras (cv. B-10) em implantação, através de análises químicas do solo, da determinação do crescimento, da amostragem de folhas e inflorescências, da avaliação do estado nutricional, em relação ao nitrogênio, através do uso do clorofilômetro, além do início da produção de frutos. Para tanto, foi instalado um experimento na Fazenda Manga Rosa, no município de Bonfim Paulista - SP, Brasil, sobre um Latossolo Vermelho eutroférrico, que foi conduzido de janeiro/2003 a fevereiro/2006. O delineamento experimental adotado foi em blocos ao acaso, com cinco tratamentos que corresponderam a doses de nitrogênio (uréia) e quatro repetições. Na implantação as doses utilizadas foram iguais a zero, 30,60, 90 e 120 g de N planta-1 e, nos 1°, 2° e 3° anos de experimentação utilizou-se o dobro, o triplo e o quádruplo das doses iniciais. A aplicação do fertilizante nitrogenado, a partir do segundo ano de experimentação, promoveu diminuição significativa do pH que aumentou a acidez potencial e diminuiu as concentrações de potássio, cálcio e magnésio, bem como a soma de bases e a saturação por bases. As caramboleiras do tratamento testemunha não floresceram e apresentaram menor teor foliar de N, em relação àquelas que receberam o adubo. O estado nutricional das plantas, em relação ao nitrogênio pode ser avaliado com o uso do clorofilômetro, pois, houve correlação positiva entre a leitura SPAD e o teor foliar de N determinado pela análise química, e uma dose próxima de 120 g de N planta-1 proporcionou os melhores resultados para a caramboleira na fase de implantação. / Abstract: The present work was conducted to study the effect of nitrogen fertilization on star fruit (cv. B-10) at establishment, through soil nitrogen chemical analyses, plant growth, leaf and inflorescence sampling, nitrogen nutrition evaluation with a chlorophylometer, as well as the beginning of fruit production. The experiment was set at Manga Rosa Farm, in Bontim Paulista, SP, Brazil, under Eutrustox soil from January 2003 to February 2006. The experiment design was randomized blocks, with tive treatments corresponding to nitrogen (urea) rates, with four replications. At the plant establishment, N rates utilized were zero, 30, 60, 90 and 120 9 of N planr1 and, at the 1st, 2nd and 3rd years of experimentation, two fold, three fold and four fold of initial rate. The nitrogen fertilizer application, afier the second year of experiment, resulted in significant pH reduction which increased potential acidity and decreased potassium, calcium and magnesium concentrations, as well as the sum of bases and base saturation. Control star fruit did not flower and showed lower foliar N concentration in relation to those which received fertilizer. The plant nitrogen nutritional state can be evaluated with a chlorophylometer, because a positive correlation was observed between SPAD and N in leaves determinated by chemical analisys, and a rate near of 120 9 of N planr1 showed the best results for star fruit at orchard establishment. / Orientador: William Natale / Coorientador: Renato de Mello Prado / Banca: Takashi Muraoka / Banca: Ben-Hur Mattiuz / Mestre

Thesis (MSc (Horticulture))--University of Stellenbosch, 2006. / A growing number of fruit producers in warm areas are adopting the use of overtree evaporative cooling (EC) as a technique to reduce sunburn and enhance colour development of red or blushed fruit. Because fruit do not have efficient mechanisms of utilising and/or dissipating solar radiation, fruit surface temperature may rise 10 – 15oC higher than the ambient air temperature, making them very susceptible to sunburn. Sunburn negatively affects the appearance of the fruit, and they cannot be sold for fresh market consumption, which receives the highest prices. Evaporative cooling uses a sprinkler system to cool the trees from above. Energy needed to evaporate the water is extracted from the fruit skin, cooling the fruit down. The air around the trees is cooled, and a more favorable microclimate is created in the orchard. Producers have also found that the use of EC just prior to sundown and sometimes around sunrise has improved colour development on red apples (especially early varieties) before harvest. In this study, two apple (‘Cripps’ Pink’ and ‘Royal Gala’) and two pear (‘Rosemarie’ and ‘Forelle’) cultivars under EC were compared with control fruit in terms of maturity, colour, sunburn and concentrations of polyphenolics in the skin. Two EC treatments were given; early application starting from the second week in December, and late application starting two to four weeks before harvest. Photosynthetic responses were measured, as well as fruit and leaf temperatures. Underlying physiological responses of trees and fruit to EC were investigated, particularly the phenomenon of acclimation and the potential for colour development and heat stress. Fruit surface temperature of fruit under EC was found to be significantly lower than control fruit. In both apple cultivars a significant increase in fruit skin anthocyanin concentration and a decrease in phenolic content was found as the season progressed. In both pear cultivars there was a significant decrease in both anthocyanin and phenolic. No significant differences were found in anthocyanin content between treatments in either the apple or pear cultivars. In both apple cultivars a higher phenolic content was found in the peel of the EC treatments. A decrease of up to four percent in leaf and fruit surface temperature was found under EC. No significant difference in trunk circumference was found in any of the cultivars. The late EC treatment in ‘Cripps’ Pink’ had a significantly faster rate of budbreak than the control and early EC treatments. Significantly higher transpiration was observed in leaves under EC. ‘Royal Gala’ fruit under EC had less sunburn than control fruit. Unfortunately the system broke down on a hot day, causing more sunburn on ‘Cripps’ Pink’ fruit under EC. Heat tolerance of apple fruit grown under EC was evaluated in ‘Cripps’ Pink’ and ‘Royal Gala’ by determining the maximum quantum yield of chlorophyll fluorescence (Fv/Fm). Measurements were also made 12 hours after the heat treatments to determine recovery. ‘Cripps’ Pink’ fruit from both EC treatments, but particularly the early EC treatment, were less resistant to heat stress than control (non-EC) fruit at the “threshold” air temperature of 45°C. Apples were able to recover from heat treatments in the range of 32-38oC fruit surface temperature, and generally also recovered fully after 43-45°C fruit surface temperature when exposure did not exceed four hours. This knowledge could be helpful in the management of sunburn, for example when determining the threshold temperature for the activation of evaporative cooling treatments. Knowledge about the various effects evaporative cooling and the subsequent lowering of ambient temperatures has on fruit trees and fruit could contribute greatly to producers’ ability to grow high quality fruit. EC can be used successfully for controlling sunburn and increasing fruit colour, but the system needs to be controlled very carefully and care should be taken that it does not fail on a hot day, as it did during this study.

Thesis (PhD(Agric) (Horticulture))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Branch architecture is the position and length of lateral shoots along a main axis, and is dependant on competitions (dominance) among meristems and lateral shoots. In areas with inadequate winter chilling, branch architecture is altered, the dynamics of which are poorly understood. The aim of this work was to better understand the dynamics underlying plant architecture. In the first part of the study, the dynamics of apple branch architecture were characterized for two cultivars, Golden Delicious and Granny Smith, in areas with differing degrees of inadequate winter chilling (a warm area and a cool area). In an additional study, progeny of a mapped ‘Telamon’ (columnar habit) and ‘Braeburn’ (normal habit) population were used to quantify branch architecture in an effort to develop quantitative trait loci (QTLs) for branching habit. Although branch architecture could be quantified, it was difficult to relate these to known qualitative branching habits, as the columnar gene is dominant and limited the number of progeny that were not columnar. With the exception of organogenesis in the season preceding growth, acrotonic tendencies (number of growing laterals, lateral length, fruit set) were not related to temporal (primigenic) dominance of the distally located buds or flowers within an axis. In the warm area, both relative time of budburst and flowering among buds within an axis did depict a loss of acrotony (positional dominance of the distally located buds and shoots within an axis). The first buds to burst and flower in the warm area had the greatest ability to grow out and set fruit, respectively, regardless of position within the shoot, implicating a role for primigenic dominance when chill unit accumulation was inadequate. Overall, temporal (primigenic) dominance in the warm area, and positional dominance (acrotony) in the cool area dictated lateral outgrowth and development. / AFRIKAANSE OPSOMMING: Takargitektuur verwys na die posisie en lengte van laterale lote soos dit oor die hoofas versprei voorkom. Dit is afhanklik van kompetisie (dominansie) tussen meristeme en laterale lote. In areas met onvoldoende winterkoue word takargitektuur verander, maar die dinamika van hierdie veranderinge word nog nie goed verstaan nie. Die doel van hierdie navorsing was om die onderliggende dinamika wat plantargitektuur beïnvloed beter te verstaan. In die eerste deel van die studie is die dinamika van appeltakargitektuur van twee cultivars Golden Delicious en Granny Smith, in twee areas met verskillende mate van onvoldoende winterkoue bestudeer (’n warm en ’n koel area). In ’n verdere studie is die nageslag van ‘n ‘Telemon’ (kolomgroeiwyse) en ‘Braeburn’ (normale groeiwyse) kruising gebruik om takargitektuur te kwantifiseer. Dit is gedoen in ’n poging om kwantitatiewe eienskapslokusse vir vertakking te ontwikkel. Alhoewel takargitektuur kwantifiseer kon word, was dit moeilik om dit in verhouding te bring met kwalitatiewe vertakkingspatrone daar die kolomgroeiwyse-geen dominant is en die aantal indiwidue in die nageslag wat nie ’n kolomgroeiwyse gehad het nie beperk was. Met die uitsondering van organogenese in die seisoen wat groei voorafgaan, is akrotoniese neigings (aantal laterale lote, laterale lootlengte, vrugset) nie beïnvloed deur tydelike (primigeniese) dominansie van distale knoppe of blomme binne ’n as nie. In die warm area het beide relatief tot knopbreek en blomtyd binne ’n assestelsel die verlies aan akrotonie beskryf (posisionele dominansie van distale knoppe en lote in assestelsel). Die eerste knoppe wat bot en blom in die warm area het die beste vermoë om te groei en vrugte te set, onafhanklik van hul posisie. Dit impliseer die rol van primigeniese dominansie wanneer ’n gebrek aan winterkoue ervaar word. Algemeen gesien was dit tydelike (primigeniese) dominansie in warm areas en posisionele dominansie (akrotonie) in die koeler area wat lateraal bot en ontwikkeling bepaal het.