Resumo: O presente trabalho teve por objetivo avaliar cinco seleções da laranjeira 'Valência', quanto ao potencial industrial com relação às variedades Natal e Valência, enxertadas sobre citrumeleiro 'Swingle' (experimento I) e a tangerineira 'Sunki' (experimento II), avaliando-se o desenvolvimento vegetativo das plantas, porcentagem de pegamento dos frutos, produção e características físico - químicas dos frutos (sólidos solúveis totais - °Brix, acidez, "ratio", porcentagem de suco, índice tecnológico, tamanho dos frutos). Os experimentos foram conduzidos na Estação Experimental de Citricultura de Bebedouro (E.E.C.B.), município de Bebedouro-SP. Os plantios dos experimentos foram realizados em fevereiro de 2001, sob espaçamentos de 7,0 m entre linhas e 5,0 m entre plantas (285 plantas/ha) e 7,0 m entre linhas e 3,0m entre plantas (476 plantas/ha), respectivamente para os experimentos I e II. O delineamento experimental, para ambos experimentos, foi em blocos ao acaso, duas plantas por parcela, quatro repetições e 7 tratamentos, constituídos pelas seguintes variedades copas: 1) Natal, 2) Valência, 3) Valência Don João, 4) Valência Late Burjasot IVIA 35-2, 5) Valência Rohde Red SRA-36, 6) Valência Temprana IVIA-25, 7) Valência Campbell. Para desenvolvimento vegetativo das plantas e características físicas referentes a massa, diâmetro e altura de frutos as seleções 'Valência Late Burjasot' IVIA 35-2 e 'Don João' apresentaram as maiores médias. As mesmas seleções citadas anteriormente apresentaram as melhores médias para porcentagem de pegamento para o experimento I, no experimento II as seleções estudadas não diferiram. Quanto à produção, a seleção 'Valência Late Burjasot' IVIA 35-2 destacou-se na segunda safra. / Abstract: The aim of the current work was to compare the conduct of five 'Valência' sweet oranges selection with in it's industrial potential in relation to the varieties Natal and Valencia on two rootstocks: 'Swingle' (experiment I) and 'Sunki' (experiment II), evaluating the vegetative growth, percentage of fruit set, yield and physical and chemical fruit characteristics. Two experiments were set up in February 2001, at Bebedouro city, São Paulo State, Brazil. The experiments I and II were carried out with the spacements of 7.0 m between rows with 5.0 m between trees and 7.0 m between rows with 3.0 m between trees, respectively. The experimental design used was a randomized blocks, with four replications and two trees per each seven plots. The crown varieties tested were 1) 'Natal', 2) 'Valência', 3) 'Valência Don João', 4) 'Valência Late Burjasot' IVIA 35-2, 5) 'Valência Rohde Red' SRA-36, 6) 'Valência Temprana' IVIA-25, 7) 'Valência Campbell'. For vegetative growth and the physical characteristics referring to mass diameter and height of fruits, the selections 'Valência Late Burjasot' IVIA 35-2 e 'Don João' presented the highest averages The same selections also presented the best averages for percentage of fruit set in experiment I, while in experiment II the selections did not differ. In relationship to production, the selection ' Valência Late Burjasot' IVIA 35-2 stood out in the second crop. Already for revenue in juice and technological index the selections 'Valência Late Burjasot' IVIA 35-2 , 'Don João' and 'Valência Campbell' presented the largest averages comparing the varieties Valência and Natal. / Orientador: Antonio Baldo Geraldo Martins / Coorientador: Eduardo Sanches Stuchi / Banca: José Antonio Alberto da Silva / Banca: Luiz de Souza Corrêa / Mestre

Um dos aspectos que devem ser considerados no mercado de frutas frescas de pessegueiro é a qualidade de seus frutos. Considera-se a aparência como fator importante, sendo a coloração da epiderme relevante, pois se associa com a maturação e o sabor dos frutos. Uma das técnicas de manejo que visam melhorar a qualidade dos frutos é a poda verde, que tem como intuito principal de aumentar a penetração da luz no interior da copa e consequentemente favorecer a pigmentação, bem como, melhorar o sabor dos frutos. Porém, esta técnica pode apresentar resultados variáveis, de acordo com a época e a forma em que a mesma é realizada. O objetivo deste trabalho foi de determinar o período e a forma de execução da poda verde para melhorar a qualidade dos frutos de pessegueiros. O trabalho foi conduzido em pomar comercial no município de Dois Vizinhos (PR), nos ciclos produtivos 2009/2010,2010/2011 e 2011/2012. Foi utilizados pêssegos dos cultivares Charme e Maciel. Foi utilizado delineamento experimental inteiramente casualizados, em esquema fatorial 3 x 3 (época da poda verde x técnica de manejo da poda verde), com 4 repetições, constituindo-se cada parcela de 2 plantas. As épocas de realização da poda verde foram na terceira, quarta e quinta semanas antes da colheita. As técnicas de manejo foram primeiro, baseadas na retirada dos ramos ladrões no interior e na base dos ramos, ramos quebrados e mal posicionados e, segundo no dobramento destes, permanecendo-os ligados a planta. A campo foi avaliado a capacidade produtiva das plantas e análises fisiológicas nos ciclos 2010/2011 e 2011/2012, e em laboratório foram analisadas as características físico-química e bioquímica dos frutos. Conclui se ao final deste trabalho que o uso da poda verde em plantas de pessegueiro Charme e Maciel a cinco e quatro semanas antes da colheita, com a técnica de corte e de dobramento dos ramos proporcionou melhorias na qualidade de seus frutos. / One of the aspects that it should be considered in the fresh fruit market peach is the fruit quality. The visual aspect is the most important factor, it being the skin color relevant because it is associated with the fruit maturation and flavor. One of cultural techniques to improve the fruit quality is summer pruning, which has as main purpose to increase light penetration within the canopy tree and consequently it to promote the pigmentation, as well as improvements in the fruit flavor. However, this technique can to present results variable according to the time and manner in which it was realized. The aim of this work was evaluate the time and management type for summer pruning to obtain peach quality. The work was carried out at commercial orchard from Dois Vizinhos city, Paraná State, Brazil, in 2009/2010, 2010/2011 and 2011/2012 cycle. It was used Charme and Maciel peach varieties. The experimental design was completely randomized, in factorial 3. x 3 (summer pruning time x summer pruning management type), with 4 replications of two plants by plot. The summer pruning time were in the third, fourth and fifth week before harvest. First the cultural practices were realized removal vigorous vertical shoot inside and in the base of crown, break shoots and bad shoots position in the tree. The second in the bending shoots in the tree. The yield and physiology characteristics tree on orchard in 2010/2011 and 2011/2012 cycle and fruit physical-chemical- biochemistry variables were evaluated on Plant Physiology Laboratory. It was concluded that the summer pruning use in Charme and Maciel peach tree during four and five weeks before harvest, with the pruning and beding shoot increased the fruit quality.

Um dos aspectos que devem ser considerados no mercado de frutas frescas de pessegueiro é a qualidade de seus frutos. Considera-se a aparência como fator importante, sendo a coloração da epiderme relevante, pois se associa com a maturação e o sabor dos frutos. Uma das técnicas de manejo que visam melhorar a qualidade dos frutos é a poda verde, que tem como intuito principal de aumentar a penetração da luz no interior da copa e consequentemente favorecer a pigmentação, bem como, melhorar o sabor dos frutos. Porém, esta técnica pode apresentar resultados variáveis, de acordo com a época e a forma em que a mesma é realizada. O objetivo deste trabalho foi de determinar o período e a forma de execução da poda verde para melhorar a qualidade dos frutos de pessegueiros. O trabalho foi conduzido em pomar comercial no município de Dois Vizinhos (PR), nos ciclos produtivos 2009/2010,2010/2011 e 2011/2012. Foi utilizados pêssegos dos cultivares Charme e Maciel. Foi utilizado delineamento experimental inteiramente casualizados, em esquema fatorial 3 x 3 (época da poda verde x técnica de manejo da poda verde), com 4 repetições, constituindo-se cada parcela de 2 plantas. As épocas de realização da poda verde foram na terceira, quarta e quinta semanas antes da colheita. As técnicas de manejo foram primeiro, baseadas na retirada dos ramos ladrões no interior e na base dos ramos, ramos quebrados e mal posicionados e, segundo no dobramento destes, permanecendo-os ligados a planta. A campo foi avaliado a capacidade produtiva das plantas e análises fisiológicas nos ciclos 2010/2011 e 2011/2012, e em laboratório foram analisadas as características físico-química e bioquímica dos frutos. Conclui se ao final deste trabalho que o uso da poda verde em plantas de pessegueiro Charme e Maciel a cinco e quatro semanas antes da colheita, com a técnica de corte e de dobramento dos ramos proporcionou melhorias na qualidade de seus frutos. / One of the aspects that it should be considered in the fresh fruit market peach is the fruit quality. The visual aspect is the most important factor, it being the skin color relevant because it is associated with the fruit maturation and flavor. One of cultural techniques to improve the fruit quality is summer pruning, which has as main purpose to increase light penetration within the canopy tree and consequently it to promote the pigmentation, as well as improvements in the fruit flavor. However, this technique can to present results variable according to the time and manner in which it was realized. The aim of this work was evaluate the time and management type for summer pruning to obtain peach quality. The work was carried out at commercial orchard from Dois Vizinhos city, Paraná State, Brazil, in 2009/2010, 2010/2011 and 2011/2012 cycle. It was used Charme and Maciel peach varieties. The experimental design was completely randomized, in factorial 3. x 3 (summer pruning time x summer pruning management type), with 4 replications of two plants by plot. The summer pruning time were in the third, fourth and fifth week before harvest. First the cultural practices were realized removal vigorous vertical shoot inside and in the base of crown, break shoots and bad shoots position in the tree. The second in the bending shoots in the tree. The yield and physiology characteristics tree on orchard in 2010/2011 and 2011/2012 cycle and fruit physical-chemical- biochemistry variables were evaluated on Plant Physiology Laboratory. It was concluded that the summer pruning use in Charme and Maciel peach tree during four and five weeks before harvest, with the pruning and beding shoot increased the fruit quality.

The effect of source-sink relationships on the performance of tomato and hot pepper was investigated in glasshouse experiments by pruning tomato trusses and hot pepper fruit from plants trained to a single stem. The objectives were to characterize the effect of time, method and intensity of pruning on the yield and quality of tomato and hot pepper. Pruning at anthesis as compared to pruning at fruit-set had little effect on yield and fruit quality of both crops. Yield per truss increased steadily with intensity of pruning in tomato, due to increase in fruit size and fruit number per truss. Thus, total yield was not affected by pruning. In hot pepper fruit size increased with intensity of pruning but total yield was significantly reduced and total plant dry mass depressed at higher source : sink ratios (two and three fruit pruned out of a total of six). Occurrence of fruit disorders such as blossom-end rot and fruit cracking increased with increasing source: sink ratio. Pruning of one truss in tomato and one fruit in hot pepper gave the best fruit quality in terms of fruit size, pericarp thickness and freedom from defects, without decreasing total and marketable yield. Removing a middle truss of tomato (third truss) gave the highest yield as compared to removing the youngest truss (sixth truss) or the oldest truss (first truss). The yield increase (relative to the control) in the remaining individual trusses tended to decrease with increasing distance of the trusses from the pruned truss. In hot pepper removal of the youngest fruit (sixth fruit) resulted in the highest yield in comparison to removal of the middle fruit (third fruit) and the oldest fruit (first fruit). The quantity of yield increase in the remaining individual fruits had no consistent trend regarding the relative distance of the fruits from the pruned fruit. Two pruning methods were tried on hot pepper and tomato to compare yield and fruit quality. The first method involved pruning of the first three consecutive trusses of tomato and the first three consecutive fruit of hot pepper out of a total of six. The second method involved pruning of three alternating tomato trusses or hot pepper fruit. Yield and yield components did not differ significantly for the two methods, but pruning alternate trusses of tomato and fruit of hot pepper reduced occurrence of fruit disorders. / Dissertation (MSc (Agric) Agronomy)--University of Pretoria, 2007. / Plant Production and Soil Science / unrestricted

Philosophiae Doctor - PhD / Apple fruit quality is of utmost importance to apple farmers and breeders in the selection and commercialization of new cultivars. Fruit size, colour, texture, firmness and taste are all traits that affect the quality of fruit. In this study the genetic contribution of these traits, and others were evaluated in order to generate the genetic markers required for the application of marker assisted selection in fruit quality breeding. Three mapping populations, ‘Prima’ x ‘Anna’, ‘Golden Delicious’ x ‘Priscilla’ and ‘Golden Delicious’ x ‘Anna’, consisting of 87, 87 and 141 respectively, were used in the study. Fruit samples were analysed, using a range of visual, physical and sensory measurements, over a period of three years, and the data was then correlated using statistical analysis. Traits analysed included stripe-ness, fruit colour, fruit size, fruit form, ground colour, russet, texture, fruit firmness, juiciness, sugar content, acidity, taste, skin toughness, %TSS, fruit mass and diameter. ANOVA detected significant levels of variation between the three families for all traits except taste and russet; while highly significant ‘within family’ variation was also observed for all traits in pre- and post-storage analyses, except for sugar content (sweetness) and fruit form. Within family variation also contributed the largest percentage towards the variance components of all traits. Heritability estimates found stripe-ness to be the most heritable trait, from subjective analyses, while heritability values ranged from 0.41 to 0.84 for instrumentally measured traits. The genetic maps for the three populations were generated using both published microsatellites and new EST-SSR and DART markers, using JoinMap 4.0". The integrated genetic linkage maps of ‘Prima’ x ‘Anna’, ‘Golden Delicious’ x ‘Priscilla’, ‘Golden Delicious’ x ‘Anna’ consisted of 398 (133 SSR and 265 DArT), 353 (80 SSR and 273 DArT) and 213 (87 SSR and 126 DArT) markers respectively. The maps were 1021.6cM, 1079cM and 1302.7cM in length, respectively. Location of quantitative trait loci (QTL) for 14 fruit quality traits was detected using MapQTL 5.0" and a total of 79 pre-storage and 60 poststorage QTLs were identified on the three mapping populations. Comparative genome analysis and the role of various genes on the outcome of fruit quality can now be investigated. Using the integrated genetic maps, and the QTLs identified, candidate markers associated with these QTL can be used for marker-assisted selection, to increase the speed and efficiency of the apple breeding program.

One of the factors that maintains fruit quality is its microbial flora. Fruit holds a natural non-pathogenic epiphytic microflora but can become contaminated with pathogenic microorganisms during export, causing either postharvest decay or possibly resulting in a food safety risk. In order to study microbial dynamics on fruit surfaces and the environment fruit moves through in the export chain, fruit washings were made, surfaces were sampled and total populations and diversities determined per cm2. Hygiene and safety levels for fruit export environments were hereby determined by sampling various points along the apple export chain, which included two farms and a harbour in South Africa and two harbours, two repacking facilities and two retail centres in Europe. In this first study of its kind, all the surfaces that were sampled exceeded the international standard for cleaning efficacy of food-processing equipment that is <5 cfu/cm2, while several areas exceeded the maximum acceptable index level of microbial air contamination of 22 cfu/h in food industries. Washing of containers on a harbour in South Africa did not have a significant impact on microbial populations. Regarding fruit quality, it was determined that apple microflora fluctuate throughout the export process and that postharvest pathogens that are known to cause great economic losses in the apple industry, proved to be of little significance in this investigation. The presence of six foodborne pathogens i.e. Shigella sonnei, Salmonella muenchen, Escherichia coli, Listeria monocytogenes, Staphylococcus aureus and Staphylococcus epidermidi/s was monitored throughout the chain. Of these, only S. aureus and E. coli were recorded, although pathogenicity was not confirmed for the latter. Staphylococcus aureus was found in containers and at a retail centre in Europe, and S. aureus and S. epidermidis were recorded on apple surfaces for the first time. Escherichia coli was present in great numbers in fruit washing water on a farm in South Africa. Since the standard for food premises is very stringent and perhaps inapplicable for fresh fruit handling and holding facilities, future research should include development of a more realistic hygiene standard for fresh fruit environments. / Dissertation (MSc(Agric) : Plant Pathology)--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted

No description available.

Anaerobic soil disinfestation (ASD) is a promising alternative to chemical fumigation to control soil-borne plant pathogens and weeds. This research focused on evaluating several locally available carbon sources for ASD on weed control, evaluating the performance of brewers' spent grain (a promising carbon source) under field conditions, and evaluating whether yeast addition enhanced the effectiveness of ASD treatments. A series of greenhouse trials were conducted at the Southern Piedmont AREC (Agricultural Research and Extension Center). The greenhouse trials were conducted in PVC tubes, 20 cm tall and 15 cm in diameter. The first set of trials evaluated ASD conducted over 21-day periods of ASD using locally available carbon sources. The carbon sources included brewer`s spent grain, buckwheat (Fagopyrum esculentum), cowpea (Vigna unguiculata), paper mulch, peanut (Arachis hypogaea) shells, rice bran, sorghum-sudangrass (Sorghum drummondii), and waste coffee grounds applied at 4 mg of C/g of soil. The targeted weed species included common chickweed (Stellaria media (L.) Vill.), redroot pigweed (Amaranthus retroflexus L.), white clover (Trifolium repens L.), and yellow nutsedge (Cyperus esculentus L.). All ASD treatments significantly reduced weed viability compared to the non-treated control. The yeast amendments enhanced weed control over ASD without yeast. The second set of greenhouse trials was focused on ASD using brewer`s spent grain, and on evaluating ASD at the half and one-third carbon dose rates. The target pests were the same weed species in the first set of trials, and Pythium irregulare was added as an additional target pest. This set of trials indicated yeast enhanced addition the effect of BSG in ASD on both weeds and P. irregulare, indicating the potential to reduce carbon input necessary for effective ASD. A follow-up, two seasons, open-field trial conducted over two growing seasons at the Hampton Roads AREC focused on understanding the effects of ASD on weed density and strawberry fruit yield and fruit quality in annual hill strawberry production. The treatments included ASD at standard or half carbon dose rates, with or without yeast. Fumigation (80% chloropicrin + 20% 1,3-dichloropropene) and non-treated plots were used as control groups. Weed suppression with ASD was consistent for most of the broadleaf weed species, and total weed counts were significantly reduced compared to non-treated controls. Yield from ASD with yeast was higher than ASD without yeast and non-treated control in one growing season, while the increase in yield did not occur in another growing season. Yeast may have potentially enhanced the yield effects of ASD but lacked consistency. Yeast may have the potential to enhance ASD effectiveness. / Doctor of Philosophy / Strawberry is a high-value crop known for its brightly colored, sweet tasting, juicy and fleshy fruit that possesses a unique aroma. The southern region is the second large region of strawberry production in the United States. Strawberry is susceptible to soil-borne pests, including weeds and diseases. Preplant control of soil-borne diseases and weeds is important for strawberry production. Early season weeds can compete with newly transplanted strawberry plugs for nutrients, light, and other resources. However, currently, the limited options of pre-plant chemical fumigants and herbicides available in strawberry plasticulture make weed control a challenge in strawberry production. Anaerobic soil disinfestation (ASD) may be an effective alternative to preplant chemical fumigation. Anaerobic soil disinfestation involves three steps- applying carbon sources to the soil, covering the bed with black tarp, and watering the soil to maintain certain soil moisture to field capacity generally for 21 days. However, there are only a few studies on weed control using ASD in the southern region; locally available carbon sources also need to be evaluated. Thus, this study focused on evaluating several locally available carbon sources (cover crops, brewer`s spent grain, used coffee ground, paper mulch, peanut shell) for ASD to control troublesome weeds (common chickweed, redroot pigweed, white clover, yellow nutsedge). This study also explored a new method that involves mixing distiller's yeast with solid carbon sources in order to enhance the ASD weed control effect. Additionally, this study evaluated the effect of ASD using reduced carbon inputs, potentially reducing the total cost of ASD by reducing the carbon input. A series of greenhouse studies were conducted at the Southern Piedmont Agricultural Research and Extension Center (AREC), Blackstone, VA, with a follow-up field study done at the Hampton Roads AREC. The greenhouse trials evaluated carbon sources including brewer`s spent grain, buckwheat, cowpea, paper mulch, peanut shells, rice bran, sorghum-sudangrass, and waste coffee grounds. These greenhouse experiments were conducted in containers made from PVC tubes, and strawberry plants were not involved. The main objective of the greenhouse trial was to test the suppression of four troublesome weeds, including common chickweed, redroot pigweed, yellow nutsedge, and white clover. The most effective treatments in the greenhouse studies were further investigated in the field trial. The brewer`s spent grain was again used in the field trial, and treatments included ASD using a full or half dose of brewer's spent grain, with or without yeast. We evaluated the effects of these treatments on weed control, plant crop growth, and crop yields. Fruit quality factors, including fruit firmness, sweetness, and size, were also evaluated. In summary, all of the carbon sources evaluated provide similar weed control. Adding yeast showed potential to enhance the effect of ASD using brewer`s spent grain. Adding yeast also increased the effectiveness of the half-rate of the carbon source, showing the potential for effective pre-plant pest control for strawberry using ASD treatments with significantly reduced C dose rates.

Ultrasonic techniques were investigated for non-invasive quality evaluation of selected fruits and vegetables. An ultrasonic non-destructive evaluation system was developed and used to investigate physical and acoustical property changes for the selected fruits and vegetables non-invasively. The system included a high power burst pulser, a broadband receiver, a digital storage oscilloscope, two pairs of transducers of 250 kHz and 1 MHz, and a microcomputer system, which was interfaced with the ultrasonic equipment through a General Purpose Interface Board (GPIB), for data acquisition and analysis. Using potatoes and apples, several forms of the acoustic indices were investigated using the system. Investigation of “Yukon-Gold’ potatoes concentrated on the physical and acoustical property changes during the storage period of approximately five months. The tests were conducted at regular intervals. Ultrasonic velocity, attenuation coefficient, modulus of elasticity, and tissue density were determined for each potato along two different orientations — longitudinal and transverse. Three varieties of apples, ‘Golden Delicious’, ‘Red Delicious’, and ‘Granny Smith’, were tested to detect their physiological changes with ripeness. The tests were conducted at two different stages of ripeness. In each test, ultrasonic velocity, attenuation coefficient, modulus of elasticity, and tissue density were determined along longitudinal and radial directions of the apples. Frequency analysis of the transmitted ultrasonic signals through potato and apple samples was also conducted using Fast Fourier Transform (FFT) techniques. The experimental results for the potatoes and apples indicated the measured acoustical and physical properties differed along different orientations; i.e., potato and apple tissues are anisotropic materials. Apple tissues transmitted much lower frequency components than potato tissues and the transmitted frequency range was much narrower due to the much higher percentage of intercellular void space in apple tissues (24%) than in potato tissues (2%). The ultrasonic measurements were able to detect physiological changes and physical heterogeneities in fruit and vegetable tissues. Therefore, the ultrasonic technique can be a useful and quick method for evaluating firmness as well as textural and rheological property changes during storage of fruits and vegetables. Hollow hearts in ‘Atlantic’ potatoes were successfully detected using the ultrasonic nondestructive evaluation system at 250 kHz. A objective this work was to develop a quantitative, non-invasive method for hollow heart detection in potatoes, and to provide information for designing evaluation equipment which could serve as an automatic quality control step in the production process. The analysis of the transmitted ultrasonic signals through the potatoes was carried out in both time and frequency domains. The results of the investigation of ‘Atlantic’ potatoes showed that the waveform of transmitted ultrasonic signals through a hollow heart potato differed significantly from that of a normal potato. Further, the defective potatoes could be separated on the basis of the amount of ultrasonic power transmitted through a potato. By means of digital Fourier analysis, the 0^th spectral moment, M₀, was determined from the power spectral density curve of a transmitted ultrasonic signal. The spectral moment represents the amount of ultrasonic power transmitted through a tested potato, and was chosen as the basis for quantitative, non-invasive method for hollow heart detection, since power transmission of ultrasonic wave was affected by the presence of hollow heart in potatoes. Potatoes with hollow heart transmitted much less ultrasonic power than normal potatoes — approximately 89% less on average. There was a distinct separation between the normal potatoes and hollow heart potatoes. The reliability of this method was confirmed. Among 41 ‘Atlantic’ potatoes tested, all 26 hollow-heart potatoes were identified without exception. Therefore, the parameter M₀ could provide an effective method of analyzing the ultrasonic measurements for quantitative, non-invasive evaluation of hollow hearts in potatoes. This non-invasive method could be used to identify internal quality of potatoes that is difficult to evaluate from external appearance. Such a measurement offers promises for the development of equipment that would sort potatoes with hollow heart automatically. / Ph. D.

Two experiments were conducted to determine the influence of light on 'Norman' and 'Cresthaven' peach fruit quality characteristics. Of primary interest was the relationship between ground color and flesh firmness. Light levels were manipulated by use of shade cloth, reflective mulch, and aluminum foil. 'Norman' trees, with a randomly chosen half of the canopy covered with 73% shade cloth, had fruit with lower levels of red color, soluble solids concentration (SSC), specific leaf weight, and average photosynthetic photon flux (PPF) than did non-shaded trees. Foil-covered 'Cresthaven' fruit were larger, less firm, and had lower SSC than non-covered fruit. Covered fruit developed yellow but not red color. Position of the fruit within the canopy of the tree also affected fruit quality characteristics. Inside fruit on both 'Norman' and 'Cresthaven' trees were smaller and firmer, had lower SSC, and were less red than fruit from the canopy exterior. The position effect was probably due to the degree of light exposure and not to the distance from the roots. Fruit on the inside of the tree canopies received much lower average PPF than outside fruit. Relationships were evaluated between ground color and firmness for both cultivars. At a given hue angle, fruit developing in high-light environments were firmer than fruit from low-light environments for 'Cresthaven', but the opposite was true for 'Norman'. Therefore, canopy position or the light environment in the vicinity of the developing fruit does not consistently influence the relationship between hue angle on the non-blush side of the fruit, and flesh firmness. / Master of Science