D.Sc. (Botany) / Please refer to full text to view abstract

An investigation was carried out in order to evaluate some of the factors which influence the use of dwarf and semi-dwarf apple trees in commercial orchards in the Okanagan Valley of British Columbia. Three determining factors were found to be of prime importance: the planting density of the trees in the orchard, the tree form as determined by the pruning and training system carried out and the nature of the rootstock used. In the Doornberg Orchards at Okanagan Centre where the experiments were conducted, semi-dwarf trees on Malling VII rootstock trained as hedgerows and planted at a high density per acre gave the optimum earliest and total yields and returns. The experiments were carried out from planting time up to the end of the sixth growing season. The variety of apple used in the experiment was Golden Delicious. / Land and Food Systems, Faculty of / Graduate

Investigations were made of the association among megagametogenesis, pollen morphology, and seed production in two irradiated apple varieties, Golden Delicious and McIntosh, and in two years, 1964 and 1965. In each year eight to ten clones of each variety were selected on the basis of low, medium, and high pollen abortion. Untreated and treated Golden Delicious and McIntosh clones with normal pollen production, approximately 90% and 50% respectively, had the highest proportion of embryo sacs at the differentiated 8-nucleate stage, and the smallest proportion of embryo sacs at the 2- and 4-nucleate stages. Irradiated clones with the least normal pollen had the highest proportion of immature 2- and 4-nucleate embryo sacs. With both varieties and in both years reduced pollen fertility was positively correlated with retarded embryo sac development. Check clones with high pollen fertility had the highest number of developed seeds per fruit and irradiated clones with reduced pollen fertility had the smallest number of developed seeds per fruit. The number of developed seeds per fruit was positively correlated with the proportion of mature 8-nucleate embryo sacs. The reduction in seed numbers in irradiated apple clones with reduced pollen fertility may be explained, in part, by retarded embryo sac development. / Land and Food Systems, Faculty of / Graduate

Bacterial pathogens on the surfaces of raw produce may be difficult to remove for identification and enumeration. The first part of this project examined whether ultrasonic treatment (40 kHz) of a rinse solution would enhance recovery of Salmonella spp. from various produce surfaces. Strawberries, apples, and cantaloupe were surface inoculated with a five-strain cocktail of nalidixic acid resistant Salmonella spp. Samples were subjected to one of six different treatments using different combinations of agitation methods (manual shaking or ultrasound), diluent temperatures (25°C and 40°C), and agitation times (60 and 120 seconds). After treatment, diluent was spiral plated onto tryptic soy agar supplemented with 50 ppm of nalidixic acid and plates were incubated at 37°C for 48 hours. Results from this study indicate that ultrasonic treatment of a rinse solution did not enhance or diminish recovery of Salmonella spp. from produce surfaces, as compared to manual agitation. The effects of diluent temperature and exposure time appeared to have a significant effect on recovery, depending on the type of produce. The second part of this project used a computer imaging system to determine the surface area of various types of produce. The imaging system acquired and stored multiple images of the produce samples. From these images, surface fitting and approximation of a 3-D wire frame model were used to calculate surface area. From these measurements, it was determined that there were statistical relationships between surface area and weight. Surface area measurements were used to develop equations to predict surface area from weight measurements. / Master of Science

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