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

The purpose of the study is to determine which factors contributed to the production of apples in the Okanagan area during the year 1969. Regression analysis is used in an attempt to quantify yield relationships. A comparison is made among different tree-size categories in order to determine whether it is necessary to fit separate regression equations instead of using the data for the three groups in a single regression equation. For this purpose an Equality of Slope Test is performed. The outcome of the test shows that there are no significant differences among corresponding coefficients in the equations for tree-size categories. Hence it is feasible to combine them into one equation. For the regression analysis, two different types of yield relationships are employed: one is a Cobb-Douglas function linear in the logarithms and the other is a quadratic function. Both functions include a dependent variable, namely, yield per acre and seven independent variables; that is, density, age, value of fertilizer applied, value of spray applied, pruning and thinning labour hours, geographical dummy, and tree-size index. These independent variables are measured on a per-acre basis except in the case of age, geographical dummy and tree-size index. The data, which consists of cross-section informa- tion for 1969 represents one hundred and nineteen sample apple plots. It was derived from personal interviews with apple growers. The quadratic function poses a problem arising from cross-terms in the equation. It was necessary to modify the function in such a manner that the cross-terms included in the regression equation were justified on biological or economic grounds. The regression results for each type of function used in the analysis are discussed and estimates of coefficients and related standard errors shown. It seems desirable that data should be broken down into apple variety groups because different varieties of apple may well have distinct bearing characteristics. Apple trees in the specific plots under study, however, are made up of a mixture of varieties, thus it is extremely difficult to draw a clear map of acreages occupied by each variety. In attempting to obtain variety data, notwithstanding the mixture of varieties in stands, the original data is broken down under certain assumptions. Also in decomposing apple yields into grade constituents similar problems arise. Despite these difficulties, tests of differences among average yields are made under stated conditions for varietal, tree-size, apple-grade, and regional categories. These tests reveal that there are no significant differences in average apple yields for varieties, apple grades and regions., but there are significant differences in the case of different tree sizes. The results of these Tests are presented in Chapter VI. The quadratic form of function seems, within the theoretical framework, to be able to represent satisfactorily the apple yield relationship with the selected independent variables. But, in practice, it does not conform well to the empirical situation; it produces a serious multicolline-arity problem from the point of view of statistical inference. The Cobb-Douglas function, however, does not cause such a problem. Apart from this, its application brought in almost all the coefficients corresponding to the basic independent variables except for the coefficient of the tree-size index variable. On this evidence, a tentative conclusion was made in favour of the Cobb-Douglas function for the representation of an apple yield relationship in the Okanagan in 1969. / Land and Food Systems, Faculty of / Graduate

The influence of freezing rate, rate of heat input and drying chamber pressure on freeze-drying rate was studied to determine the thermal and physical properties of MacIntosh apple and Netted Gem potato tissue. The samples were frozen either by immersion in dry ice and ethanol (fast frozen) or by placement in a refrigerated cabinet maintained at a temperature between -10° and +5° F (slow frozen). The samples were suspended in a chamber maintained at a pressure of 550 or 1400 microns of mercury and surrounded by a constant temperature water bath which provided a radiant heat source of 86° or 104°F. The weight, and the surface and centre temperature of the sample were recorded continuously during freeze-drying. Vapor diffusion was the rate limiting factor for fast frozen samples while heat transfer was rate limiting for slow frozen samples. Chamber pressure had little influence on the freeze-drying rate of slow frozen samples. Potato tissue thermal conductivity varied from 0.66x10⁻² BTU/Hr.°F Ft. at a pressure of 550 microns to 0.78x10⁻² at 1400 microns. The thermal conductivity of apple tissue was 1.0 x 10⁻² BTU/Hr.°F Ft. at both pressures. The eutectic temperature of apple and potato tissue was found to be -10°F and -1°0F. respectively. / Land and Food Systems, Faculty of / Graduate

This thesis examines the relationship between water and yield for apples in the Okanagan region of British Columbia. This is accomplished through a model which simulates the water/yield relationship in tree fruits. Two soil types, two rootstocks, and two irrigation systems were included in the simulation. The results of the simulation indicate that Okanagan orchard irrigation water requirements are substantially lower than present irrigation application rates. Using sprinkler irrigation, irrigation requirements for silt-loam soils amounted to 30% of present application rates, while for sand soils 42% of present application rates were required. Trickle irrigation requirements were determined to be 71% of sprinkler requirements for similar yields. / Land and Food Systems, Faculty of / Graduate

Factors affecting the centrifugal separation of apple parenchyma cell serum were investigated for three important cultivars from the Okanagan Valley of British Columbia; Mcintosh, Red Delicious, and Winesap. The factors studied included cultivar, maturity, maceration treatment, and centrifugation time and speed. Observations included yield of cell serum, relative serum clarity, pulp and serum viscometric properties, alcohol insoluble solids, soluble solids, serum pH, particle size and tissue firmness. The pulp viscometric property, viscosity at a shear rate of 100 sec⁻¹, was the observation which primarily influenced juice yields. The increased separation obtained for Mcintosh > Red Delicious > Winesap was attributed to pulp viscosity values. Relative serum clarity was influenced by serum soluble solids when centrifugation time was constant at six minutes or by the serum pH and pulp viscosity at maturity one (0 storage). Increased centrifugation speed and time markedly improved the yield of cell serum for the factors evaluated. Maceration treatments reduced the average particle diameter from 330 μm to 229 μm and the pulp viscosity values. At 5,500 and 8,000 rpm, higher yields were obtained when the particle size was small. At 10,500 rpm or 14,500 rpm, higher serum yields were obtained with larger particle sizes. Consideration of the particle size (> 100 μm) and shape (non-spherical), along with sedimentation theory indicated the separation followed Newton's Law. The high yields obtained with the larger particle size at high rpm confirmed a low drag force coefficient (C[sub D] = .5). Although a slight reduction in particle size and viscosity was observed when parenchyma tissue was subjected to ultrasonic vibration, no improvement was obtained in serum yield or clarity. The centrifugal separation of apple parenchyma cell serum was shown to be feasible. The efficiency of the separation improved as pulp viscosity decreased and speed or time of centrifugation increased. The tissue particle size evaluated was of secondary importance for the separations observed. / Land and Food Systems, Faculty of / Graduate

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