[No abstract available] / Land and Food Systems, Faculty of / Graduate

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Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Adelaide, Dept. of Agronomy and Farming Systems, 1997. / Includes bibliographical references (leaves 190-212).

Thesis (Ph.D.)--University of Western Australia, 2005.

Recently developed methods of growth and yield analysis were applied to the results of a field experiment to determine (i) the effect of seed inoculation on the growth and yield of two cultivairs of garden pea (Pisum sativum L.) - 'Dark Skin Perfection' (DSP) and 'Early Frosty' (EF), (ii) the physiological basis for yield variability and (iii) the dynamics of reproductive growth in the pea. Seed inoculation had no noticeable effect on yield. There were, however, significant cultivar differences--DSP was larger, matured later but had lower yields than EF. Growth analysis revealed that these differences were due to the extended vegetative growth phase, higher leaf area ratio and lower harvest index of DSP. Further analysis indicated that EF had a more efficient growth strategy, as the maximum rate of partitioning of dry matter into the reproductive structures coincided with high leaf activity. By contrast maximum sink activity in DSP occurred during leaf senescence. Stem length, average leaf area and inverse leaf weight ratio were the main components of biomass variability. Yield variation, however, was affected indirectly by stem length, average leaf area, reproductive effort and average seed weight, and directly by the number of nodes, pod set and inverse leaf weight ratio. These results imply that the supply of photosynthetic material is important for increased pea yields. Significant negative correlations between vegetative components and average seed weight suggest compensation and competition between these components. Thus, yield improvement may be attainable by (1) enhancing the component which is unaffected by this compensation or (2) reducing the competition by shifting the equilibrium. Two crucial periods when source supply may affect yield were detected during the reproductive phase. The first period (61 days after planting in DSP and 55 days after planting in EF) was more pronounced in DSP. In the second phase (day 75 for DSP and 65 for EF) seed growth became important and seemed to influence leaf activity. This finding suggests that the rate of canopy establishment is as important as the rate of pod filling for improving yields. A dynamic model simulating pod yield in relation to source supply is outlined. / Land and Food Systems, Faculty of / Graduate

Peas (Pisum sativum) are an important constituent in the diet of many people. Peas may be cooked and eaten as green peas shortly after harvest, stored for short periods in the pods, or, after suitable treatment, stored for long periods before consumption. Many factors influence the yield and quality of frozen peas but maturity requires careful consideration because of the relation of maturity to color, flavor, and texture. The objectives of this thesis were to determine the effect of the maturity stage on the quality of the frozen peas during processing and storage and to correlate the interactions between the sensory evaluation panel with the physical and chemical quality factors measured. Venus pea variety grown under commercial conditions at the Sublimity area east of Salem, Oregon, were used in this study. The trials were randomized, for three stages of maturity with three replications per each stage of maturity. Each of the three maturity stages was harvested; vined; blanched by steaming at 98.8°C (210°F) for 30 sec for the immature peas, 60 sec for the mature peas, and 90 sec for the overmature peas; frozen at -37.2°C (-35°F) for 24 hr in an air blast freezer and stored at -23.3°C (-10°F) for 4 and 8 month. During processing and. storage the following factors were determined: tenderometer value, total solids, alcohol insoluble solids, peroxidase activity, ascorbic acid., total sugars and sensory evaluation. In the sensory evaluation analysis starchiness, sweetness and tenderness intensity, as well as texture, flavor and overall desirability were measured. Analysis of variance and least significant difference were used to compare the effect of pea maturity during processing and storage on the different quality factors measured. Correlation coefficients were used to determine the relationship between these factors. Immature peas had lower tenderometer value than overmature peas. Tenderometer value of peas decreased, during processing. The highest total solids content was observed, in the overmature peas and the lowest total solids content in the immature peas. This behavior was also observed in the alcohol insoluble solids content. Raw peas in the three maturity stages had the same initial peroxidase activity and the significant effect of the maturity level found in the residual peroxidase was affected by the different blanching time applied at each maturity stage. The ascorbic acid content was significantly affected, by the maturity level and was reduced during the blanching treatment. Total soluble sugar content was higher in immature peas and lower in overmature peas. All the sensory evaluation parameters measured were affected by the maturity. In general, the taste panel found higher flavor desirability on the mature peas but when texture and overall desirability were measured immature and mature peas were equally preferred. Significant correlations were found between physical, chemical, and sensory parameters analyzed, some of them are tenderometer value and alcohol insoluble solids; total solids and alcohol insoluble solids; alcohol insoluble solids and overall desirability. / Graduation date: 1981

The problem in green pea grading system by using brine flotation is loss of some less mature peas (generally regarded as higher in quality and price) in the sinker fraction (lower quality). Green peas were sampled from the production line as follows: (1) blanched but ungraded peas, (2) floater fraction, and (3) sinker fraction. Peas from the floater and sinker fractions were tested using the standard brine flotation test (United States Standards for Grades of Frozen Peas, 1959). Using sodium chloride salt brine as the separation medium, the blanched but ungraded peas were used to test the effect on percent floaters caused by: (1) change in brine concentration, (2) change in brine temperature, (3) change in pea temperature. Again, the blanched but ungraded peas were used to test the effect of underskin air on percent floaters, using sucrose syrup as the separation medium. The relationships between change in percent floater peas and maturity of the floater and sinker fractions were determined by using Alcohol Insoluble Solids (AIS) analysis as the maturity reference method. The nature of problem was identified, when a high percent (44.9%) U.S. Fancy grade floaters was found in the sinker fraction from the factory. The study showed that the percentage of floaters was significantly (p=0.05) influenced by brine concentration, brine temperature, pea temperature, and retention of air under the skin of the peas. Regression analysis of the data for the first three factors indicated that rate of change in percent floaters was greatest with brine concentration, and least with pea temperature. The change in maturity of floater and sinker fractions as determined by AIS analysis showed a close positive relationship between the change in percent floaters produced by change in the treatment conditions. Again, AIS results showed that residual underskin air in the intact blanched peas significantly affected the accurate separation by a false increase in buoyancy of borderline maturity peas (AIS was in between floater's and sinker's) in the flotation process. The underskin air factor was the least important factor affecting percent floaters when compared with the other factors of brine concentration, brine temperature, and pea temperature. / Graduation date: 1985

Thesis (Ph. D.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Dec. 21, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Plant Science, Department of Agricultural, Food and Nutritional Science, University of Alberta." Includes bibliographical references.

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