Theses and Dissertations

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Theses and Dissertations (Department of Plant and Science)

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Browsing Theses and Dissertations by Subject "hybrids"

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    Genetic and Environmental Analysis of Vegetative and Yield Traits in the Oil Palm ( Elaeis Sp.).
    (Obafemi Awolowo University, 1986) Opeke, Bolanle olufunmilayo; Fakorede, M. A. B
    A total of 21 hybrids of oil palm consisting of four Elaeis,guineensis palms selected for shortness, three F1 interspecific hybrids (Elaeis oleifera x E. guineensis), 13 hybrids from the first backcross gene-ration (BC1) of the F1 interspecific hybrid crossed to E. guineensis and a standard cross used as check, were evaluated for yield and vegetative traits with a view to determining a suitable breeding method for short-stemmed palms. Associations among all traits were also investigated. Furthermore, the effects of climatic factors on vegetative and yield traits were investigated using correlations, stepwise multiple regression and path coefficient analyses. In addition, two environmental indices (biological and biophysical) were compared for yield stability using nine Dura (D) x Tenera (T) hybrids. Data for evaluation were collected from three field plantings made at the Nigerian Institute for Oil Palm Research near Benin City, between 1960 and 1969; and data collected covered the period 1963 to 1982.Generally, the backcross hybrids were superior in cumulative' trunk height and annual trunk increment compared to E. guineensis palms selected for shortness, the F1 interspecific hybrids and the check. However, average yield (as measured by fresh fruit bunch yield) of the backcross hybrids was 22.8-48.2% lower than the mean of the F1 interspecific hybrids. Number of bunches and mean bunch weight were associated with vigor characteristics (trunk height, crown diameter and number of leaves) in the backcross hybrids. Total sunshine hours and minimum relative humidity at about 18-21 months before harvest demonstrated the strongest associations with number of bunches and fresh fruit bunch yield. Generally, progenies maintained their relative ranking for environmental response regardless of the index used to quantify the environment.
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    Genotype X Environment Component of Variance and its Implications in Maize (Zeamays L.) Yield Trials.
    (Obafemi Awolowo University, 1985) Adisa, Aramide Omolara; Fakorede, M. A. B.
    Grain yield data obtained from yield trials conducted in 1981 and 1982 for five open-pollinating cultivars and eight varietal hybrids of maize (Zea mays L.) were used to investigate the effectiveness of 3 different yield trial methods. These included experiments A: 2 years, 2 locations, 1 planting date; experiment B: 1 year, 2 locations, 3 planting dates, and experiment C: 2 years, 1 location, 3 planting dates. Variance components were obtained for each method and optimum combinations of numbers of years, locations, planting dates and replications for varietal testing were determined by calculating theoretical standard error of the mean (SEM). Analysis of variance for the three methods showed highly significant location, year, planting date and genotype effects. SEM of 0.256 was obtained for 2 years, 2 locations, 1 planting date and 4 replications, and this was used as the standard for comparing the other two methods. When planting dates were substituted for years in experiment B, the SEM of 0.256 was obtained for combinations ranging from 1 year, 8 locations, 2 planting dates and 1 replication, to 1 year, 2 locations, 2 planting dates, and 4 replications. Substituting planting dates for location in experiment C however, resulted in the use of a larger number of planting dates than in experiment B, and not less than a 1-year period of testing to obtain the minimum SEM of 0.256. Planting dates can therefore be effectively substituted for years in order to reduce the time for conducting preliminary maize yield trials. Planting dates can also be substituted for locations where funds but not time, are limiting.