Masters Dissertations

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Browsing Masters Dissertations by Author "Ayiseni, Daniel Aliosa Ronson"

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    Yield component inter relations and heritability estimates in soyabean [Glycine Max (L...) Merrill]
    (University of Dar es Salaam, 1982) Ayiseni, Daniel Aliosa Ronson
    Three experiments were conducted at the University Farm, Morogoro during the 1981 Cropping Season. The first two experiments (each involving 11 soyabean varieties) aimed at obtaining information on the magnitude and extent of genotype x environment interaction, and at examining the interrelations between selected characters and yield. An F2 population derived from Bossier x IH 192 cross was utilised in the third experiment to study the pattern of inheritance and estimate heritabilities for yield and other selected characters. The first two experiments gave highly significant varietal differences for all characters. Similarly, sowing date differences for all characters were highly significant except for days to fifty per cent flowering in the second experiment. Fertiliser effects were generally significant for several characters including days to fifty per cent flowering days to maturity, 100 seed weight and seeds per pod. Variety x sowing date interactions were predominantly no significant while variety x fertiliser interactions were mostly significant for vegetative characteristics. Associations between characters and yield per plant in the first experiment were on the whole erratic, varying from one environmental regime to another while more consistent and significant relationships were obtained from experiment 2. Genotypic correlations were generally higher than phenotypic associations. Overall correlations among morphological characteristics were positive and highly significant but their associations with reproductive characters were negative. Path analysis revealed that yield was positively associated with all the selected characters except days to fifty per cent flowering and time to maturity. Both simple correlation and path analyses identified pods per plant and 100 seed weight as important yield components. While the former ranked harvest index as a third important yield component, the latter identified seeds per pod as an alternative. Days to fifty per cent flowering and maturity had strong positive indirect effects on yield per plant via pods per plant. Estimates of heritability varied from 23.0% for seeds per plant to 61.0% for 100 seed weight and these were generally in agreement with values reported in literature. Important yield components such as pods per plant (28.0%), seeds per pod (42.0%) had low to moderate heritability values. Partial dominance was found for plant height, pods per plant and harvest index while number of mainstream branches, height to first pod and yield per plant displayed over dominance.