Date of Award

1987

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Abstract

A study was undertaken to examine fecundity and floral ontogeny in wild type (WT) and tissue culture-derived (TC) plants of Hibiscus acetosella Welw. ex Hiern. Twenty-eight plants regenerated in vitro from somatic embryos were outplanted and established in the greenhouse, as were three WT plants from seed. The TC and WT plants were self-pollinated. Nine of the TC plants were self-fertile but exhibited a reduction in fruit set and seed set when compared to WT. Days to maturity for fertile fruit varied significantly among TC plants. There was no correlation of days to maturity and number of seed set. Days to abortion of nonfertile fruit varied significantly among TC plants. Data suggested both pre- and post-fertilization, self-incompatibility barriers were present in the TC plants. Comparison of days to abortion for self-pollinated fruit and days to abortion for emasculated flowers indicated that pre-fertilization barriers to fertility occurred within eight to ten days of pollination. The centripetally initiated floral organs in WT consisted of seven to ten bracteoles, five sepals with a congenitally connate basal tube and free terminal lobes, five petals, a connate androecial tube bearing numerous centrifugally initiated stamens in two rows opposite each petal, and five carpels with a connate ovary base, postgenitally fused compound style, and five stylodes. The sepals were valvate in bud, the petals convolute. The number of floral organs in the TC plans varied significantly: fewer stamens than in WT; all other organs either higher or lower than WT. The TC plants had abnormalities in primordia size, relative position within and between whorls, sepal and petal aestivation, connation of the calyx and androecial tubes, and postgenital fusion of the styles. Centripetal organ initiation between whorls, centrifugal androecial primordia initiation, and connation of the gynoecial tube were not affected. Petalody of the androecium occasionally was observed. Ovule formation on the androecial tube was common and paralleled gynoecial ovule development. The androecial ovules contained functional-appearing embryo sacs.

Pages

143

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