Date of Award

Fall 2007

Project Type

Thesis

Program or Major

Plant Biology

Degree Name

Master of Science

First Advisor

Rosanna Freyre

Abstract

Nolana L.f. is a large, diverse genus in the Solanaceae endemic to coastal deserts of Peru and Chile. Large showy flowers and drought tolerance give Nolana great potential for breeding and cultivar development for the ornamental plant industry. As a precursor to breeding efforts, studies of floral development, sexual compatibility, and seed germination were conducted involving eight Nolana species (N. adansonii, K aticoana, N. elegans, N. humijusa, N. ivaniana, N. laxa, N. plicata, N. rupicola) cultivated at UNH.

Stigma receptivity and pollen viability were evaluated at a range of stages of flower development. Floral development keys were developed to provide visual reference correlating morphological appearance of buds/flowers at each developmental stage to stage durations and levels of stigma receptivity.

Artificial hybridizations (self-, infra-, and interspecific) were performed within and between each species. Species were generally self-incompatible. Intraspecific compatibility was high. Success of interspecific hybridization was analyzed based on fruit set, mericarps per fruit, mericarp size, and seed germination. Reduction in interspecific fertility was generally seen as lower fruiting success and smaller mericarp size as compared to intraspecific hybridization. Estimated seed counts were made by x-ray analysis of mericarps revealing differences in seed set between crosses. Hybrid seed was germinated verifying compatibility of 22 unidirectional species pairs.

Causes and remedies for low seed germination rates were investigated with analysis of mericarp, morphology, imbibition, and effect of chemical and environmental germination treatments. Scanning electron microscopy and imbibition studies ruled out presence of physical germination barriers. Gibberellic acid (1000 ppm) effectively increased germination in some species. Older mericarps (stored dry for two years) had higher germination than fresh mericarps. Mericarps of N. aticoana stored for seven weeks at 35°C and 75% RH showed higher germination than mericarps stored dry, or stored moist for 1-6 or 8-12 weeks. Germination of seed cultured when immature did not surpass that of mature seed. X-ray analysis confirmed existence of at least one seed within most mericarps. Germination rates fall far below theoretical potentials based on x-ray seed counts. Findings suggest germination failure is likely due to physiological dormancy rather than low seed set.

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