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Relationship Of Critical Photoperiod Of Short-Day Parents To Frequency Of Day-Neutral Progeny In Short-Day X Day-Neutral Crosses Of Fragaria X Ananassa, Christina Marie Cundari

Doctoral Dissertations

Critical photoperiod for flowering was determined for short-day (SD) and day-neutral (DN) genotypes of strawberry used in SD x DN crosses to investigate whether variation in critical photoperiod contributes to variation in frequency of DN progeny and, hence, may be an effective selection criterion for screening SD genotypes for use as parents in breeding regionally-adapted DN cultivars. Twelve SD and four DN genotypes were grown in controlled environments under eight photothermal regimes (four photoperiods (9, 11, 13, 15 hr) x two day/night temperatures (19/14 and 24/19$\sp\circ$C)). Among the SD genotypes, critical photoperiod varied more under cool than warm regimes. Under …

Competition And Dispersal In The Regulation Of Plant Species Richness On Carex Stricta Tussocks, Leonard Alexander Lord

Doctoral Dissertations

Many wetland plant species can be found growing on Carex stricta Lam. (tussock sedge) tussocks in freshwater marshes. Based on Grime's model of plant species richness, the objectives of this research were to: (1) examine if dispersal characteristics vary among C. stricta marshes in a manner that could potentially influence species richness on individual tussocks, and (2) examine how variation in propagule availability may interact with standing crop and leaf litter to regulate species richness on individual tussocks. All of the research was conducted in southeastern New Hampshire.

Dispersal characteristics were quantified in five wetlands representing a broad range of …