Date of Award

Spring 5-2011

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Committee Chair

Kenneth Curry

Committee Chair Department

Biological Sciences

Committee Member 2

Mac Alford

Committee Member 2 Department

Biological Sciences

Committee Member 3

Donna Marshall

Abstract

Rain-related splitting of blueberry fruit is a problem facing growers in the southeastern United States and causes an estimated profit loss of up to 20% ($300- $500 per acre). Studies of this phenomenon in other thin-skinned, soft, fleshy fruit showed that no single or set of related physiological or anatomical property explained splitting. Similar research on blueberry fruit was inconclusive, thus a different approach was suggested. l sampled five cultivars at various stages of development distributed across acknowledged split-resistant (SR) and split-susceptible (SS) categories including both rabbiteye and southern highbush types. Several developmental studies were completed at the light microscope level that allowed us to analyze apoplast to symplast ratios (A:S ratio) and thus allowed a study of anatomical features that should be strongly influenced by physiological/hydrostatic phenomena. Several hypotheses of A:S ratios were tested resulting in the observed correlations that (1) at the attachment end of the fruit, the SR ratios were lower than the SS ratios and (2) at the floral end, the SR ratios were bracketed by the SS ratios. These correlations are consistent with an interpretation that (1) a higher A:S ratio increases the amount of hydrophilic (wall) material for water uptake and (2) extremes in A:S ratios compromise the structural integrity of the fruit tissue.

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