Effect of desiccation and storage on the seeds of two related species in the Amaryllidaceae from the western Cape Province
Bachelor Thesis
1993
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University of Cape Town
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This paper reports results on the first detailed physiological study undertaken on potentially recalcitrant seeds from the western Cape. Germination and dehydration behaviour of two related monocots Boophane flava Barker ex Snijman and Amaryllis belladonna L. (Amaryllidaceae) were studied to determine whether these seeds are indeed recalcitrant, and if so their degree of tolerance, and to gain an understanding of the reproductive strategies of these species through their seeds behaviour. Seeds were stored under mildly desiccating conditions, moisture content was determined at regular intervals and the ultrastructure of the hypocotyl apex tissue was examined. Both species are shed at high moisture content in a metabolically active state, and are able to tolerate considerable loss of this water (420-120% for B.flava) before water contents became lethal. Nevertheless, seeds were killed at high water contents a characteristic typical of recalcitrant seeds. A.belladonna seeds showed increased levels of subcellular organization during storage despite low viability scores. B.flava seeds showed hypocotyl extension and in a few instances roots and shoots were produced in storage, they began to lose viability after 8 weeks in storage at a moisture content below 120%. B.flava is a moderately recalcitrant seed species, with a slow germination rate. Although hypocotyl extension occurs in store, the onset of cell division and axis differentiation is delayed and occurred only . occasionally in store. This is interpreted as being ·a strategy to halt subcellular events which increase susceptibility to water loss. Seed maturity of B.flava is suggested to be polymorphic in response to an unreliable seasonal rainfall pattern.
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Caplan, M. 1993. Effect of desiccation and storage on the seeds of two related species in the Amaryllidaceae from the western Cape Province. University of Cape Town.