ISSN: 1659-2751

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Seed Storage of Different Orchid Species for Conservation in a Germplasm Bank: II. Dehydration, Storage and Viability Tests of the Seeds

Abstract

The storage of seeds represents a potential as an ex situ conservation for endangered neotropical orchid species. The objective of this study was to evaluate different short-term storage conditions of orchid seeds to extend their viability, at the Natural Sciences Laboratory, EARTH University. The efficiency of LiCl was compared with that of CaCl2 as desiccants to increase the longevity of seeds at -20 °C, 5 °C, 25 °C and 60 °C. Two types of storage envelopes were evaluated: waxed paper envelopes and glass vials. Different viability tests mentioned in the literature were evaluated including a pretreatment with Ca(OCl)2, an additional treatment with malachite green and a seed test to see if they float. Dehydration with both desiccants, LiCl and CaCl2, was recommended for storage at -20 °C and 5 °C for the first and 5 °C for the second. Seeds stored in glass vials preserved their viability longest. Pretreatment with Ca(OCl)2 affected the species tested, significantly reducing their viability. The same results were obtained in the tests with tetrazolium with or without the malachite green. Both methods are valid; however, it was not necessary to stain with malachite green in order to be able to identify the embryos. The precision of the results are influenced by the ability of the analyst to interpret the information. The ability of the seeds to float or not was not a good indicator of the percentage of viability or of embryos.

Key words: Storage, orchids, seeds, tetrazolium, malachite green, viability.

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