Germinated Tillandsia usneoides pollen.
Subject: Pollen (Management)
Moss (Care and treatment)
Germination (Methods)
Author: Dorris, Michael
Pub Date: 09/01/2010
Publication: Name: Journal of the Bromeliad Society Publisher: Bromeliad Society International Audience: Academic Format: Magazine/Journal Subject: Biological sciences Copyright: COPYRIGHT 2010 Bromeliad Society International ISSN: 0090-8738
Issue: Date: Sept-Oct, 2010 Source Volume: 60 Source Issue: 5
Topic: Event Code: 200 Management dynamics Computer Subject: Company business management
Geographic: Geographic Scope: United States Geographic Code: 1USA United States
Accession Number: 257434812
Full Text: Pollen is the male non-flagellated, gametophytic cell found in most vascular plants from Cycads to palms; the spore producing ferns and lycophytes are a bit different. Pollen carries half the genetic compliment to the prospective zygote but without the plastid component (chloroplasts and other chromoplasts) of the female ova so it contributes just a bit less or contributes differently than the ova.

In the plant breeding process it is often useful to verify the quality of the pollen used, this is done by germinating the pollen; a varitey of formulas can be used including pure water. For germinating Tillandsia usneoides pollen I used the Kwack (1965) formulation because it works well with a number of plants. 10% sucrose, 100 PPM boric acid, 300 PPM Ca(No3)2, 200 PPM Mg SO4, 100 PPM KNO3 in distilled water, Ph to 7.3.

Sometimes 20% sugar is used to balance the presumed higher osmotic pressure of the inner walls of the pistil surface, but Kwack (1965) with 10% sugar works well.

The drawback is this test only shows if the pollen can germinate and as microbes grow on it just as well as pollen an overall figure of the percentage germinated is not accurate as in nature pollen can take days to reach its goal and pollen tube formation is far from synchronous. Microscopic studies (De Proft, 2002) have shown later pollen tubes can take advantage of earlier tubes; physically as it allows a "path" and chemically as the earlier tubes mask the pollen's chemical signature, allowing less compatible pollen to sneak past the pistol's defences; hence the basis for "mentor pollen" i.e. mixing compatible and less compatible pollen together.

Illustrations (opposite)

Tillandsia usneoides, germinating pollen after 5 hours at 28OC, scale in microns. Photos by Michael Dorris .

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Literature Cited

de Proft, M. P., Ed. (2002). Functional anatomical study of the fertilization in Bromeliaceae: Dissertations de Agriculture. Leuven, Katholieke Universiteit.

Kwack, B. H. (1965). "The effects of calcium on pollen germination." P AM SOC HORTIC SC 86: 818-823.
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