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Dormancy, germination and seedling growth of two Kalaharian perennials of the genus Harpagophytum (Pedaliaceae)

Published online by Cambridge University Press:  10 July 2009

W. H. O. Ernst ,
T. Tietema ,
E. M. Veenendaal  and
R. Masene
W. H. O. Ernst
Affiliation:
Department of Ecology and Ecotoxicology, Biological Laboratories, Free University, Amsterdam, The Netherlands
T. Tietema
Affiliation:
National Institute for Research, University of Botswana
E. M. Veenendaal
Affiliation:
Department of Ecology and Ecotoxicology, Biological Laboratories, Free University, Amsterdam, The Netherlands National Institute for Research, University of Botswana
R. Masene
Affiliation:
National Institute for Research, University of Botswana
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Abstract

Dormancy and germination ecology of two Harpagophytum species (Pedaliaceae) from an open Acacia savanna in Botswana were investigated. The maintenance of dormancy is governed partly by the seed coat but mainly by the endosperm and the embryo itself, as demonstrated by removal of the endosperm. Dissemination of the seed from the fruit can be delayed for several years without affecting the viability of the embryo, due to very low respiration rates.

Germination can be enhanced slightly by high temperatures under natural conditions, and by gibberellic acid or removal of the endosperm under laboratory conditions. Relative growth rates for both Harpagophytum species are lower than for subtropical grasses and legumes, due to a strong investment in root and tuber biomass. Germination and seedling growth is discussed in relation to the drought avoidance syndrome and the animal disperser syndrome.

Keywords

BotswanadormancyHarpagophytumKalaharian plantsphotosynthesisseed germinationseed weightseedling survivalwater uptake
Type
Research Article
Information
Journal of Tropical Ecology , Volume 4 , Issue 2 , May 1988 , pp. 185 - 198
Copyright
Copyright © Cambridge University Press 1988

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