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The role of reproduction in <i>Glyceria maxima</i> invasion


Lutendo F Mugwedi
Jeremy Goodall
Edward TF Witkowski
Marcus J Byrne

Abstract

Glyceria maxima (Poaceae) is regarded as one of the most invasive grasses worldwide, but has only recently become naturalised in South Africa after its intentional introduction as a fodder crop in the 1940s. It invades seasonally inundated habitats. The primary reproduction mode of G. maxima within established infestations was studied at two sites in the KwaZulu-Natal Midlands. Glyceria maxima seeds were also collected from three sites (in KwaZulu-Natal) to understand their dormancy and determine viability. No seedlings were found within established G. maxima infestations. Cold stratification (4 °C) and dry storage of seeds at ambient room temperature for eight weeks did not enhance G. maxima seed germination (means: 0.5% and 2.5%, respectively). However, tetrazolium tests revealed that a high proportion of seeds that did not germinate were still viable. After-ripening of seeds for 19 months resulted in very high germination (mean: 92% across the three sites). A combination of high seed viability, physiological dormancy, high germination following after-ripening and substantial vegetative reproduction is likely to contribute to the invasion success of G. maxima in the aquatic ecosystem. Therefore, chemical control should be investigated as a matter of priority as no control recommendations for this species exist in South Africa.

Keywords: after-ripening, grass, invasive weed, propagules, wetland


Journal Identifiers


eISSN: 1727-9380
print ISSN: 1022-0119