Volume No. 6 Issue No.: 4 Page No.: 953-963 April-June 2012

 

REPRODUCTIVE ECOLOGY OF A Pennisitum dichotomum VERSUS ITS INVASIVE COMPETITOR Pennisetum setaceum

 

Chiraz Chaffei Haouari*, Afef Hajjaji Nasraoui, Ali Haouari and Houda Gouia

Département De Biologie, Faculté des Sciences de Tunis, Campus universitaire El Manar I,Tunis (TUNISIE)

 

Received on : March 10, 2012

 

ABSTRACT

 

We compared the reproductive biology of a native grass, Pennisetum dichotomum, and its invasive alien competitor, Pennisetum setaceum, to identify differences that could explain why the alien has spread so successfully while the native has declined. Both species are drought tolerant. In a series of experiments, we compared the phenology, ovule production, seed production, and seed germination in P. dichotomum and P. setaceum. The alien produced two to nine times more seeds per plant than the native. Furthermore, the germination rate for fresh seeds was significantly greater for P. setaceum (47%) than for P. dichotomum (14%). In experiments, clipping, burning, and pollen addition did not affect final reproductive rate in either species. However, P. setaceum recovered from clipping and burning more rapidly both in terms of vegetative growth and flowering, which likely gives it an advantage in disturbed environments and in competition with P. dichotomum. P. setaceum plants failed to produce seeds in low water and low nutrient treatments. In contrast, P. dichotomum flowered and produced seeds in all treatments, indicating better tolerance of low resources.

 

Keywords : Pennisitum dichotomum, Pennisetum setaceum, Reproduction, Phenology, Seed Production

 

 

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