Contribution to the Ecology of Dactyloctenium aegyptium (L.) P. Beauv.

Abstract

Dactyloctenium aegyptium, which is a nutritious fodder, grows abundantly in the campus of University of Ibadan, Nigeria, under tropical climate and supported by reddish-brown loamy soil. The species shows morphological variations and three forms have been recognized. Form A is small sized, Form B medium, while Form C is large. Each form grows with different associated species, though some of them are common to all forms. The three forms behaved differently with respect to germination requirements, biotic disturbance, and water stress. Cultural experiments revealed germination lower on filter paper than on soil, a progressive decrease in germination with depth, no germination at 4 cm and 5 cm depths, and a general increase in germination from 10 degrees C to 25 degrees C. Form C did not germinate at all in total darkness but had the highest germination in glass-house and it was the only one that germinated in continuous light. Most of the results of various germination experiments showed that Form A had the least germination, followed by Form B, while Form C had the highest germination. Experiments on water stress revealed that Form B showed the best growth but it was only Form C that had flowered. There are persistent differences in three Forms with regard to growth habit, period of maturity, spike coloration, and germination behavior, which indicate that they are likely to be ecotypes.