Morphological Characterization And Population Dynamics Of Cyperus Rotundus L. In Vegetable Fields Of Southern Ghana

ABSTRACT

Vegetable production in southern Ghana suffers grave setbacks from purple

nutsedge infestation. Several attempts to identify effective and

environmentally friendly management methods using the traditional weed

research methods have so far not been successful. Hence, this study aimed at

designing efficient and environmentally sound management methods by

developing an ecological model of the population dynamics of purple nutsedge

in vegetable fields. The study comprised three major phases: survey of the

agronomic practices and prevalence of the weed in the four agro-ecological

zones in the study area, morphological characterization of the weed and the

development of an ecological model which was used in determining an

appropriate management method. Purple nutsedge was reportedly present on

the fields of more than 50 per cent of farmers interviewed and was said to be a

problem all year round, especially in the wet season. The weed showed some

level of morphological adaptation to agro-ecological conditions in the study

area. The major factors which determined differences in purple nutsedge were

photosynthetic structures (involucral bracts and leaves), plant height and leaf

characteristics. On the whole, differences observed in the morphology of the

weed were independent of the agro-ecological zones, despite the adaptations

observed. The ecological model reflected purple nutsedge population

dynamics at weekly intervals and the yield loss in cabbage (as a test crop) and

hence was used to investigate various management options for the weed. It

was clear that only an integrated weed management approach could effectively

manage purple nutsedge. This approach should include an effective means of

reducing the initial viable tuber density of the purple nutsedge.