Ecophysiology of the Selective Association between Weeds and Weed and Crops

Summary Digera alternifolia Aschers, is one of the common weeds of crop fields. It is observed that this weed is associated with certain crops only and remain absent from the fields of the other crops. So also, it fails to form association with other commonly invading weeds of the area. A possible cause of this selective association was sought. It appears that the root exudates of the crops play important role in such a distribution and association. The role of the inhibiting substances present in this weed becomes important as it can hamper the germination of the seeds of the other common weeds. We can conclude therefore that the association of plants may depend upon the substances produced in plant body and their retainment in side the body or release in the environment.