Productivity and Plasticity of Wheat and Cynodon dactylon (L.) Pers. in Pure and Mixed Stands

During the growth of an individual crop plant, its development may be modified by the proximity of others. This modification may be due to intraspecific or interspecific competition. Whilst a number of studies to determine the influence of density on plasticity of plants are known (Clements, Weaver & Hanson 1929; Hodgson & Blackman 1956, 1957; Eddowes 1969a, b), little has been done to determine crop-weed interference with reference to the response of the weed species (Harper & Gajic 1961). Further, competition that is keenest between species that are most similar (Harper & McNaughton, 1962; Black 1960; de Wit 1960; Cowling & Lockyer, 1968) or between ecotypes within species (Snaydon 1962; Ramakrishnan 1965, 1970) has received relatively more attention. Hence it was proposed to determine the effect upon one another due to interference between a weed and a crop, especially when the size and growth habit of the competing species are quite dissimilar. Cynodon dactylon (L.) Pers. is a serious weed throughout India all through the year and exhibits a wide ecological tolerance. This is due to its great plasticity under different situations as shown by the present study, the presence of ecological races suited to specific habitat conditions (Ramakrishnan & Singh 1966) and the very effective vegetative spread by runners in addition to seed production. The present study deals with the behaviour of C. dactylon and wheat when grown in pure and mixed cultures at different densities and proportions.