ALLELOPATHIC POTENTIAL OF CYPERUS ROTUNDUS L. AND CYNODAN DACTYLON L. ON GERMINATION AND GROWTH RESPONSES OF SOME RICE CULTIVARS

Abstract

Weeds are enemies to the crop plants and have harmful effects on agricultural crops due to several factors such as competition for space, light and nutrients and allelopathy. In the present study,various concentrations (0,5,10,15,20 and 25%) of whole plant aqueous extractsof weeds, Cyperus rotundusL.( Purple nut sedge) and Cynodan dactylon(L.) Pers. (Bermuda grass) were tested for assessing their allelopathic potential on seed germination and seedling growth of some rice (Oryza sativa L.) cultivars i.e.ADT-36,BPT5204 and IR-20 using pot culture experiments. The experimental results revealed that all the concentrations of both the weed extracts had inhibition on germination percentage, seedling length, number of,dry weight and chlorophyll contents of 15 day old seedlings of all the three rice cultivars and the inhibitory effect of the extracts was concentration dependent. However, at 5% of C. rotundus and10% of C. dactylon extracts did notaffect seed germination of IR-20 . Among the rice cultivars,the higher degree of growth inhibition was observed in ADT-36followed by BPT-5204 and IR-20 . The weed C.rotundusexhibited more intense on growth suppression of rice cultivars thanC.dactylon.