Allelopathic influence of dominant weeds of North-Western Himalayan region on common cereal crops

A study on the allelopathic potential of Ageratum conyzoides and Eupatorium adenophorum two dominant weeds of North-Western Himalayan region on three common cereals viz., Triticum aestivum cv. HPW-42 (wheat), Oryza sativa cv. Hasanshrai basmati (paddy) and Zea mays cv. Girija (maize) revealed significant inhibition of seed germination. Lower concentration of E. adenophorum macerated aqueous extract showed stimulatory effect on plumule growth in wheat and maize seedlings while all other treatments led to inhibition of plumule length. Likewise, the radicle length was significantly more in case of maize seedlings on exposure to E. adenophorum macerated aqueous extract (50 per cent) than that of control. All other treatments caused significant reduction in the radicle growth. The inhibitory effect was much pronounced for radicle growth as compared to the plumule growth for all the treatments except E. adenophorum macerated aqueous extract (50 per cent). There was a significant reduction in seed vigor index in case of all the treatments except E. adenophorum macerated aqueous extract (50 per cent). Among the test crops, maize with larger seeds was least sensitive to the application of various extracts/fractions while wheat and paddy with small seeds were more susceptible to the allelopathic effect of both weeds. The results of the study could be important in planning the area under different crops in view of the prevalent agro-ecosystem for better outputs.