Allelopathic Effects Produced by Johnson Grass Extracts over Germination and Growth of Crop Plants

Abstract

The paper addresses a topic justified by economic importance due to direct and indirect damages caused by Johnson grass in maize and soy culture. The study aimed to highlight the allelopathic effects produced by Johnson grass extracts on seed germination, plant height and plant dry mass of corn and soybeans. The research was conducted in the laboratories of Agrochemistry and Plant Protection Department in University of Agricultural Sciences and Veterinary Medicine of Banat. Experimental field has 13 variants, which are different throughout plant material used (rhizomes dry, fresh, leaves, and seeds) as well as various alcohol concentrations. Following the treatments application with extracts we observed that the highest allelopathic effect is determined by extracts based on rhizome, second being situated leaf extract. The aqueous extracts were less inhibitory compared with the alcoholic extracts. Lowest content of alkaloids that cause allelopathic effect is recorded in seeds. The experiment showed that the seed germination percentage of inhibition depended on the time used and the concentrations of the plant material used (rhizomes, leaves, seeds)