Allelopathic effect of couch grass (Elymus repens L.) on germination of common wheat seeds

The resistance of common wheat ( Triticum aestivum L.), a traditional Ukrainian crop, to allelopathic weeds in the early stages of cultivation has not been sufficiently analysed up to now. Contradictory information on the chemical interaction between wheat and couch grass ( Elymus repens L.) has led to a detailed investigation of the effect of couch grass. The aim of the experiment was to investigate the effect of the aqueous extracts of couch grass rhizomes collected in Vinnytsia region, western and south-western Ukraine on wheat seed germination and further seedling development. It was found that the presence of couch grass extracts inhibited the energy of seed germination in all experimental treatments. The couch grass extract with a concentration of 1:1000 had a stimulating effect on the germination and subsequent growth of wheat seedlings compared to the control treatment, in which the wheat seeds were germinated in the distilled water. On the 4th day of the experiment, the couch grass extracts at higher concentrations (1:100 and 1:10) significantly reduced the length of the germ root of wheat by 0.25 and 0.30 cm. On the 7th day of wheat seed germination, measurements of the stem length showed a decrease by 56.2% and 51.4% compared to the control treatment. Thus, the inhibitory effect was maybe decreasing within 5–11 days of the germination of wheat seeds depending on the concentration of allelopathically active substances of couch grass in an aqueous solution.