Allelopathic Effect of Dodder on Different Varieties of Lucerne and Bird’s Foot-Trefoil

The aim of this study was to evaluate the allelopathic effect of cold aqueous extracts, both fresh and dry biomass of dodder (Cuscuta epithymum L.) on lucerne (Medicago sativa L.) and bird’s foot-trefoil (Lotus corniculatus L.). Four different varieties of lucerne “Pleven 6”, “Dara”, “Roly”, “Multifoliolate”) and bird’s foot-trefoil (“Gran San Gabriele”, “Leo”, “Local population 1”, “Local population 2”) were studied in order to find some varieties with allelopathic tolerance. Ex-situ experiment was carried out as follows: 100 seeds of each variety were put in Petri dishes between filter paper, both cold extracts of parasitic weed biomass were pipetted at a ratio of 1:20 as against the seed mass and then were placed in a thermostat-operated device at a temperature of 22 ± 2°С. Distilled water was used as a control. Percentage inhibition, Index of tolerance and Index of plant development were calculated for assessment of the allelopathic effect of dodder on the early seedling growth, biomass synthesis and initial development of experimental varieties. As a whole, dry weed biomass was found as more toxic for the tested plants than the fresh one. Medicago sativa var. multifoliolate and Lotus corniculatus var. Local population 1 and Local population 2 showed a significant tolerance to the allelopathic influence of Cuscuta epithymum in all studied concentrations of aqueous extract of fresh weed biomass (25, 50 and 100 g l⁻¹) and medium tolerance to aqueous extract of dry weed biomass (concentrations of 25 and 50 g l⁻¹).