Allelopathic effect of two medicinal plants on seed germination, seedling growth and grain production of purslane (Portulaca oleraceae L.) weed

A laboratory factorial (2 × 5) experiment was carried out based on completely randomized block in four replications to evaluate the effect of plant species and concentration of their allelopathic extracts on seed germination and seedling growth of purslane weed (Portulaca oleraceae L.). The first factor studied was plant species (Artemisia sieberi and Salvia syriaca) and the second one the concentration percentage of plant ethanol extract (0.0, 5 %, 10 %, 15 % and 20 %). The effect of Artemisia on germination reduction of purslane was stronger compared to Salvia. The results indicated that higher extract concentration led to decreased germination percentage, germination speed and seedling growth indices of purslane including leaf length, leaf number, leaf width, leaf dry mass, stem mass and stem length. The effect of Artemisia was higher than that of Salvia. In a complementary experiment, the effect plant residues of Artemisia and Salvia (0.0, 1, 2, 3 and 4 g kg-1 soil) were evaluated in a factorial experiment base on completely randomized block design with three replications. The results of field experiment showed that plant residues significantly (P ≤ 0.01) reduced capsule number per plant, seed number per capsule, seed production and shoot dry mass, while its effect on 1000-seed mass was not substantial. The effect of plant species and the interaction of plant species and their allelopathic extracts concentration had no major impact on the above-mentioned properties. The increase in plant residues in soil, led to the reduction of growth and seed production of purslane induced by plant number per unit area and capsule per plant. Artemisia sieberi Bess. and Salvia syriaca L. residues can be successfully used for non-chemical control of purslane weed.