Potential allelopathic weed species Johnsongrass (Sorghum halepense (L.) Pers.) on carrot

U ovom istraživanju proučavan je alelopatski učinak divljeg sirka (Sorghum halepense (L.) Pers.) na mrkvu, a ukupno su provedena tri pokusa: utjecaj vodenih ekstrakata divljeg sirka u Petrijevim zdjelicama, utjecaj vodenih ekstrakata divljeg sirka u posudama s tlom te utjecaj biljnih ostataka divljeg sirka u posudama s tlom. Ispitan je učinak na klijavost sjemenki mrkve, duljinu izdanka i korijena te svježu i suhu masu klijanaca. Rezultati su pokazali da divlji sirak ima značajan alelopatski učinak na mrkvu, ali se odgovor razlikuje ovisno o koncentraciji i načinu primjene ekstrakta. Općenito, veće koncentracije ekstrakata djelovale su negativno na sve ispitane biljne dijelove u Petrijevim zdjelicama dok su u posudama s tlom negativni učinci zabilježeni samo u slučaju duljine korijena i svježe mase izdanaka. Niže koncentracije djelovale su pozitivno na duljinu korijena i izdanka u Petrijevim zdjelicama te na duljinu izdanka u posudama s tlom. Povećanjem doze biljnih ostataka u posudama s tlom povećavao se i negativan utjecaj na klijavost sjemenki i svježu masu klijanaca.Possible allelopathic effects of johnsongrass (Sorghum halepense (L.) Pers.) on carrot were investigated in this research. For that purpose, three experiments were conducted: effects of water extracts of S. halepense applied in Petri dishes, effects of water extracts of S. halepense applied in pots filled with soil, and effects of plant residues applied in pots filled with soil. Effects on seed germination, shoot and root lenght were investigated as well as effects on fresh and dry weight of seedlings. The results showed that S. halepense had significant allelopathic effect on carrot, but response varied depending on extract concentration and way of its application. In general, higher concentrations applied in Petri dishes had inhibitory effect on all parts of the plants, while applied in pots with soil, inhibitory effect was recorded only in the case of root length and fresh weight of seedlings. Lower concentrations had positive effect on root and shoot length when applied in Petri dishes, and on shoot lenght when apllied in pots with soil. Increase of plant residues dose caused higher negative effect on seed germination and fresh weight of seedling