Allelopathic effect of weed species Johnsongrass (Sorghum halepense (L.) Pers.) on lettuce

Cilj istraživanja bio je utvrditi alelopatski utjecaj vodenih ekstrakata divljeg sirka (Sorghum halepense (L.) Pers.) na rast i razvoj salate. Provedena su 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 uĉinak na klijavost sjemenki salate, duljinu izdanka i korijena te svježu i suhu masu klijanaca. Rezultati su pokazali da divlji sirak ima znaĉajan alelopatski uĉinak na salatu. U pravilu, veće koncentracije imale su najveći inhibitorni utjecaj, dok su s druge strane, u pokusu s posudama s tlom, niže koncentracije djelovale pozitivno na svježu i suhu masu klijanaca. Biljni ostatci divljeg sirka znaĉajno su negativno utjecali na nicanje i rast klijanaca u obje ispitivane doze od 10 i 20 g po kg tla.The aim of this study was to determine allelopathic effect of water extracts of johnsongrass (Sorghum halepense (L.) Pers.) on the growth and development of lettuce. Three experiments were conducted: effect of water extracts of S. halepense in Petri dishes, effect of water extracts of S. halepense in pots with soil and effect of plant residues applied in pots with soil. Effect on seed germination, shoot and root lenght were investigated as well as effect on fresh and dry weight of seedlings. The results showed that S. halepense had significant allelopathic effect on lettuce. Generally, higher concentrations had the highest inhibitory effect, and on the other hand, in experiment in pots with soil, the lower concentrations had positive effect on fresh and dry weight of seedlings. Plant residues of S. halepense had significantly negative influence on the emergence and growth of seedlings in both studied doses of 10 and 20 g per kg of soil