Allelopathic effect of johnsongrass (Sorghum halepense (L.) Pers.) on germination and growth of sugar beet

Cilj istraživanja bio je utvrditi alelopatski utjecaj divljeg sirka (Sorghum halepense (L.) Pers.) na klijavost sjemena i rast klijanaca šećerne repe. Provedena su dva pokusa: utjecaj vodenih ekstrakata od različitih biljnih dijelova divljeg sirka u Petrijevim zdjelicama, te utjecaj biljnih ostataka nadzemne mase divljeg sirka u posudama s tlom. Istražen je utjecaj na klijavost / nicanje šećerne repe, duljinu izdanka i korijena te svježu i suhu masu klijanaca. Rezultati su pokazali da divlji sirak ima značajan pozitivni i negativni alelopatski utjecaj na šećernu repu. U pokusima u Petrijevim zdjelicama najveći inhibitorni učinak zabilježen je u tretmanima s najvišom koncentracijom ekstrakata (10%), posebice ekstrakta korijena divljeg sirka. Biljni ostatci divljeg sirka nisu djelovali na nicanje sjemena, dok su veće doze (20 i 30 g/kg tla) smanjile duljinu izdanka te svježu i suhu masu klijanaca šećerne repe.The aim of the study was to determine the allelopathic effect of johnsongrass (Sorghum halepense (L.) Pers.) on seed germination and seedling growth of sugar beet. Two experiments were carried out: the effect of water extracts from various johnsongrass plant parts in Petri dishes, and the influence of johnsongrass aboveground plant residues in pots with soil. The influence on germination / emergence of sugar beet seeds, length of seedling root and shoot, and fresh and dry weight of seedlings was studied. The results showed that johnsongrass has a significant positive and negative allelopathic effect on sugar beet. In the Petri dish experiment, the highest inhibitory effect was observed in treatments with the highest extract concentrations (10%), in particular with johnsongrass root extract. Johnsoongrass plant residues did not affect seed emergence, while larger doses (20 and 30 g per kg soil) reduced the length of the shoot and the fresh and dry weight of sugar beet seedlings