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

Cilj istraživanja bio je utvrditi alelopatski utjecaj nadzemne suhe mase divljeg sirka (Sorghum halepense (L.) Pers) na klijavost sjemena i rast klijanaca kelja. Ukupno su provedena tri pokusa: utjecaj vodenih ekstrakata divljeg sirka u Petrijevim zdjelicama, utjecaj vodenih ekstrakata divljeg sirka u posudama s tlom i utjecaj biljnih ostataka divljeg sirka u posudama s tlom. Istražen je utjecaj na klijavost sjemena kelja, duljinu korijena i izdanaka te svježu i suhu masu klijanaca. Rezultati su pokazali da divlji sirak ima značajan alelopatski utjecaj na kelj. Pokusi provedeni u Petrijevim zdjelicama imali su najveći utjecaj, gdje je kod većih koncentracija ekstrakta zabilježen veći negativni utjecaj na klijanje sjemena i rast klijanaca. U posudama s tlom ekstrakti nisu pokazali značajan alelopatski utjecaj. Biljni ostaci divljeg sirka u obje ispitane doze od 10 g i 20 g po kg tla pokazali su značajan inhibitorni utjecaj na nicanje sjemena, ali pozitivno djelovanje na svježu i suhu masu klijanaca.The aim of this study was to determine allelopathic effect of johnsongrass (Sorghum halepense (L.) Pers.) aboveground dry biomass on seed germination and seedlings growth of kale. Three experiments were contucted: the effect of water extract of johnsongrass in Petri dishes, the effect od water extract of johnsongrass in pots with soil and the effect of plant residues of johnsongrass in pots with soil. Effect on seed germination, shoot and root length were investigated as well as the effect on fresh and dry weight of seedlings. The results showed that johnsongrass had significant allelophatic effect on kale. Water extracts applied in Petri dishes had the greatest effect, with the gratear concentration of the extract having a greater negative impact on seed germination and growth of seedlings. In pots with soil, was no significant allelophatic effect noticed. Johnsongrass plant residues applied in both doses of 10 g and 20 g per kg of soil showed a significant ingibitory effect on the emergence of seedlings, however positive effect was recorded on fresh and dry weight of seedlings