DORMANCY AND GERMINATION OF VELVETLEAF SEED (Abutilon theophrasti Medik.)

Cilj rada bio je utvrditi utjecaj različitih metoda na prekid dormantnosti sjemena Teofrastovog mračnjaka (Abutilon theophrasti Medik.) te utjecaj dubine sjetve sjemena na klijavost i rast klijanaca. Uz kontrolni tretman primijenjeno je tri tretmana za prekid dormantnosti sjemena: potapanje sjemena u destiliranu vodu tijekom 24 sata, potapanje sjemena u otopinu KNO3 u koncentraciji od 0,2% tijekom 24 sata, te zagrijavanje sjemena u vodi na 60 °C tijekom jednog sata. Prekid dormantnosti sjemena postignut je samo u tretmanu s vrelom vodom te je klijavost iznosila 23,8% u odnosu na kontrolu gdje je izmjerena klijavost bila 10,1%. Tretmani nisu utjecali na svježu i suhu masu te duljinu korijena klijanaca, dok je tretman s kalijevim nitratom smanjio duljinu izdanka. Sjeme mračnjaka najbolje je klijalo na dubinama od 1 do 4 cm, u prosjeku 62,7%. Nicanje se smanjivalo porastom dubine, no i četvrtina sjemena nikla je pri dubini od 9 cm. S druge strane, porastom dubine povećala se duljina klijanaca i njihova svježa masa te prosječno vrijeme nicanja.The aim of the research was to determine effects of different methods on breaking seed dormancy of velvetleaf (Abutilon theophrasti Medik.), and influence of seed's sowing depth on germination and seedling growth. Beside control treatment three more treatments were applied for breaking seed dormancy: seed immersion in distilled water for 24 hours, seed immersion in 0.2% solution of KNO3 for 24 hours and seed soaked for one hour in hot water at 60 °C. Seed dormancy of velvetleaf was broken only in treatment with hot water where germination amounted up to 23.8% as oppose to control with germination of 10.1%. Treatments had no effect on fresh and dry biomass and root length of velvetleaf seedlings, while potassium nitrate reduced shoot length. Velvetleaf seeds had better emergence percentage at sowing depths from 1 to 4 cm, in average for 62.7%. With the increase of sowing depth, the emergence of seedlings decreased, however quarter of the seeds emerged from 9 cm depth. On the other hand, with the increase of the sowing depth seedlings length and fresh weight as well as mean emergence time increased