Dormancy and germination of johnsongrass seed (Sorghum halepense (L.) Pers.)

Cilj istraživanja bio je utvrditi učinkovitost različitih metoda prekida dormantnosti sjemena sirka (Sorghum halepense (L.) Pers.) odnosno njihov utjecaj na klijavost i rast klijanaca. Uz kontrolni tretman primijenjeno je osam tretmana za prekidanje dormantnosti sjemena: potapanje sjemena u destiliranu vodu, zagrijavanje u vodi na 60 °C, potapanje u 0,2% otopinu KNO3, te 2% otopinu NaOCl, tretiranje koncentriranom H2SO4 tijekom 5 i 10 min, te tijekom 5 min i naklijavanje u tami, te kombinirani tretman sumporne kiseline (5 min) i 1,5% otopine KNO3. Sjeme divljeg sirka u kontrolnom tretmanu imalo je vrlo nisku klijavost, svega 2,8%. Svi tretmani povećali su klijavost sjemena, a najviša klijavost zabilježena je tretmanu s kombinacijom H2SO4 i KNO3 (35,0%) te tretmanu s 2% otopinom NaOCl (30,6%). Primjena NaOCl smanjila je duljinu korijena klijanaca divljeg sirka za 40,9% u odnosu na kontrolu, dok su svi tretmani imali pozitivan utjecaj na duljinu izdanka. Ukupna duljina klijanaca bila je najviša pri tretiranju sjemena sumpornom kiselinom tijekom 5 minuta. S druge strane, tretmani nisu pokazali značajan utjecaj na svježu masu klijanaca divljeg sirka. Najbrže je klijalo sjeme u tretmanu s kombinacijom H2SO4 i KNO3 (4,58 dana), a najsporije kod potapanja sjemena u vodu (8,16 dana) te u 2% otopinu NaOCl (8,92 dana).The aim of this study was to determine the effectiveness of various methods on breaking seed dormancy of johnsongrass (Sorghum halepense (L.) Pers.) and their influence on germination and seedlings growth. Beside control treatment, eight treatments for breaking dormancy of seeds were applied: seeds immersion in water, seed heating in water at 60 °C, immersion in a 0.2% solution of KNO3, and 2% solution of sodium hypochlorite, treatments with concentrated H2SO4 for 5 and 10 minutes, and for 5 min and germination in darkness, and the combined treatment of sulphuric acid (5 min) and 1.5% KNO3 solution. Seeds of johnsongrass had very low germination percentage in the control treatment, only 2.8%. All treatments increased the germination of seeds, and the highest germination was observed in treatment with combination of H2SO4 and KNO3 (35.0%) and treatment with 2% NaOCl (30.6%). NaOCl reduced the root length of seedlings for 40.9% compared to control, while all treatments had a positive effect on the shoot length. Total seedlings length was the highest when seeds were treated for 5 minutes with sulphuric acid. On the other hand, none of the treatments showed significant effect on johnsongrass seedlings fresh weight. Seed germinated fastest in treatment with a combination of H2SO4 and KNO3 (4.58 days), and slowest when seeds were immersed in water (8.16 days) and in the 2% solution of NaOCl (8.92 days)