Pericarp-Imposed Dormancy in Sunflower: Physiological Basis, Impact on Crop Emergence, and Removal at an Industrial Scale

DOMÍNGUEZ, CONSTANZA P.; BATTLA, DIEGO; RODRÍGUEZ M.VERÓNICA; WINDAUER, LILIANA B.; GERBALDO, MAGDALENA; BENECH-ARNOLD, ROBERTO L.

CROP SCIENCE

CROP SCIENCE SOC AMER

Lugar: Baltimore; Año: 2015 vol. 56 p. 716 - 726

0011-183X

Sunflower (Helianthus annuus L.) achenes oftendisplay pericarp-imposed dormancy, whichis long-lasting and causes serious problemsto crop production and the seed industry.For this study we assessed an extensivelyused sunflower inbred line that has this typeof dormancy. Our goals were (i) to determinethe effect of pericarp on germination and toevaluate its impact on crop field emergence, (ii)to provide insight into the physiological basis ofpericarp-imposed dormancy by determining theeffects of abscisic acid (ABA) accumulation inthe embryo and the embryo sensitivity to ABAduring incubation at different temperatures, (iii)to assess the effect of oxidant agents and othercompounds on dormancy termination, and(iv) to evaluate the feasibility of using oxidantsto remove dormancy at an industrial scale.Incubation at high temperatures (i.e., 25 to 30°C)allowed the expression of dormancy, which wasimposed by the pericarp and was accompaniedby an increase in embryo sensitivity to ABA,but not in ABA concentration. Treated acheneswith sodium hypochlorite, or their incubation inpresence of an ethylene precursor or gibberellinsovercame dormancy. ABA concentrationdecreased during incubation when treatedwith sodium hypochlorite. Application ofsodium hypochlorite on a commercial seed lot(i.e., washing with 3 and 7%, after additionalchemicals used by the industry were applied)resulted in higher germination compared withdormant non-treated controls. Field trialsshowed that pericarp-imposed dormancyreduced crop emergence in the inbred linetested herein. However, treating achenes withsodium hypochlorite using described industrialprocedures improved field emergence.