Pericarp anatomy and hormone profiles of cypselas in dormant and non-dormant inbred sunflower lines

Abstract

The pericarp anatomy and the effects of storage after harvest, storage temperature and early cypsela imbibition on phytohormone profiles were studied in inbred sunflower lines B123 and B91. On day 0, germination of B123 cypselas was near 0%, indicating dormancy, whereas that of B91 cypselas was near 100%, indicating non-dormancy. The germination of B123 and B91 on day 33 at room temperature (25 °C) storage was similar. Cell wall thickness and sclerification of the pericarp were higher in B123 than B91, suggesting that structural characteristics may contribute to physical dormancy in B123. Jasmonates (JAs), salicylic acid (SA) and abscisic acid (ABA) were measured in dry and imbibed pericarps. SA content of dry pericarp was higher on day 33 than day 0. SA content during imbibition on day 33 was similar for room and low (20 °C) storage temperatures. ABA content after 12 h imbibition was similar on days 0 and 33 at low temperature, but it increased on day 33 at room temperature for B123. 12-Oxophytodienoic acid (OPDA) was maximal on day 0 for B123, but peaked at day 33 at low temperature for B91. JA was higher on days 0 and 33 at room temperature as compared with low temperature. Our findings indicate that pericarp hormone profiles are affected in the two lines with different dormancy degree depending on storage conditions and imbibition processes.