Headspace Floral Volatiles Analysis

The collection of headspace floral volatiles and GC–MS analysis were carried out as previously described (Yue et al., 2014 (link); Ke et al., 2021 (link)). In short, entire flowers from each stage were placed in a 500 mL glass bottle, and 1.728 μg (microgram) ethyl caprate was added as an internal standard. The glass bottle was stilled for 30 min, and then a polydimethylsiloxane (50/30 μm divinylbenzene/carboxen) fiber (Supelco) was injected into the glass bottle to trap volatiles for 30 min. Thereafter, the adsorbed volatile compounds were analyzed using a GC–MS system with an Agilent 7890A GC and Agilent 5975C MSD as previously explained (Yue et al., 2015 (link), 2021 (link)).