Fig. 2

Effects of relative humidity on the thermal fingerprints of Pisum sativum seeds (Experiment 1). The left panels refer to imbibition of pea seeds at a target RH of 30% (termed "30% RH") and the right panels refer to imbibition at RH close to 100% ("100% RH"). In both cases, seeds were wetted from below with liquid water. a, e Seed moisture content (MC) of "live" (green line) seeds that germinated and "dead" (red line) seeds that did not germinate. Data show means ± SE (n = 10 "dead" seeds; n = 20 "live" seeds). Asterisks above the symbols denote significant differences in MC between "live" and "dead" seeds (P < 0.05; Mann–Whitney U test). b, f Thermal fingerprints of "live" and "dead" seeds, showing median values of relative temperature (rT) during imbibition. Arrows indicate interruptions between IR measurements during the weighing of seeds that were temporary taken out of the chamber for MC assessment (see “Methods”). c, g Differences between the fingerprints of "live" and "dead" seeds. Horizontal green bars indicate the time windows in which the T values of "live" seeds differed significantly from that of "dead" ones (P < 0.05; Two Sample t-test). d, h Relative humidity (RH) surrounding the seeds during the thermal recording. Open blue horizontal bars indicate the time periods of hydration by water vapour and closed blue bars indicate imbibition in liquid water from below