Fig. 5 Seed survival in the soil; (a) Probability of finding seeds in 2021 that were sown in 2019 and 2020 according to burial-depth and accession; (b) viability of seeds found in 2021 using a germination test in an incubator (IN) and the tetrazolium chloride test (TTC), with reference to viability at the start of the experiment using embryo rescue techniques (ER), and maximum germination achieved in a Simulated-NH; p values show contrasts (Dunnett test) against original viability (ER) for each year.
Seeds that were removed from storage and incubated under suitable conditions (20/35°C), displayed dormancy i.e., they did not germinate at all. However, if they were buried in the soil at 7 cm for up to three months, germination significantly increased to probability 0.4 (t=2.518, p=0.021, Fig. 6).