A low-temperature requirement for dormancy break has been observed frequently in temperate-climate Apiaceae species, resulting in spring emergence of seedlings. A series of experiments was performed to identify dormancy-breaking requirements of Aegopodium podagraria, a nitrophilous perennial growing mainly in mildly shaded places. In natural conditions, the embryos in seeds of A. podagraria grow in early winter. Seedlings were first observed in early spring and seedling emergence peaked in March and April. Experiments using temperature-controlled incubators revealed that embryos in seeds of A. podagraria grow only at low temperatures (5°C), irrespective of a pretreatment at higher temperatures. Seeds did not germinate immediately after embryo growth was completed, instead an additional cold stratification period was required to break dormancy completely. Once dormancy was broken, seeds germinated at a range of temperatures. Addition of gibberellic acid (GA3) had a positive effect on embryo growth in seeds incubated at 10°C and at 23°C, but it did not promote germination. Since seeds of A. podagraria have a low-temperature requirement for embryo growth and require an additional chilling period after completion of embryo growth, they exhibit characteristics of deep complex morphophysiological dormancy.

The physically dormant seeds of Ipomoea lacunosa and of I. hederacea undergo sensitivity cycling (insensitive ↔  sensitive) to dormancy-breaking treatment. Sensitivity cycling is important to seeds with physical dormancy in sensing appropriate environmental conditions for germination. Seed vigour is also important to seedling establishment, but no study has compared changes in vigour (or not) with changes in sensitivity. This study was conducted to determine the relationship between sensitivity cycling and seed vigour in I. lacunosa and I. hederacea. The seed moisture contents of insensitive and sensitive seeds of I. lacunosa and of sensitive seeds of I. hederacea were measured, and several vigour tests were performed. Vigour of sensitive seeds of I. lacunosa decreased more rapidly than that of insensitive seeds. No significant change in vigour was observed in either permeable or impermeable seeds of I. hederacea. We conclude that sensitivity cycling to physical dormancy break is important in maintaining vigour of I. lacunosa seeds in the soil seed-bank.

Evidence for effects of saprophytic fungi on buried seed demography is usually obtained from studies involving the simultaneous burial of fungicide-treated seeds and of untreated seeds. However, any potential influence of fungicide treatment on seed dormancy levels is generally ignored in these studies. Also, some studies assume that a combination of several fungicidal compounds provides better protection against a broader range of fungi, ignoring chemical interactions that may potentially occur between different compounds. To investigate these issues, we carried out a 6-month burial experiment using seeds of Anthriscus sylvestris (L.) Hoffm., Centaurea nigra L. and Daucus carota L., and three substrates differing in organic matter content. Three fungicidal compounds, captan, iprodione and mancozeb, were applied alone and in combination, including an untreated control. All fungicidal compounds and combinations thereof provided protection against fungal-induced seed mortality and, except for a low efficacy of iprodione in protecting seeds of Anthriscus, there were no pronounced differences in seed mortality between different fungicide treatments. Captan temporarily inhibited germination in Centaurea, whereas a similar inhibition in Daucus seeds caused by mancozeb was more long lasting, suggesting an induction of secondary dormancy. Organic matter content had only a negligible influence on these results. Our results suggest that the basic conclusions from most seed burial studies are robust with respect to their choice of fungicide. We conclude by discussing further implications of our findings for the design and interpretation of seed burial studies.

The purpose of our study was to better understand seed germination ecology of the spring ephemeral herbaceous perennials, Ixiolirion tataricum, Tulipa iliensis and Scorzonera pusilla, in the temperate desert in the Junggar Basin of northwestern China. Seeds of I. tataricum, T. iliensis and S. pusilla were dormant at maturity but when subjected to cold, dry (2 months at 4°C) followed by cold, wet ( ≤ 40 days at 4°C) conditions, they germinated to 100%, 96% and 93%, respectively. After 2 months' dry storage at 4°C, seeds germinated to only 11%, 3% and 42%, respectively at 15°C, and no seeds germinated at 30°C. Seeds of the three species were not sensitive to light. Low ( < 12.7%) and high (21.4%) soil moisture contents suppressed germination. In addition, both final germination percentages and rates of the three species decreased dramatically with a decrease in water potential from 0 to − 3.17 MPa. Thus, the low-temperature requirement for dormancy break and germination cues seed germination to occur in early spring when soil moisture is favourable for germination and subsequent seedling establishment.

Seeds of the iconic Australian baobab Adansonia gregorii display physical dormancy (PY) and germinate readily once they become water permeable, a trait found in most other species in this genus. Highest germination (100%) was observed when seeds were placed in concentrated sulphuric acid (H2SO4) for 24 h, although exposure to H2SO4 for 6–12 h also resulted in >85% germination. Exposure to boiling water for 1–5 min was far less effective in promoting germination (0–23%), although a high number of seeds were water permeable (67–99%) following boiling water treatment. However, the majority of these water-permeable seeds appeared to have been injured by boiling water exposure. Germination at warmer temperatures (30 or 35°C) was found to be optimal (81–83% germination) and proceeded rapidly, with maximum germination occurring after incubation for only 8 d. In comparison, germination at 15–25°C resulted in 3–67% germination over a longer time frame (up to 20 d). While seeds of A. gregorii display PY they are unusually sensitive to dipping in boiling water and are therefore atypical when compared to most other Adansonia species.