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Heretofore, no detailed account was available on seed dormancy and germination of a member of the Colchicaceae (Liliales). Thus, the primary aim of this study was to do an in-depth investigation of the temperature requirements for dormancy break and germination in seeds ofMerendera montana(Colchicaceae) at the embryo and whole-seed levels under near-natural temperatures in a non-heated frame shade-house and under controlled conditions in the laboratory. Mean embryo length in fresh seeds wasc. 0.57 mm and embryos had to grow to at least 1.30 mm before radicle emergence. Embryos grew to full size and seeds completed germination (radicles emerged) when they were stratified at 28/14°C for 60 d followed by a cool temperature for 60 d and then incubated at a cool temperature for 30 d. The optimum cool stratification temperature for dormancy-break was 10°C. Thus, after the moist pretreatment at 28/14°C+10°C, radicle emergence was>93% at all incubation temperatures (5, 15/4 and 20/7°C). In its natural habitat,M. montanaseeds are dispersed in June, the embryo elongates to full size in autumn and radicles emerge from early November to early February. Although the shoot does not emerge until March and April, it is not physiologically dormant. The shoot emerged from 80% of the radicle-emerged seeds in 13 d at 20/7°C without a previous cold pretreatment. Seeds ofM. montanahave non-deep complex morphophysiological dormancy, C1b1aB-C1a. This is the first study on seeds with complex MPD to show a delay in shoot emergence following root emergence despite the shoot being physiologically non-dormant.

Seeds of Aconitum napellus subsp. castellanum were physiologically dormant at maturity in early autumn, with underdeveloped embryos. Thus they have morphophysiological dormancy (MPD). Embryos in fresh seeds were on average 1.01 mm long, and they had to grow to 3.60 mm before radicle emergence. Cold stratification at 5°C for 5 months with light enhanced the mean embryo length to 2.73 mm (SE = 0.13) and seed germination to 20%. However, with higher temperatures (15/4, 20/7, 25/10, 28/14 and 32/18°C) embryo growth was small, with no seeds germinating. Optimal germination was achieved after 4 months of cold stratification at 5°C followed by incubation at 20/7°C for 1 month with light, when germination ranged between 70 and 79%, depending on seed age, locality and year of collection. Cold stratification could be substituted by the application of GA3 solution, since mean embryo length in seeds incubated at 25/10°C for 1 month with light was 3.52 mm and the germination was 80%. Since cold stratification was the only requirement for the loss of MPD, the longest embryo growth occurred during this treatment, and GA3 promoted MPD loss, we concluded that A. napellus seeds have intermediate complex MPD. Germination was higher in 4-month stored than in freshly matured seeds. A pronounced variability in germinative patterns at inter-annual and inter-population level was recorded.

Narcissus longispathus(Amaryllidaceae) is a perennial geophyte and a Mediterranean narrowly endemic species. At dispersal time,N. longispathusseeds are dormant and have underdeveloped embryos. This work aimed to determine requirements for dormancy break and germination and to compare dormancy traits with those of the two endemic Iberian congeners. Phenology of embryo growth and germination were studied by regularly exhuming seeds sown in near-natural conditions. Temperature and light requirements for embryo growth, breaking of dormancy and germination were determined by incubating seeds under controlled laboratory conditions. Mean embryo length in fresh seeds was 1.50 mm, and embryos had to grow to 3.80 mm before radicle emergence. Embryos grew to full size and seeds germinated when they were warm stratified for 2 months (optimum 1 month at 20/7°C+1 month at 15/4°C), then cold stratified at 5°C for 2 months, and finally incubated at cool temperatures (15/4°C) for 30 d. However, in seeds only subjected to either warm or cold stratification, the embryos hardly grew and did not germinate. In natural conditions, the embryos elongate in autumn–winter, and in late winter–early spring (March) almost all radicles and seedlings emerged. Velocity of embryo growth and germination percentages increased with seed storage duration. Seeds ofN. longispathushave non-deep complex morphophysiological dormancy (MPD). This is the first report of such a level of MPD inNarcissus. Our data suggest that non-deep complex MPD may have been derived from intermediate complex MPD in the sectionPseudonarcissi.

The germination ecology of the winter annual Iberian endemicsIberis pectinataandZiziphora aragonensiswas investigated in order to better understand adaptations of rare species to their natural habitat and to improveex-situpropagation techniques and management of their habitat. Specifically, we analysed the following aspects: (1) influence of temperature, light conditions and seed age on germination patterns; (2) phenology of germination; (3) germinative response of buried seeds to seasonal temperature changes; and (4) temperature requirements for induction and breaking of secondary dormancy. Germination was substantially lower in darkness than with a photoperiod in both taxa, with this difference being more pronounced inZ. aragonensis. Freshly matured seeds showed conditional physiological dormancy, germinating at low and medium temperatures but not at high temperatures (28/14 and 32/18°C). Germination capability increased with time of dry storage in both species, suggesting the existence of non-deep physiological dormancy. Under greenhouse conditions, germination of both taxa was mostly concentrated in autumn (October–November), while spring percentages were less than 1% of total accumulated germination recorded during the study.I. pectinataandZ. aragonensisseeds buried and exposed to natural seasonal temperature variations in an unheated greenhouse came out of conditional dormancy in summer and re-entered it in winter, thus exhibiting an annual conditional dormancy/non-dormancy cycle. Dormant seeds of both species which were stratified at 28/14 or 32/18°C during an 8-week period, were non-dormant when they were subsequently incubated over a range of temperatures from 5 to 25/10°C. Non-dormant seeds were induced into dormancy when stratified at 5 or 15/4°C for 8 weeks, showing a particularly low germination response at high temperatures. Recommendations for wild-population reinforcement programmes and for the management of the natural habitat of both endemics are discussed.