Germination Ecology of Seeds with Nondeep Physiological Dormancy

AbstractThe 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.

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What can routine germination tests in seed banks tell us about the germination ecology of endemic and protected species?

Botany ◽

10.1139/cjb-2017-0003 ◽

2017 ◽

Vol 95 (7) ◽

pp. 673-684 ◽

Cited By ~ 4

Author(s):

Adelaide S. Clemente ◽

Jonas V. Müller ◽

Erika Almeida ◽

Catarina A. Costa ◽

Sara Lobo Dias ◽

...

Keyword(s):

Seed Bank ◽

Incubation Temperature ◽

In Situ Conservation ◽

Germination Percentage ◽

Test Case ◽

Physical Dormancy ◽

Germination Ecology ◽

Physiological Dormancy ◽

Mean Germination Time ◽

Major Factors

Protocols for the conservation of threatened plants are often constrained by the absence of data on germination ecology. However, seed bank managers periodically monitor the viability of stored seed collections using germination tests. Here, we argue that data from those tests can and should be used to provide information on germination requirements of threatened species. Twelve taxa endemic to Portugal were used as a test case to determine the effect of incubation temperature and pretreatments upon germination and to identify major factors eliciting germination and releasing dormancy. We achieved maximum germination percentages >95% for nine taxa. Temperature significantly affected the final germination and mean germination time in most taxa. Maximum and faster germination at cool temperatures (15 °C or alternate 20/10 °C) was the prevailing trend. Cold stratification improved germination in one species, suggesting physiological dormancy. Scarification increased the germination percentage of one species among those expected to exhibit physical dormancy. Seed bank data provided valuable information on germination ecology, which can be used in in-situ conservation and as a baseline for further germination studies. Given the increasing threats to plant diversity, accessibility to seed bank data are paramount.

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Studies on germination ecology and seedlings characteristics of Cleome viscosa as affected by various environmental factors

Pakistan Journal of Botany ◽

10.30848/pjb2020-6(27) ◽

2020 ◽

Vol 52 (6) ◽

Author(s):

Muhammad Mansoor Javaid ◽

Zaigham Abbas ◽

Hasnain Waheed ◽

Athar Mahmood ◽

Tasawer Abbas ◽

...

Keyword(s):

Environmental Factors ◽

Germination Ecology ◽

Cleome Viscosa

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Physiological dormancy in seeds of tropical montane woody species in Hawai`i

Plant Species Biology ◽

10.1111/1442-1984.12295 ◽

2020 ◽

Author(s):

Carol C. Baskin ◽

Jerry M. Baskin ◽

Alvin Yoshinaga ◽

Dustin Wolkis

Keyword(s):

Woody Species ◽

Physiological Dormancy

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Practical Methods for Breaking Seed Dormancy in a Wild Ornamental Tulip Species Tulipa thianschanica Regel

Agronomy ◽

10.3390/agronomy10111765 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1765

Author(s):

Wei Zhang ◽

Lian-Wei Qu ◽

Jun Zhao ◽

Li Xue ◽

Han-Ping Dai ◽

...

Keyword(s):

Seed Germination ◽

Seed Dormancy ◽

Combined Treatment ◽

Individual Treatment ◽

Cold Stratification ◽

Slight Effect ◽

Sowing Depth ◽

Physiological Dormancy ◽

Commercial Breeding ◽

Breaking Seed Dormancy

The innate physiological dormancy of Tulipa thianschanica seeds ensures its survival and regeneration in the natural environment. However, the low percentage of germination restricts the establishment of its population and commercial breeding. To develop effective ways to break dormancy and improve germination, some important factors of seed germination of T. thianschanica were tested, including temperature, gibberellin (GA3) and/or kinetin (KT), cold stratification and sowing depth. The percentage of germination was as high as 80.7% at a constant temperature of 4 °C, followed by 55.6% at a fluctuating temperature of 4/16 °C, and almost no seeds germinated at 16 °C, 20 °C and 16/20 °C. Treatment with exogenous GA3 significantly improved the germination of seeds, but KT had a slight effect on the germination of T. thianschanica seeds. The combined treatment of GA3 and KT was more effective at enhancing seed germination than any individual treatment, and the optimal hormone concentration for the germination of T. thianschanica seeds was 100 mg/L GA3 + 10 mg/L KT. In addition, it took at least 20 days of cold stratification to break the seed dormancy of T. thianschanica. The emergence of T. thianschanica seedlings was the highest with 82.4% at a sowing depth of 1.5 cm, and it decreased significantly at a depth of >3.0 cm. This study provides information on methods to break dormancy and promote the germination of T. thianschanica seeds.

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