Physiological dormancy in seeds of two endemic species of Begonia from Yunnan Province, China: diagnosis and classification

Abstract

With the purpose of assessing the status of dormancy in seeds of two Begonia species (Begonia lithophila and Begonia guishanensis), freshly matured seeds were given gibberellic acid and moist chilling and allowed to dry after ripening. The seeds were then germinated on media with or without KNO3 at 15, 20, 25, 30 and 18/25°C. All three treatments significantly increased germination percentages. Examination by X‐ray revealed that seeds of both species have a fully developed embryo and thus have no morphological component of dormancy; seeds readily imbibed water and KNO3 solution. Therefore, we conclude that seeds of the two Begonia species have non‐deep physiological dormancy. Although KNO3 significantly increased germination in both species, alternating temperatures did not, suggesting that the most favorable microhabitat for germination is small‐scale disturbances under the forest canopy.

Effect of temperature and moist conditions on seed dormancy cycling of two sympatric limestone species, Begonia guishanensis and Paraisometrum mileense, in southern China

“…For the DAR treatment, seeds were placed on dry filter paper in 90-mm Petri dishes with lid off at both temperatures. For the MC treatment, seeds were sowed on 1% agar water medium in 90-mm Petri dishes with lid on and were sealed in transparent plastic bags at only 15/5°C because some seeds of both species can germinate at 25/15°C (Hu et al, 2012; Liu et al, 2015). For all treatments, the photoperiod was 12 h light (22.2 μmol m −2 s −1 illumination by cool white fluorescent light) and 12 h dark.…”

“…Embryos of both species are fully developed (Hu et al, 2012; Liu et al, 2015). Seeds of both species are dispersed at the end of the wet season, and they are known to have non-deep physiological dormancy (PD) (Hu et al, 2012; Liu et al, 2015). However, dormancy levels of P. mileense seeds are usually low and are expressed only at temperatures below 20°C (Liu et al, 2015).…”

“…However, dormancy levels of P. mileense seeds are usually low and are expressed only at temperatures below 20°C (Liu et al, 2015). GA 3 , dry afterripening (DAR) and moist chilling (MC) are able to break the dormancy, and KNO 3 significantly enhances the germination of both species (Hu et al, 2012; Liu et al, 2015).…”

“…We speculated that seed dormancy might play a role in the rarity of B. guishanensis seedlings during the wet season, and this dormancy could be induced during the transition between the dry and the wet season. DAR at room temperature and MC at 5°C are able to break dormancy for seeds of B. guishanensis (Hu et al, 2012), but the effects of WD cycles at relatively high temperatures are unknown for both species. Also, the effects of DAR and MC under the natural temperatures (5.5–17.8°C) that occur at the beginning of the dry season have not been determined for either species.…”

Short Communication: Seed germination of twelve Indonesian begonias for conservation

“…Begonia is considered to have seeds without endosperms or only with a little endosperm (Tebbitt and Garden 2005;Haba 2015). Furthermore, the embryo in the germination of Begonia seeds filled all the inside of the fully developed seed shell according to Hu et al (2012) used X-ray exposure.…”