The Effect of Temperature, Light and Calcium Carbonate on Seed Germination and Radicle Growth of the Polycarpic Perennial Galium cracoviense (Rubiaceae), a Narrow Endemic Species From Southern Poland

Abstract

Germination responses of Galium cracoviense Ehrend. (Rubiaceae), a narrow endemic species from southern Poland, were tested in light and dark conditions at three constant temperatures (5, 10, or 22°C), before and after cold-wet stratification. Additionally, seeds were germinated under different calcium carbonate (CaCO 3 ) concentrations (1, 5, 10, 15, 20, or 25 mM/L CaCO 3 ) at 22°C in light. The high germination capacity of seeds incubated at different temperatures, shortly after collection, already suggested the absence of dormancy in this species. Thus, the seeds are ready to germinate immediately in the field when water resources are available and the temperature is adequate. Light was a significant factor for G. cracoviense; more seeds germinated in light than in darkness at all temperatures tested. Cold stratification decreased germination especially at higher temperatures. The light requirement for G. cracoviense germination ensures their successful germination on or near the soil surface, and in cracks and crevices in limestone, when temperature and edaphic conditions are favourable. Seeds of this species show temperature enforced dormancy throughout the winter. Germination was significantly affected by calcium carbonate. Non-germinated seeds germinated well after being transferred from higher CaCO 3 concentrations to distilled water. The results indicate that the seeds of this species can endure CaCO 3 stress without losing their viability and start germination once CaCO 3 concentration is reduced. It can be concluded that the seeds of this species require lower Ca 2+ ion concentration, moderate temperatures and the presence of light to germinate. K Ke ey y w wo or rd ds s: : Calcium carbonate, dormancy, rare species, recovery.

Differential Response of Groundnut Genotypes for Varying CaCO3 Concentrations

“…The main reason for the reduction in the germination rate is the toxic effects of CO 3 and HCO 3 ions which hinders the water absorption, metabolic and physiological processes of seeds as a result the germination process is delayed. The results were in confirmation with the findings reported by Leblebici and Isık, (2018), Kołodziejek and Patykowsk (2015) in Galium cracoviense seeds and Gadwal and Naik (2014) in Hibiscus species.…”

“…The inhibitory effect on germination index was obvious from 5 mM CaCO 3 L -1 and the maximum reduction was observed at 100 mM CaCO 3 L -1 . This could be ascribed to the higher concentration of exogenous HCO 3 and CO 3ions (Cai et al, 2013;Kołodziejek and Patykowsk, 2015).…”

Plant–plant interactions determine natural restoration of plant biodiversity over time, in a degraded mined land

“…In this regard, some meta‐synthetic studies (Gomez‐Aparicio, 2009 ; He et al, 2013 ) show that growth form and some physiological traits such as leaf carbon and nitrogen content may clearly reflect plant strategies in response to major stress factors, including land use, land degradation, and changing soil nature in degraded ecosystems such as limestone mines (Wang et al, 2021 ). In limestone mines, there is extreme ecological condition in soil by a stronger proportion of calcium carbonate (CaCO3), soluble salts and by its neutrality or even its alkalinity (up to pH = 8.5) that influence plant growth and survival through inhibiting the activity of micro‐organisms, impeding the formation and mineralization of humus, reducing the availability of nitrogen, iron, and phosphorus (Kolodziejek & Patykowski, 2015 ; Nakata, 2015 ). However, mechanisms promoted by nurse species on plants are not clearly recognized about functional traits related to extreme ecological conditions in degraded ecosystems such as limestone mines.…”

Weed Seed Dormancy: The Ecophysiology and Survival Strategies

“…For example, seeds of Galium cracoviense Ehrend. require lower Ca 2+ ion concentration, moderate temperatures, and presence of light to germinate [30]. Garden cress (Lepidium sativum L.) seeds only germinate in response to a combination of light and temperature, while seed germination of Chenopodium album requires treatment with red light, cool temperature, and nitrate.…”