Gentiana lutea L. subsp lutea seed germination: natural versus controlled conditions

Gentiana lutea L. subsp. lutea is a geophyte that occurs in the central-southern European mountains. We investigated its germination ecophysiology with the main aim of evaluating seed germination behaviour under controlled and natural conditions. Seeds from four natural sites were tested for germination requirements under a range of different temperatures, and by comparing the results with those obtained under both cold stratification at 5 degrees C and treatment with GA(3). We simultaneously carried out germination tests at each collecting site, and soil temperatures were recorded. Our results indicate that germination under controlled conditions is limited by high temperatures (25 degrees C), below which GA(3) has a remarkable effect on germination percentages. Cold stratification did not have an influence on the germination response, thus suggesting that a temperature of 5 degrees C is not sufficient to break seed dormancy; this result was supported by soil temperatures. Gentiana lutea created a short-term persistent seed bank, and seeds mainly germinated in their first year. The germination under controlled conditions was similar in all accessions, while different responses were found in the field, where a potential influence of the aspect was observed. These findings underscore the importance of understanding germination behaviour in the field to define the real thermal requirements of a taxon.