Contribution à l'étude écologique du complexe orophile Carex sempervirens (Cyperaceae) : étude expérimentale de la germination de populations pyrénéennes

Abstract

R e~u le 28 octobre 198 1 GEORGES, F., et J.-J. LAZARE. 1983. Contribution i 1'Ctude Ccologique du complexe orophile Carex setnpervirens (Cyperaceae): Ctude expkrimentale de la germination de populations pyrCnCennes. Can. J. Bot. 61: 135-141. Dans le cadre de 1'Ctude Ccologique du complexe orophile Carex sempervirens Vill., sont comparCes expkrimentalement les germinations des akknes de deux populations pyrCnCennes choisies comme tCmoins. L'une appartient i la sous-espkce sempervirens a 2n = 30 chromosomes, et l'autre i la sous-espkce grat~itica (Br.-Bl.) C. Vicioso a 2t1 = 34 chromosomes. Vingt-neuf protocoles experimentaux combinant divers prktraitements (stratification, scarification) et conditions de temperature et de lumikre ont Ct C rCalisCs. Les akknes ne manifestent pas de dormance. Les deux populations se comportent differemment: la population de granitica prCsente une trks forte photosensibilitC positive et, en gCnCral, sa vitesse et sa capacitC de germination sont inferieures a celles de la population de sempervirens. Les conditions expkrimentales optimales de germination semblent Stre rCalisCes apres stratification des akknes, en regime photopCriodique de 16 h et a tempkrature continue de 20°C. GEORGES, F., and J.-J. LAZARE. 1983. Contribution i 1'Ctude Ccologique du complexe orophile Carex sempervirens (Cyperaceae): Ctude expkrimentale de la germination de populations pyrCnCennes. Can. J . Bot. 61: 135-141.Within the framework of the ecological study of the orophilous complex Carex sempervirens Vill., the germination of achenes of two Pyrenean populations are compared as references. One of them belongs to the subspecies sempervirens with 2n = 30 chromosomes and the other one to the subspecies granitica (Br.-Bl.) C. Vicioso with 2n = 34 chromosomes. Twenty-nine experimental treatments including various pretreatments (stratification, scarification) and temperature and light conditions were examined. The achenes did not exhibit any dormancy. The behaviour of the two populations was different; the population of the subspecies granitica showed a very important positive photosensibility and, in general, a lower speed and percentage of germination than the population of the subspecies sempervirens. ' The optimum experimental conditions for germination seem to be realized with stratification of achenes, followed by 16 h photoperiods and a constant temperature of 20°C.