GERMINATION CAPACITY IN SPECIES OF THE MEDITERRANEAN ANNUAL GRASSLAND .2. EFFECT OF THE SEED PRODUCTION YEAR

Initial quality of seeds determine their germination, vigour and longevity and condition potential self-sowing for replacing adult plants in natural vegetation. Since those responses are correlated with natural conditions of the region during seed development, the effect of environmental differences among different seed production years in the same location was investigated for five species of natural grassland. Seed quality of two Geraniaceae (E. moschatum and E. malacoides) and three Poaceae (H. murinum, B. berterianus and A. barbata) collected in 1983, 1985, 1988, 1989 and 1990 was analyzed. Tests were carried out at 15-degrees-C to determine germination capacity, kinetics and velocity by means of five parameters. Electric conductivity and cold tests for vigour were conducted as well. Germination velocity changed in Poaceae while germination capacity showed differences in Geraniaceae, only with intact seeds. Electric conductivity confirmed these results and cold tests with the 1986 collection showed growth reduction in H. murinum. There was a relationship between these results and total rainfall and its spring distribution.