NUTRIENT LEVELS AND SALINITY AFFECT GENDER AND FLORAL TRAITS IN THE AUTOGAMOUS SPERGULARIA-MARINA

The effects of nutrient levels and salinity on prezygotic components o f gender (number of ovules and of anthers per flower), on secondary ac cessory structures (number and size of petals), and on possible indica tors of normal development (number of abnormal anthers and staminodes) were investigated for six maternal families of the highly autogamous Spergularia marina, cultivated under controlled conditions in hydropon ic tubs. Mean ovule number and mean staminode number per flower were n ot affected by changes in nutrient levels and salinity, while mean ant her number per flower decreased and mean petal size increased under th e harsher growing conditions (low-nutrient level or salinity). Mean pe tal and abnormal anther numbers per flower were affected by nutrient l evels but not by the salinity treatment. We observed few significant p henotypic correlations among the seven studied traits but observed str ong phenotypic correlations between petal number and abnormal anther n umber under all growing conditions. The overall lack of treatment-spec ific correlations indicates that evolutionary trajectories in this spe cies may not be strongly affected by the environmental conditions unde r which natural selection occurs. In contrast to other studies, we rep ort that, for traits expressed prior to pollination, male reproductive traits (number of normal and abnormal anthers per flower) were more s ensitive to growing conditions than were traits related to female repr oduction (ovule number per flower). Finally, in partial opposition to our initial prediction, we found that the anther/ovule ratio was highl y sensitive to salinity but not to nutrient level.