Nutrient Levels and Salinity Affect Gender and Floral Traits in the Autogamous Spergularia marina

Abstract

The effects of nutrient levels and salinity on prezygotic components of gender (number of ovules and of anthers per flower), on secondary accessory structures (number and size of petals), and on possible indicators 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 hydroponic tubs. Mean ovule number and mean staminode number per flower were not affected by changes in nutrient levels and salinity, while mean anther number per flower decreased and mean petal size increased under the harsher growing conditions (low-nutrient level or salinity). Mean petal and abnormal anther numbers per flower were affected by nutrient levels but not by the salinity treatment. We observed few significant phenotypic correlations among the seven studied traits but observed strong phenotypic correlations between petal number and abnormal anther number under all growing conditions. The overall lack of treatment-specific correlations indicates that evolutionary trajectories in this species may not be strongly affected by the environmental conditions under which natural selection occurs. In contrast to other studies, we report that, for traits expressed prior to pollination, male reproductive traits (number of normal and abnormal anthers per flower) were more sensitive to growing conditions than were traits related to female reproduction (ovule number per flower). Finally, in partial opposition to our initial prediction, we found that the anther/ovule ratio was highly sensitive to salinity but not to nutrient level.