VARIATION IN GERMINATION AND SURVIVAL AMONG FAMILIES OF SAGITTARIA-LATIFOLIA IN RESPONSE TO SALINITY AND TEMPERATURE

We studied seed germination and seedling growth in eight maternal families of Sagittaria latifolia (Alismataceae), a freshwater perennial, in response to salinity (four levels) and temperature effects (two levels) in the greenhouse. Salinity decreased germination, delayed emergence, and decreased survival and growth rates. The negative effects of salinity on germination were greater at the high-temperature regime, but the effects on growth were greater at the low-temperature regime. Some seeds were capable of germinating and surviving (with minimal growth) even in 0.8% NaCl solution. Families also differed in their response to salinity but not to temperature. In particular, high salinities had little effect on the germination of some families. Growth rate always decreased with increasing salinity, but again the magnitude of the effect differed among maternal families. Our data show that S. latifolia can germinate but cannot grow well under low-salinity conditions; thus, S. latifolia might be minimally affected by short-term salt intrusions. In order to understand how plant populations respond to disturbances, such as increased salinity or increased temperature, we need to consider the source, either environmental or genetic, of maternal effects.