Germination in Stylosanthes humilis Populations in the Presence of NaCl

Abstract

The germination response to NaCl treatments (0, 67, 134, 201 and 268 mol m^-3) was investigated in 6 natural populations of Stylosanthes humilis from 3 ecogeographic regions of Pernambuco State, north-east Brazil. In general, salt tolerance was high, with percentage germination unaltered up to 67 mol m^-3 NaCl in 2 populations and unaltered up to 134 mol m^-3 NaCl in the remaining 4. The estimated concentration which reduced percentage germination to 50% varied between populations from 200 to 295 mol m^-3 NaCl. Salt affected germination rate even more than it did the germination percentage, being altered at 67 mol m^-3 NaCl in all populations. The germination rate was reduced to 50% in the range of 131-176 mol m^-3 NaCl. There was a significant variation in salt tolerance between these natural populations, and no relation was found between salt tolerance of the populations and the aridity of their provenance.