GENETIC-VARIABILITY IN SALT TOLERANCE DURING GERMINATION OF STYLOSANTHES HUMILIS HBK AND ASSOCIATION BETWEEN SALT TOLERANCE AND ISOZYMES

Variation in salt tolerance of six natural populations of Stylosanthes humilis from three ecogeographic regions, Mata (wet tropical climate) , Agreste and Sertao (semi-arid tropical climate) of Pernambuco State, Northeast Brazil, was evaluated on germination in 201 mM NaCl. There were significant differences among families of all populations for ger mination percentage and of five populations (except Tamandare, from Ma ta) for germination rate. Populations from semi-arid regions presented high coefficients of genetic variation, those from Agreste being high er than those from Sertao. Populations from Mata showed low coefficien ts of genetic variation. The coefficients of genotypic determination w ere high for five populations, except Tamandare, both for germination percentage (greater than or equal to 0.89) and for germination rate (g reater than or equal to 0.79), indicating the possibility of selection for salt tolerance in these populations. An electrophoretic analysis of esterase and peroxidase isozymes was also performed in the six popu lations, and correlations were estimated between salt tolerance and al lelic frequencies. The analysis of salt tolerant and salt sensitive fa milies of populations from Agreste suggested an association of alleles of a peroxidase locus with salt tolerance during germination in the C aruaru population.