Electrophoretic and morphological differentiation of Piceasitchensis, Piceaglauca, and their hybrids

Isozymes and seedling morphology were used to differentiate among nine reforestation seed lots that included three Piceasitchensis (Bong.) Carr., two Piceaglauca (Moench) Voss, and four putative hybrid spruces from the coast–interior zone of reported introgression in British Columbia. Among 18 isozymes, 6 (Adh, Dia-2, Gdh, G6p, 6pg-1, and 6pg-3,) were most useful in separating P. sitchensis and P. glauca. 6pg-1 was the best single criterion to differentiate among the seed lots. Among 10 morphological characteristics, 5 (pattern of terminal bud set when photoperiod was reduced to 15 h, to 14 h 10 min, and to 13 h 25 min, shoot length at end of growing season, and degree of needle serration) were highly variable among seed lots. Pattern of terminal bud set when photoperiod was reduced to 14 h 10 min and degree of needle serration were the two best morphological criteria for seed lot differentiation. Electrophoretic and morphological data were in complete agreement with respect to species classification for the nine seed lots. Such results suggested that isozymes would be useful for taxonomic classification of spruce seed lots collected in areas where introgressive hybridization of P. sitchensis and P. glauca has been reported.