RELATIONSHIP BETWEEN FIELD PERFORMANCE, FAMILY, EMBRYO MORPHOLOGY, AND ISOZYME HETEROZYGOSITY, AND IN-VITRO REACTIVITY IN JACK PINE

The influence of field performance, family, embryo morphology, and iso zyme heterozygosity level on in vitro reactivity of Pinus banksiana La mb. was evaluated on embryos from five superior families, five inferio r families, and a mixed seed lot. Embryo length, number of cotyledons, and isozyme heterozygosity were determined for each embryo. Seed germ ination and fresh weight were determined on a family level. On average , superior families showed higher percentages of embryos that formed b uds in vitro. Within each performance class, the analysis based on ini tial number of embryos revealed differences among families for the per centage of green embryos and embryos with adventitious buds and shoots . When calculations were based on green embryos only, i.e., excluding embryos that remained white, there were no differences among families. Thus, the overall in vitro potential of a family appears to be strong ly dependent upon the capacity of embryos to turn green. On a per fami ly basis, seed germination was positively correlated with most in vitr o characters, with the exception of mean shoot length per shoot-formin g embryo. Small embryos had a lower probability of producing buds and shoots, and embryos with three cotyledons showed a higher mortality th an embryos with four or more cotyledons. No significant relationships were observed between heterozygosity level and in vitro reactivity, wi th analyses performed on green embryos only.