FLUORESCEIN DIACETATE AS A VIABILITY STAIN FOR TREE ROOTS AND SEEDS

Fluorescein diacetate (FDA) was tested as a viability stain for roots of green ash as well as for seeds of green ash and 10 other tree speci es. The viability level indicated by FDA staining of green ash roots a greed well with root growth potential results, bud condition assessmen t, and foliage browning measurements. In seed viability experiments, t he FDA staining intensity of embryos was related to germination in 9 o ut of 11 species tested using a 30 minute stain incubation period. In the other 2 species, eastern hemlock and Scotch pine, embryo FDA stain ing intensity and germination were also similar, provided an 18 h stai n incubation period was used. When two seedlots of differing viability were tested in each of white spruce, Douglas-fir, and pitch pine, sig nificantly higher germination was reflected in significantly higher em bryo FDA staining intensity. In Sitka spruce seed that was heat treate d to produce a range of viabilities, the semilog plot of germination ( log scale) and FDA staining intensity of the embryo (linear scale) had an r(2) = 0.95. Based on these preliminary results, FDA shows promise as a rapid viability stain for tree roots and seeds.