An evaluation of yellow-poplar samaras by radiography

Control-pollinated samaras from 25 clones in a yellow-poplar breeding orchard at the University of Tennessee, Knoxville, were subjected to radiograph and germination analysis. A high correlation was found between filled samaras identified from radiographs and samaras that germinated. Significant differences were observed among clones used as females for percentage filled samaras; no such differences were present among pollen parents. Viability tended to be higher when clones were cross-pollinated than when the same clones were open-pollinated.

Analysis of 62 crosses and their reciprocals indicated significant difference between the two, thus, precluding a partial diallel analysis for viability and indicating a strong maternal effect.

An irradiation (gamma) study revealed that there is no significant effect with respect to germination and seedling dry weight from exposure to doses of radiation up to and including 2500R. Seedling length showed significant differences among treatments below 2500R with the two half-sib families used in the study reacting somewhat differently to the radiation treatment.

Statistical analysis of ten arbitrarily assigned zones of viability within several ripe gynoecia revealed that the topmost and lowermost (basal) samaras on the yellow-poplar cone are generally nonviable.