Photoperiodic Control of Adventitious Stem Initiation on Roots 1

ADVENTITIOUS stem initiation on roots is a common occurrence in nature. This phenomenon is more prevalent among trees and woody shrubs than among herbaceous plants. In the late nineteenth century Holm (6) reported that a list of herbaceous plants producing rootshoots included only 124 dicotyledons and 8 monocotyledons. He reported further that it was a rather scattered occurrence in some 40 families and a constant occurrence only in a small number of genera or species. He also found no correlation between the development of these shoots and environment. But Carnahan (4) and Grey have shown that management influences the creeping-rooted habit of alfalfa, and Daday (5) and Carlson et al, (2) have shown that temperature and day-length influence stem production on roots of alfafa. Since axillary bud production is influenced by photoperiod, it was hypothesized that adventitious stem initiation is similarly affected by photoperiod. The purpose of the present study was to determine the relation of photoperiodic responses of adventitious stem initiation on roots of three diverse long-day species: alfalfa, Medicago sativa. L; crownvetch, Coronilla varia L.; and sheep sorrel, Rumex acetosella. L.