The response of snapdragon Antirrhinum maius L., and carnation Dianthus caryophyllus L., to thigmomorphogenic and seismomorphogenic stress

Some effects of a four, five, or six week daily or alternate daily thigmomorphogenic or seismomorphogenic stress on snapdragon Antirrhinum majus L. and carnation Dianthus caryophyllus L. were determined. Thigmomorphogenic stress administered by manual shaking or flexing resulted in stem breakage at certain stages of plant growth. Seismomorphogenic stress from an electric fan caused no stem breakage. Manual shaking led to temporary retardation of plant growth, flexing caused more permanent retardation. The stage of growth at which the stress was initiated resulted in different intensity of growth retardation. Plant height recorded at one or two weekly intervals was the growth parameter most effected. Differences between flowering, flower height and dry weight were not conclusive.