The Effect of a Small Axial Pressure on the Growth of the Epicotyl of Vicia Faba Var. Minor Beck

Epicotyls of Vicia faba var. minor Beck, which had been subjected to an axial pressure of 0·5 atm for 48 hr, were 12% shorter than control epicotyls which had supported a negligible load. The state of stress produced in the epicotyl by the axial pressure led to a change in shape which was not accompanied by any change in volume. As the axial pressure of O· 5 atm is regarded as small compared with the point resistance which often has to be overcome by emerging shoots, it is likely that mechanical resistance is an important factor influencing seedling emergence in ordinary soils.