High-Resolution Measurements of Transient Changes in the Growth Rate of Intact Lupin Seedlings

Abstract

Measurements of the growth rate of intact lupin seedlings were made under steady-state conditions and as the environment was altered. Although the growth rate frequently changed smoothly with the new condition, there were several cases where periodicity or oscillations in the growth rate were observed. These cases included growth oscillations induced by: the solution in which the roots were immersed being changed back from a mannitol solution to water; the replacement of anaerobic conditions by air or oxygen; the tension being increased on the hypocotyl; and, under some condi- tions, the addition or removal of high CO₂ concentrations. The observed periodicity is more complex than is accounted for by a simple relationship of the minimum yield stress increasing or decreasing with the growth rate, but more information is needed to develop a better model.