EFFECT OF TEMPERATURE AND OXYGEN TENSION ON ROOT GROWTH, CELL CYCLE AND CELL ELONGATION

This paper reports the results of a study of root growth, the duration of the division cycle and the cell size in onion roots (Allium cepa) at different temperatures (5, 15, 25, 30, and 35° C) and at different oxygen tensions (2, 5, 10, and 20% at 25° C). The growth rate increases with the temperature up to a maximum between 25 and 30° C, while the division cycle shows a minimum duration between 30 and 35° C and the final size of the epidermic cells remains constant from 5 to 25° C decreasing from this temperature onwards. The oxygen tension shows a marked effect in conditioning the root growth. The growth rate increased the slower the nearer the oxygen tension was to the concentration found in the air. The division cycle appears to be strongly dependent on this environmental factor, whereas the final cell size is observed to be constant at all the oxygen tensions tested. There follows a discussion of the effects of the various environmental factors on root growth and on its components, namely cell formation and cell elongation. © 1969 Springer-Verlag.