METABOLIC ACTIVITY OF FLOAT-TOBACCO TRANSPLANT ROOTS1

Abstract The nutrient solution in the tobacco-transplant float system is not usually circulated or aerated, and may thus become stagnant and deficient in oxygen. In this system, plants produce media, water and spiral roots. The metabolic activity of these root types during seedling development was investigated in a standard float system and under a low oxygen (near-anaerobic) regime. Oxygen consumption by tobacco seedling root tips was measured using a microsensor. The effects of near-anaerobic conditions on seedling development in a float system reduced dry matter accumulation of both media and water roots. Media roots and spiral roots had a similar metabolic activity rate, and a much greater rate of oxygen uptake than did water roots. The near-anaerobic condition in the float system was less deleterious to media roots than water roots.