EFFECT OF CARBON DIOXIDE ON ABSORPTION OF WATER AND NUTRIENTS BY ROOTS

Abstract

The importance of soil aeration to plant development has been recognized since the beginnings of agriculture. As our knowledge of the physiology of roots has grown, the beneficial effects of soil aeration have been assigned to a stimulation of root growth (4) and thus an increase of root area and penetration, and more recently to a direct stimulation of aerobic processes of salt accumulation. Hoagland and his associates particularly have shown that the rate of mineral accumulation in roots containing respirable carbohydrates may be positively correlated with the oxygen supply (8, 24). Although many data upon the toxic effect of carbon dioxide on protoplasm are available, this phase of the soil aeration problem has been generally overlooked. Free (7) and Kramer (16) have shown a reduction of water absorption by roots with increased C02 concentrations. Hoagland and Broyer (9), however, thought the effect of C02 related to its displacement of oxygen, and Arrington and Shive (3) concluded that reduced C02 concentrations were not a factor in the beneficial effects of the aeration of a