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Intervention de l'oxygène atmosphériqoe sur l'absorption d'eau chez Helianthus annuus
Author(s) -
Lascève G.,
Couchat Ph.
Publication year - 1981
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1981.tb06033.x
Subject(s) - darkness , transpiration , helianthus annuus , oxygen , chemistry , photosynthesis , absorption (acoustics) , botany , absorption of water , apoplast , horticulture , sunflower , biology , materials science , organic chemistry , composite material , cell wall
The role of atmospheric oxygen on root water absorption in Helianthus annuus . The effect of atmospheric anoxia on root water absorption was studied. The experiments were carried out on intact young sunflowers in controlled temperature, light and gas environment; roots were kept in aerated nutrient solution at constant temperature. The evolution of root water absorption and transpiration rate was measured continuously. Before the experiment, the plant was preconditioned at a high transpiration rate by illumination or by CO 2 free air in darkness. Then the atmospheric oxygen was suppressed for 1 h, after which the normal conditions were restored. In anoxia and darkness, the root water absorption cannot balance transpiration, so that an important water stress develops in the plant; the light compensates this effect through the photosynthetic oxygen. The supply of oxygen, in darkness or in light, immediately removes inhibition of stomatal closure and of root water absorption. Two mechanisms control water absorption by roots: the fast one occurs in the leaves and the slower one cannot develop without the root system.