Water uptake and growth of cucumber plants (Cucumis sativus L.) under control of dissolved O2 concentration in hydroponics.
Dissolved O2 concentration ([O2]) in nutrient solution was controlled at 0.01, 0.10 and 0.20 mM with accuracy of +/- 0.005 mM in a newly developed hydroponic system, and the effects of [O2] on water uptake and growth of cucumber plants (Cucumis sativus L.) were analyzed. For evaluating water uptake rate under the control of [O2], water flux at the stem base was measured on-line with +/-5% in accuracy, 1 mg s-1 in resolution and 1 min in time constant by heat flux control (HFC) method. Water uptake rate was drastically increased by lighting to the plant at each [O2], and water uptake per day was depressed in proportion to decrease in [O2]. In the plants grown for 10 days, leaf area, fresh weight and dry weight of leaves decreased at lower [O2], while stem length and number of leaves were scarcely affected. These facts suggest that membrane permeability of root cells reduces at lower [O2] through respiration-dependent processes, and growth is inhibited through leaf turgor loss caused by the depressed water uptake of roots in O2-deficient nutrient solution in hydroponics.
Yoshida
S
S
Biotron Institute, Kyushu University, Hakozaki, Japan.
Kitano
M
M
Eguchi
H
H
D018533:Biomass; D018553:Cucumis sativus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D003470:Culture Media; D004305:Dose-Response Relationship, Drug; D018527:Hydroponics / Q000295:instrumentation*; D008027:Light; D010100:Oxygen / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D014867:Water / Q000378:metabolism*
D003470:Culture Media; D014867:Water; D010100:Oxygen