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Water Potentials For Developing Cladodes And Fruits Of A Succulent Plant, Including Xylem-Versus-Phloem Implications For Water Movement, P. Nobel, J. Andrade, N. Wang, Gretchen North
Water Potentials For Developing Cladodes And Fruits Of A Succulent Plant, Including Xylem-Versus-Phloem Implications For Water Movement, P. Nobel, J. Andrade, N. Wang, Gretchen North
Gretchen North
Developing cladodes had lower water potentials and developing fruits had higher water potentials than the underlying cladodes of the widely cultivated prickly pear cactus, Opuntia ficus-indica. The 0.06 MPa lower value in 4-week-old daughter cladodes indicated a typical water potential gradient from the underlying clad-ode along the xylem of −0.2 MPa m−1; the 0.17 MPa higher value in 4-week-old fruits, which decreased to 0.07 MPa by 10 weeks, implicated the phloem as their supplier of water. The phloem sap of the underlying cladodes had an osmotic pressure of only 0.90 to 0.98 MPa, so the phloem could supply a relatively …
Changes In Root Hydraulic Conductivity For Two Tropical Epiphytic Cacti As Soil Moisture Varies, Gretchen North, P. Nobel
Changes In Root Hydraulic Conductivity For Two Tropical Epiphytic Cacti As Soil Moisture Varies, Gretchen North, P. Nobel
Gretchen North
The tropical epiphytic cacti Epiphyllum phyllanthus and Rhipsalis baccifera experience extreme variations in soil moisture due to limited soil volumes and episodic rainfalls. To examine possible root rectification, whereby water uptake from a wet soil occurs readily but water loss to a dry soil is minimal, responses of root hydraulic conductivity (Lp) to soil drying and rewetting were investigated along with the underlying anatomical changes. After 30 d of soil drying, Lp decreased 50%-70% for roots of both species, primarily because increased suberization of the periderm reduced radial conductivity. Sheaths composed of soil particles, root hairs, and mucilage covered young …
Cladode Development For Opuntia Ficus-Indica (Cactaceae) Under Current And Doubled Co2 Concentrations, Gretchen North, T.L. Moore, P.S. Nobel
Cladode Development For Opuntia Ficus-Indica (Cactaceae) Under Current And Doubled Co2 Concentrations, Gretchen North, T.L. Moore, P.S. Nobel
Gretchen North
Morphological and anatomical changes for first-order daughter cladodes (flattened stem segments) of a prickly pear cactus, Opuntia ficus-indica, were monitored to determine the effects of a doubled atmospheric CO2 concentration on their development and mature form. For daughter cladodes developing in controlled environment chambers for 60 d, maximal elongation rates were similar under a photosynthetic photon flux density (PPFD) of 6 mol m-2 d-1 and a CO2 concentration of 370 μl liter-1, an increased PPFD (10 mol m-2 d-1), and an increased PPFD and a doubled CO2 concentration. These maximal rates, however, occurred at 20, 15, and 12 d, respectively. …