Effects of Young Cladodes on the Gas Exchange of Basal Cladodes of Opuntia ficus‐indica (Cactaceae) under Wet and Dry Conditions

2005 ◽  
Vol 166 (6) ◽  
pp. 961-968 ◽  
Author(s):  
Eulogio Pimienta‐Barrios ◽  
Julia Zañudo‐Hernández ◽  
Park S. Nobel
Keyword(s):  
Gas Exchange ◽  
Opuntia Ficus Indica ◽  
Dry Conditions

Differences in Water Relations Parameters for the Chlorenchyma and the Parenchyma of Opuntia ficus-indica Under Wet Versus Dry Conditions

1991 ◽  
Vol 18 (2) ◽  
pp. 95 ◽  
Author(s):  
G Goldstein ◽  
JL Andrade ◽  
PS Nobel
Keyword(s):  
Osmotic Pressure ◽  
Water Relations ◽  
Water Storage ◽  
Dry Weight ◽  
High Water ◽  
Opuntia Ficus Indica ◽  
Large Numbers ◽  
Parenchyma Cells ◽  
Storage Parenchyma ◽  
Dry Conditions

Water relations of the photosynthetic tissue (chlorenchyma) and of the water-storage parenchyma were studied for well watered and droughted Opuntia ficus-indica, a crassulacean acid metabolism plant cultivated worldwide for its fruits and cladodes. For well watered plants, die1 changes in osmotic pressure were evident in the chlorenchyma. Droughting the plants for 4 months resulted in a massive loss of water from the cladodes, particularly from the water-storage parenchyma, which could lose up to 82% of the water present at full turgor without irreversible tissue damage. Pressure-volume curves indicated a decrease in the osmotic pressure at full turgor of about 0.1 MPa for the water-storage parenchyma cells during drought; such a decrease of osmotically active solutes was consistent with the appearance of large numbers of starch grains. The bulk modulus of elasticity was 0.36 MPa for the water-storage parenchyma cells and 2.5-fold higher for the chlorenchyma cells, which were smaller with thicker cell walls than the former cells. Mucilage, a polysaccharide occurring extracellularly, constituted about 14% of the cladode dry weight; it could hold more than 30% of the total water content of the water-storage parenchyma. Polymerisation of sugars, large elastic cells in the water-storage parenchyma and mucilage with its high water-holding capacity helped maintain a positive turgor in the photosynthetic tissue, even after 4 months of drought.

scholarly journals Ecophysiology of young stems (cladodes) of Opuntia ficus-indica in wet and dry conditions

2012 ◽  
Vol 69 (2) ◽  
pp. 232-239 ◽  
Author(s):  
EULOGIO PlMIENTA-BARRIOS ◽  
JULIA ZAÑUDO HERNÁNDEZ ◽  
ALEJANDRO MÜÑOZ-ÜRiAS ◽  
CELIA ROBLES-MURGUÍA
Keyword(s):  
Opuntia Ficus Indica ◽  
Dry Conditions

Tissue gas stores of the body and head-out immersion in humans

1993 ◽  
Vol 75 (3) ◽  
pp. 1285-1293 ◽  
Author(s):  
M. H. Liner
Keyword(s):  
Gas Exchange ◽  
Blood Volume ◽  
Impedance Cardiography ◽  
Venous Blood ◽  
The Body ◽  
Peripheral Blood Flow ◽  
Dry Conditions ◽  
Qualitative Models ◽  
The Difference ◽  
Venous Blood Volume

Breath-by-breath gas exchange was studied in 10 subjects during and after transitions between dry conditions and head-out immersion in thermoneutral conditions. Cardiac index (CI) was estimated by means of impedance cardiography. Previous largely qualitative models of changes in tissue gas stores after blood volume shifts could be confirmed and extended to include a quantitative analysis of O2 and CO2 tissue stores. An increase in CI by 47.0% during immersion was associated with an increase in the tissue O2 stores by 122 ml/m2 and a decrease in the tissue CO2 stores by 148 ml/m2. The time constants for the recovery of O2 uptake (tau O2) and CO2 elimination after initial increases after the dry-to-immersion transition were 32.4 and 79.3 s, respectively. The decrease in CI on return to the dry conditions was associated with a drop in tissue O2 stores and a tau O2 of 144 s. The increase in tissue O2 stores during immersion as well as the difference in tau O2 between the two transitions were larger than could be explained by the change in CI only. This was attributed to changes in the distributions of peripheral blood flow and venous blood volume. Compared with the O2 stores, the decrease in CO2 stores was better predicted by the change in CI. The present results emphasize that the changes in pulmonary and tissue gas exchange imposed by head-out immersion transients mainly reflect movement of gas in and out of body stores.

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