
TY  - JOUR
A1  - Goldstein, G 
A1  - Andrade, JL 
A1  - Nobel, PS 
T1  - Differences in Water Relations Parameters for the Chlorenchyma and the Parenchyma of <I>Opuntia ficus-indica</I> Under Wet Versus Dry Conditions
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 1991
VL  - 18
IS  - 2
SP  - 95
EP  - 107
KW  - 
UR  - https://doi.org/10.1071/PP9910095 
N2  - 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. 
ER  -

