Water and Solute Permeability of Plant Cuticles: Measurement and ...

More documents

Recommendations

Info

9.7 Measuring Water Permeability 267 temperature equilibrium and steady state are established before weighing is started. Depending on water permeability, chambers are weighed at intervals of hours or even days to get a significant loss of mass. These intervals are too long for detecting extrapolated hold-up times in the range of 4–15 min (Table 4.10). When we used the cup method, the CM were inserted such that the morphological inner side of the CM was in contact with water while the outer side was exposed to dry air. In this arrangement, driving force was maximum (∆aw = 1.0; ∆Cwv = 23.05g m 3 at 25 ◦ C). With most plant species, swelling of cuticles and permeance depend on partial vapour pressure (Fig. 4.6). When in equilibrium with silica gel the limiting skin is not or very little swollen, and the cup method results in minimum permeances. Humidity in the box does not have to be zero. If constant humidity saturated salt solutions (cf. Greenspan 1977; Kolthoff et al. 1969; Appendix B) or glycerol/water mixtures (Slavik 1974) are used instead of silica gel, humidity can be varied and effects of humidity on permeance can be studied. We have not tried this, however. The cup method has been used extensively because it is simple, cheap, and very accurate, and large sample sizes can be handled (Geyer and Schönherr 1990; Mérida et al. 1981; Riederer and Schönherr 1990; Schönherr and Bauer 1992; Schreiber and Riederer 1996a, b). The cup method resembles the situation in nature, except that in the field humidity is rarely close to zero. It has some other limitations. Water fluxes at 100% humidity cannot be measured, because driving force is zero and no net flux occurs. In this situation, tritiated water (THO) was used as tracer (Schönherr and Schmidt 1979). An aqueous buffer containing THO served as donor in contact with the morphological inner surface of the CM. Air of constant humidity obtained by the dew point method was blown over the outer surface of the CM. The moisture containing the THO which had penetrated was trapped in a dry-ice cold trap (−70 ◦ C), and radioactivity in the cold trap was assayed by scintillation counting (Figs. 4.6 and 4.8). Schreiber et al. (2001) also studied the effect of water activity of the receiver using a slightly different approach. The stainless steel transpiration chamber, with THO as donor solution facing the morphological inner side of the cuticle, was attached upside down to a scintillation vial (Fig. 9.3). Humidity of the receiver (the scintillation vial) facing the morphological outer side of the CM was varied using 100µl glycerol (2% RH), pure water (100% RH) or mixtures of glycerol and water having humidities between 2 and 100% RH (Slavik 1974). The surface of the CM was in contact with the equilibrium vapour pressures of the glycerol/water mixtures, but not with the solutions themselves, which were on the bottom of the vials (500µl). THO which penetrated the cuticle was absorbed in the glycerol, water or glycerol/water mixtures, and after adding scintillation cocktail, radioactivity was determined by liquid scintillation counting. The effect of cations and pH on water permeability of CM or MX membranes was studied using the system buffer/CM or MX/buffer and tritiated water as tracer (Schönherr 1976a, b). If a fine capillary is attached to the receiver containing an osmotic solute, this system can be used to measure osmotic water transport in MX membranes (Fig. 4.9), but it is not sufficiently sensitive for CM (Schönherr 1976a; Schönherr and Mérida 1981).
268 9 General Methods, Sources of Errors, and Limitations in Data Analysis Fig. 9.3 Experimental setup used for measuring the effect of humidity on water permeability. Stainless steel transpiration chambers containing radio-labelled water were mounted upside down on scintillation vials. Inside the vials, various humidities were established using glycerol (2% humidity), glycerol water mixtures (humidity between 2 and 100%) or pure water (100% humidity) 9.8 Measuring Solute Permeability Solute permeability depends on partition coefficients and diffusion coefficients in the cuticle (2.18). Cuticles are heterogeneous membranes, and waxes determine solute permeability. Hence, mobility and sorption of solutes in waxes must be studied, but interactions between waxes and the polymer matrix are also important (Chap. 6). The role of aqueous pores in penetration of ionic solutes is discussed in Chap. 5, and problems related to partitioning and sorption are treated in
Page 2 and 3:
Water and Solute Permeability of Pl
Page 4 and 5:
Professor Dr. Lukas Schreiber Ecoph
Page 6 and 7:
vi Preface This is not a review abo
Page 8 and 9:
Contents 1 Chemistry and Structure
Page 10 and 11:
Contents xi 4.6.3 Diffusion Coeffic
Page 12 and 13:
Contents xiii 7.4.2 Effects of Plas
Page 14 and 15:
2 1 Chemistry and Structure of Cuti
Page 16 and 17:
Page 18 and 19:
Page 20 and 21:
Page 22 and 23:
10 1 Chemistry and Structure of Cut
Page 24 and 25:
Page 26 and 27:
Page 28 and 29:
Page 30 and 31:
Page 32 and 33:
Page 34 and 35:
Page 36 and 37:
Page 38 and 39:
Page 40 and 41:
Page 42 and 43:
Chapter 2 Quantitative Description
Page 44 and 45:
2.1 Models for Analysing Mass Trans
Page 46 and 47:
Page 48 and 49:
Page 50 and 51:
2.3 Steady State Diffusion Across a
Page 52 and 53:
2.4 Steady State Diffusion of a Sol
Page 54 and 55:
2.4 Steady State Diffusion of a Sol
Page 56 and 57:
2.5 Diffusion Across a Membrane wit
Page 58 and 59:
2.5 Diffusion Across a Membrane wit
Page 60 and 61:
2.6 Determination of the Diffusion
Page 62 and 63:
Solutions 51 2.7 Summary In this ch
Page 64 and 65:
Chapter 3 Permeance, Diffusion and
Page 66 and 67:
3.1 Units of Permeability 55 3.1.1
Page 68 and 69:
3.1 Units of Permeability 57 identi
Page 70 and 71:
3.3 Partition Coefficients 59 The d
Page 72 and 73:
Chapter 4 Water Permeability All te
Page 74 and 75:
4.1 Water Permeability of Synthetic
Page 76 and 77:
4.2 Isoelectric Points of Polymer M
Page 78 and 79:
4.2 Isoelectric Points of Polymer M
Page 80 and 81:
4.3 Ion Exchange Capacity 69 The hi
Page 82 and 83:
4.3 Ion Exchange Capacity 71 has an
Page 84 and 85:
4.3 Ion Exchange Capacity 73 Counte
Page 86 and 87:
4.4 Water Vapour Sorption and Perme
Page 88 and 89:
4.4 Water Vapour Sorption and Perme
Page 90 and 91:
4.5 Diffusion and Viscous Transport
Page 92 and 93:
Page 94 and 95:
Page 96 and 97:
Page 98 and 99:
Page 100 and 101:
Page 102 and 103:
Page 104 and 105:
4.6 Water Permeability of Isolated
Page 106 and 107:
Page 108 and 109:
Page 110 and 111:
Page 112 and 113:
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
Page 124 and 125:
Page 126 and 127:
Page 128 and 129:
Page 130 and 131:
Page 132 and 133:
Problems 121 Our present knowledge
Page 134 and 135:
Solutions 123 5. Ca 2+ , because se
Page 136 and 137:
126 5 Penetration of Ionic Solutes
Page 138 and 139:
Page 140 and 141:
Page 142 and 143:
Page 144 and 145:
Page 146 and 147:
Page 148 and 149:
Page 150 and 151:
Page 152 and 153:
Page 154 and 155:
Page 156 and 157:
146 6 Diffusion of Non-Electrolytes
Page 158 and 159:
Page 160 and 161:
Page 162 and 163:
Page 164 and 165:
Page 166 and 167:
Page 168 and 169:
Page 170 and 171:
Page 172 and 173:
Page 174 and 175:
Page 176 and 177:
Page 178 and 179:
Page 180 and 181:
Page 182 and 183:
Page 184 and 185:
Page 186 and 187:
Page 188 and 189:
Page 190 and 191:
Page 192 and 193:
Page 194 and 195:
Page 196 and 197:
Page 198 and 199:
Page 200 and 201:
Page 202 and 203:
Page 204 and 205:
Page 206 and 207:
Page 208 and 209:
Page 210 and 211:
Page 212 and 213:
Page 214 and 215:
Page 216 and 217:
206 7 Accelerators Increase Solute
Page 218 and 219:
Page 220 and 221:
Page 222 and 223:
Page 224 and 225:
Page 226 and 227: 216 7 Accelerators Increase Solute
Page 242 and 243: Chapter 8 Effects of Temperature on
Page 244 and 245: 8.1 Sorption from Aqueous Solutions
Page 246 and 247: 8.1 Sorption from Aqueous Solutions
Page 248 and 249: 8.2 Solute Mobility in Cuticles 239
Page 256 and 257: 8.3 Water Permeability in CM and MX
Page 258 and 259: 8.3 Water Permeability in CM and MX
Page 260 and 261: 8.4 Thermal Expansion of CM, MX, Cu
Page 262 and 263: 8.5 Water Permeability of Synthetic
Page 264 and 265: 8.5 Water Permeability of Synthetic
Page 266 and 267: Problems 257 E D (kJ/mol) DH S (kJ/
Page 268 and 269: Chapter 9 General Methods, Sources
Page 270 and 271: 9.2 Testing Integrity of Isolated C
Page 272 and 273: 9.4 Distribution of Water and Solut
Page 274 and 275: 9.6 Cutin and Wax Analysis and Prep
Page 278 and 279: 9.8 Measuring Solute Permeability 2
Page 284 and 285: 276 Appendix A Abbreviations (conti
Page 286 and 287: 278 Appendix A Symbols (continued)
Page 288 and 289: 280 Appendix B Physico-chemical pro
Page 290 and 291: Appendix C Index of Plants Botanica
Page 292 and 293: References Abraham MH, McGowan JC (
Page 294 and 295: References 287 Doty PM, Aiken WH, M
Page 296 and 297: References 289 Kolattukudy P (2004)
Page 298 and 299: References 291 Sabljic A, Güsten H
Page 300 and 301: References 293 Schreiber L, Schönh
Page 302 and 303: Index 2,4-D, 46 2,4-Dichlorophenoxy
Page 304 and 305: Index 297 leaf disks, 130 leaf surf
Page 306: Index 299 water molar volume, 110 p
show all

Water and Solute Permeability of Plant Cuticles: Measurement and ...

Create successful ePaper yourself

Delete template?

Save as template?