Table 3.
Leaf tissue water content, leaf sap osmotic potential (Ψπsap) and estimation of contribution of ions and sugars towards leaf Ψπsap of chickpea (Rupali) subjected to control or 30mM NaCl treatment either without infusion or with stem-infusion with water or 0.44M sucrose (Ψπ=–1.1MPa)
Plants were grown in nutrient solution culture and NaCl treatment was imposed on 20-day-old plants for 97 d (20/15±2 °C day/night air temperatures). Infusion treatments were started at the time of flowering (42-day-old plants) and continued until maturity. Measurements were taken on the second youngest fully-expanded leaf (petiole+leaflets) after 28 d of infusion treatments, individually for each measurement using samples from different branches of the same plant within each replicate. Values are means±SE (n=4; i.e. four plants in four different pots per treatment). Leaf Ψπsap data are taken from Fig. 4 and the tissue water content data below and tissue ion (Fig. 5; Supplementary Fig. S1) and sugar data (Table 2) were used for the calculation of estimated contributions to leaf Ψπsap. The contribution of a given solute was calculated as: Ψπ=−nRT/V, where n is the number of solute molecules; R, the universal gas constant; T, temperature in °K; and V, volume in L. Values are means±SE (n=4). The value for contribution of sugars would be an overestimate as it uses the total hexose units from Table 2, of which a proportion would have been present in the tissues as sucrose. The osmotic coefficient of the NaCl in the external solution and of Na+ and Cl− in the tissues was assumed to be 1.
| Treatments | External Ψπ (MPa) |
Leaf Ψπsap (MPa) |
Leaf water content (ml g–1 dry mass) |
Estimated contributions of ions and sugars to leaf Ψπsap (%) |
|||||
|---|---|---|---|---|---|---|---|---|---|
| Na+ | Cl− | K+ | Total ions | Sugars | |||||
| Non-saline | No infusion | −0.04 | −0.79±0.01 | 5.3±0.2 | 4.3±0.4 | 5.3±0.2 | 36.0±0.8 | 45.7±1.1 | 2.0±0.0 |
| Water infusion | −0.04 | −0.77±0.02 | 5.2±0.2 | 4.2±0.1 | 5.3±0.4 | 37.3±2.0 | 46.8±1.9 | 2.0±0.1 | |
| Sucrose infusion | −0.04 | −1.08±0.05 | 5.1±0.3 | 3.1±0.2 | 4.0±0.5 | 28.1±2.3 | 35.2±2.7 | 2.2±0.1 | |
| 30mM NaCl | No infusion | −0.16 | −1.60±0.06 | 4.6±0.2 | 8.5±0.4 | 24.6±5.7 | 23.3±1.3 | 56.4±6.6 | 0.9±0.1 |
| Water infusion | −0.16 | −1.56±0.07 | 4.4±0.1 | 9.6±0.4 | 29.5±2.1 | 26.5±0.8 | 65.5±3.0 | 0.9±0.1 | |
| Sucrose infusion | −0.16 | −1.84±0.03 | 4.8±0.1 | 7.5±0.3 | 22.6±1.1 | 19.6±1.2 | 49.7±2.4 | 1.0±0.1 | |