Table 3.
Contribution of inorganic anions to electrical neutrality with cations in the leaf
| Ionic concentration (mEq l–1) | Contribution to electrical neutrality (%) | Contribution of individual anions to electrical neutrality (%) | |||||
|---|---|---|---|---|---|---|---|
| Positive charges of inorganic cations | Negative charges of inorganic anions | Inorganic anions | Organic moleculesa | SO4 2–+PO4 3– | NO3 – | Cl– | |
| BS | 205.83±7.12 | 81.48±8.53 b | 40.6±5.0 b | 59.3±5.0 a | 26.6±2.0 b | 13.1±3.0 ab | 0.9±0.2 b |
| SP | 216.10±8.33 | 108.66±13.48 b | 49.1±4.1 b | 50.9±4.1 a | 42.6±2.8 a | 6.0±1.7 bc | 0.5±0.04 b |
| N | 208.51±1.75 | 75.11±5.33 b | 35.9±2.3 b | 64.0±2.3 a | 16.5±0.6 c | 19.0±2.0 a | 0.4±0.02 b |
| CL | 211.47±6.60 | 146.69±4.71 a | 69.9±2.8 a | 30.1±2.8 b | 20.3±0.9 bc | 1.0±0.3 c | 48.5±2.0 a |
| P-value | ns | *** | *** | *** | *** | *** | *** |
Treatments consisted of the basal nutrient solution (BS) alone or supplemented with 5mM nitrate (N) or the sulphate+phosphate (SP) salt mixture containing the same cationic balance as in the CL and N treatments.
Anions and cations measured to calculate the data in the respective columns were: Cl–, NO3 –, SO4 2–, and PO4 3–anions; and K+, Ca2+, and Mg2+ cations.
Mean values ± SE, n=4–6. Levels of significance: P>0.05 (‘ns’, non-significant differences) and ***P<0.001. ‘Homogeneous group’ statistics were calculated through ANOVA test.
a Not measured: deduced from quantification of inorganic ions.