Table 1.
Effect of salinity on rate of photosynthesis and transpiration, water-use efficiency and total leaf area in Nerium oleander plants after about 1 month of exposure to 100 mm NaCl as affected by ammonium or nitrate as the nitrogen source
| NH4+-N |
NO3−-N |
|||
|---|---|---|---|---|
| 0 | 100 | 0 | 100 | |
| Photosynthetic rate (μmol CO2 m−2 s−1) | 8·0 ± 0·44a | 4·7 ± 0·54b | 7·6 ± 0·29a | 5·3 ± 0·46b |
| Transpiration rate (mmol H2O m−2 s−1) | 5·4 ± 0·27a | 5·4 ± 0·41a | 4·7 ± 0·26a | 4·7 ± 0·32a |
| Water-use efficiency (μmol CO2 fixed per mmol water lost) | 1·48 ± 0·13ab | 0·87 ± 0·14c | 1·62 ± 0·12a | 1·13 ± 0·15bc |
| Leaf area (cm2) | 1740 ± 106a | 981 ± 74b | 1644 ± 73a | 1178 ± 93b |
Values are means ± s.e. of four replicate plants. Rows not sharing the same letter indicate significant differences between treatments according to the l.s.d. test (P < 0·05).