Table 1.
Kinetic P-uptake parameters (initial [P] = 20 µm) for six genotypes previously grown under P-deficient or P-replete hydroponic conditions
| Pre-treatment | Genotype (tolerance to P deficiency)* | Maximum uptake rate, Imax (μmoles g−1 h−1) | Concentration at half Imax, Km (μm) | Minimum concentration, Cmin (μm) | Maximum uptake rate/efflux rate (Imax/X) |
|---|---|---|---|---|---|
| –P | Kasalath (E) | 13 ± 2 | 1·7 ± 0·6 | 0·22 ± 0·06 | 5·3 ± 2·0 |
| Nerica10 (E) | 8 ± 3 | 1·5 ± 1·1 | 0·15 ± 0·04 | 6·5 ± 0·3 | |
| IAC47 (E) | 26 ± 15 | 7·8 ± 3·9 | 0·19 ± 0·01 | 15·5 ± 4·7 | |
| Dular (E) | 32 ± 12 | 7·1 ± 4·0 | 0·16 ± 0·02 | 17·7 ± 5·3 | |
| Nipponbare (I) | 19 ± 2 | 2·6 ± 0·7 | 0·23 ± 0·07 | 4·1 ± 0·6 | |
| Nerica9 (I) | 28 ± 12 | 6·5 ± 4·1 | 0·21 ± 0·03 | 13·5 ± 7·6 | |
| + P | Kasalath (E) | 6 ± 1 | 1·2 ± 1·0 | 1·3 ± 1·2† | 1·9 ± 0·1 |
| Nerica10 (E) | 8 ± 1 | 1·6 ± 1·6 | 1·3 ± 1·6 | 2·2 ± 0·1 | |
| IAC47 (E) | 8 ± 2 | 2·4 ± 2·1 | 0·6 ± 0·2 | 4·6 ± 2·0 | |
| Dular (E) | 5 ± ± 1 | 1·7 ± 0·3 | 1·6 ± 0·1 | 2·2 ± 0·4 | |
| Nipponbare (I) | 24 ± 17 | 3·5 ± 2·8 | 0·6 ± 0·3 | 2·8 ± 0·7 | |
| Nerica9 (I) | 11 ± 1 | 1·5 ± 0·4 | 0·6 ± 0·1 | 3·4 ± 0·9 |
* The genotypes are categorized as P-efficient (P) or P-inefficient (I), based on tolerance rankings under field conditions.
† Values in bold given under +P conditions represent the concentration in solution after 28 h, at which time it is likely that depletion had not yet ceased.