Table 5. Regression Correlation between Cd Contents in the Edible Shoots of Pak choi and Different Forms of Cd in Various Soils.
| Soil type | Form of Soil Cd | Regression equation | R2 |
| Mollisols | Total Cd | y = 2.1706x +0.1669 | 0.99 |
| Mehlich-3 extractable Cd | y = 5.7207x +0.7037 | 0.98 | |
| Ustic Cambosols | Total Cd | y = 2.9358x −0.9586 | 0.96 |
| Mehlich-3 extractable Cd | y = 7.0409x +0.7648 | 0.97 | |
| Stagnic Anthrosols | Total Cd | y = 2.2344x −0.5651 | 0.98 |
| Mehlich-3 extractable Cd | y = 5.3848x +0.4458 | 0.99 | |
| Periudic Argosols | Total Cd | y = 11.061x +0.6961 | 0.98 |
| Mehlich-3 extractable Cd | y = 22.326x +1.3968 | 0.99 | |
| Typic Haplustalfs | Total Cd | y = 8.7318x −4.0825 | 0.97 |
| Mehlich-3 extractable Cd | y = 19.123x −0.8046 | 0.98 | |
| Udic Ferrisols | Total Cd | y = 6.6697x −2.7793 | 0.97 |
| Mehlich-3 extractable Cd | y = 14.873x −0.3773 | 0.99 | |
| Calcaric Regosols | Total Cd | y = 0.8936x +0.924 | 0.95 |
| Mehlich-3 extractable Cd | y = 3.5937x +1.1512 | 0.98 |