| Treatment ID | Treatment Name | Best-fit Equation | Correlation coefficient (R2) |
| T1 | Rubber Nut Shell | 4E−06x2 − 0.3624x + 7942.9 | 1 |
| T2 | Rice Husk | 1E−05x2 − 1.0852x + 23783 | 1 |
| T3 | HP wood | 2E−05x2 − 1.6786x + 36785 | 1 |
| T4 | Control | 2E−05x2 − 1.3724x + 30076 | 1 |