Table 2. The contents of eight phenolic acids in rice root-exudates at 3–6-leaf stage (ng plant−1).
| Phenolic acid | cultivars | 3-leaf | 4-leaf | 5-leaf | 6-leaf |
|---|---|---|---|---|---|
| Protocatechuic acid | PI | 10.58 ± 0.86 | 30.49 ± 5.45 | 14.62 ± 1.13 | 26.82 ± 2.40 |
| TN | 9.36 ± 0.36 | 25.85 ± 1.59 | 14.33 ± 1.25 | 24.09 ± 2.52 | |
| Le | 11.63 ± 0.52 | 22.37 ± 1.32 | 26.74 ± 1.24 | ND | |
| p- Hydroxybenzoic acid | PI | 41.43 ± 1.12 | 674.65 ± 9.89 | 49.46 ± 3.24 | 66.56 ± 2.84 |
| TN | 36.4 ± 2.86 | 566.4 ± 5.26 | 38.4 ± 2.31 | 68.55 ± 3.01 | |
| Le | 52.43 ± 1.14 | 71.23 ± 3.09 | 17.21 ± 1.22 | 28.77 ± 1.93 | |
| Vanillic acid | PI | 15.74 ± 0.99 | 64.14 ± 6.26 | 43.84 ± 6.67 | 78.37 ± 4.62 |
| TN | 14.54 ± 0.82 | 59.39 ± 4.37 | 39.79 ± 3.14 | 74.14 ± 4.84 | |
| Le | 16.14 ± 1.53 | 12.47 ± 3.25 | 13.18 ± 2.29 | 10.99 ± 1.68 | |
| Syringic acid | PI | 59.65 ± 3.28 | 43.06 ± 2.46 | 111.09 ± 5.34 | 282.73 ± 7.96 |
| TN | 56.66 ± 3.76 | 36.87 ± 3.17 | 109.38 ± 6.29 | 315.89 ± 7.15 | |
| Le | 52.66 ± 1.46 | 174.05 ± 6.24 | 102.95 ± 6.21 | 95.42 ± 2.36 | |
| p-Coumaric acid | PI | ND | ND | ND | ND |
| TN | 9.45 ± 0.21 | 16.37 ± 0.75 | 13.41 ± 0.25 | 48.54 ± 1.68 | |
| Le | ND | ND | ND | ND | |
| Ferulic acid | PI | 9.71 ± 0.11 | 19.48 ± 1.21 | 14.67 ± 1.08 | 53.74 ± 3.12 |
| TN | ND | ND | ND | ND | |
| Le | ND | ND | ND | 23.87 ± 1.18 | |
| Salicylic acid | PI | 252.54 ± 7.12 | 499.58 ± 8.02 | 1176.52 ± 11.89 | 1818.59 ± 15.14 |
| TN | 207.23 ± 7.36 | 483.55 ± 6.93 | 1138.91 ± 12.42 | 1362.09 ± 10.22 | |
| Le | 140.99 ± 4.37 | 303.08 ± 8.14 | 888.29 ± 19.51 | 996.66 ± 9.78 | |
| Cinnamic acid | PI | 1.90 ± 0.12 | 15.10 ± 0.31 | 33.59 ± 1.78 | 37.91 ± 2.13 |
| TN | 1.54 ± 0.14 | 14.44 ± 0.93 | 31.56 ± 2.64 | 30.06 ± 2.78 | |
| Le | 1.37 ± 0.38 | 6.79 ± 0.59 | 10.12 ± 2.09 | 4.43 ± 0.26 |
Notes.
Means ± standard error (SE) from three replications for each determination is shown. ‘ND’means compounds not detected in the analysis. PI and TN, allelopathic cultivars PI312777 and Taichung Native1. Le, non-allelopathic cultivar Lemont.