Table 1 Effect of N addition on leaf, stem, and root biomass of P. tabuliformis (mean ± SE, n = 5)
Biomass (g plant−1) | N treatment (g N kg−1) | |||||
|---|---|---|---|---|---|---|
N1 (0.02) | N2 (0.04) | N3 (0.08) | N4 (0.16) | N5 (0.32) | CK (control) | |
 Leaf biomass | 19.4 ± 0.6 ab | 19.9 ± 2.7 a | 21.8 ± 2.1 a | 14.5 ± 1.3 b | 8.8 ± 0.6 c | 17.0 ± 1.5 b |
 Stem biomass | 9.8 ± 1.2 a | 11.6 ± 1.9 a | 10.0 ± 1.5 a | 5.9 ± 0.6 b | 4.0 ± 0.5 b | 10.5 ± 1.4 a |
 Root biomass | ||||||
  First-order roots | 1.3 ± 0.3 ab | 1.2 ± 0.4 ab | 1.7 ± 0.4 a | 1.5 ± 0.4 a | 0.5 ± 0.1 b | 1.2 ± 0.3 ab |
  Second-order roots | 1.8 ± 0.2 a | 2.5 ± 0.1 a | 2.2 ± 0.2 a | 1.9 ± 0.4 a | 1.1 ± 0.1 b | 2.2 ± 0.3 a |
  Third-order roots | 2.4 ± 0.3 ab | 3.1 ± 0.4 b | 2.6 ± 0.2 ab | 2.3 ± 0.3 ab | 1.8 ± 0.3 a | 2.4 ± 0.2 ab |
  Fourth-order roots | 2.6 ± 0.3 ab | 2.9 ± 0.2 ab | 3.0 ± 0.2 a | 2.0 ± 0.3 bc | 1.6 ± 0.1 c | 2.1 ± 0.1 bc |
  Fifth-order roots | 1.7 ± 0.2 ab | 2.4 ± 0.4 a | 1.5 ± 0.4 ab | 2.1 ± 0.5 ab | 1.2 ± 0.2 b | 1.3 ± 0.2 ab |
  Sixth- and above order roots | 3.1 ± 0.7 a | 3.2 ± 0.5 a | 2.8 ± 0.3 a | 2.8 ± 0.1 ab | 1.2 ± 0.2 b | 2.8 ± 0.5 a |
  First- and second-order roots | 3.1 ± 0.5 a | 3.7 ± 0.4 a | 3.9 ± 0.5 a | 3.3 ± 0.7 a | 1.5 ± 0.1 b | 3.4 ± 0.6 a |
  Third- and above order roots | 9.3 ± 0.6 ab | 11.0 ± 1.2a | 9.3 ± 0.7 ab | 8.1 ± 0.9 b | 5.8 ± 0.3 c | 8.0 ± 0.2 b |
 Total root biomass | 13.0 ± 0.7 ab | 15.2 ± 1.1 a | 13.8 ± 0.8 ab | 11.9 ± 1.6 b | 7.3 ± 0.4 c | 12.0 ± 1.0 b |
  First- to second-order roots and leaves | 22.6 ± 0.9 a | 23.6 ± 2.5 a | 25.7 ± 1.7 a | 17.8 ± 0.8 c | 10.3 ± 0.5 d | 20.5 ± 1.2 b |
  Third- and above order roots and stems | 19.6 ± 1.1 a | 23.1 ± 1.4 a | 19.9 ± 1.9 a | 14.6 ± 1.4 b | 9.8 ± 0.3 c | 19.1 ± 1.4 a |
 Total plant biomass | 42.2 ± 1.6 a | 46.7 ± 3.6 a | 45.6 ± 3.4 a | 32.4 ± 1.9 b | 20.1 ± 0.8 c | 39.6 ± 2.3 ab |