Table 2.
Analysis of covariance of the number of seeds released (log transformed after adding 1) in the wind tunnel experiment. (Only heads from which at least one seed released were included in this analysis. The main factors were air flow turbulence, flower head wetness and flower head temperature. The order of the covariates (the number of seeds that had already fallen from the flower head, the square of that number, the diameter of the flower head and its vertical angle) did not influence whether or not they were significant. Random block effects were accounted for in the error term of the model. (*)p<0.1; *p<0.05; **p<0.01; ***p<0.001.)
| Carduus acanthoides | Carduus nutans | |||||
|---|---|---|---|---|---|---|
| d.f. | MS | F | d.f. | MS | F | |
| no. of seeds already fallen | 1 | 0.21 | 0.48 | 1 | 9.03 | 10.57** |
| (no. of seeds already fallen)2 | 1 | 2.27 | 5.09* | 1 | 13.12 | 15.35*** |
| flower head diameter | 1 | 3.63 | 8.13** | 1 | 0.26 | 0.30 |
| flower head angle | 1 | 1.37 | 3.06(*) | 1 | 0.20 | 0.23 |
| turbulence | 3 | 2.78 | 6.23*** | 3 | 8.45 | 9.89*** |
| wetness | 2 | 4.64 | 10.40*** | 2 | 14.75 | 17.26*** |
| temperature | 1 | 0.70 | 1.57 | 1 | 0.02 | 0.03 |
| turbulence×wetness | 6 | 0.99 | 2.21* | 6 | 0.68 | 0.79 |
| turbulence×temperature | 3 | 1.32 | 2.95* | 3 | 1.53 | 1.79 |
| wetness×temperature | 2 | 0.01 | 0.01 | 2 | 0.21 | 0.24 |
| turbulence × wetness × temperature | 6 | 0.44 | 0.98 | 6 | 0.63 | 0.73 |
| residuals | 107 | 0.45 | 137 | 0.85 | ||