Table 1.
Reproduction and growth of T. triandra under experimental climate treatments. Compared with diploids, seed production and seed viability in tetraploids show a homeostatic response to increasing climate stress, with associated models containing strong cytotype × climate interactions (CY × CL). In contrast, the increase in seed mass and awn length observed in tetraploids was fixed across climate treatments, with only cytotypic effects (CY) being significant. Cytotypic differences were consistent across source regions (SY), with CY × SY interactions being non-significant in eight of nine models.
| model effectsa |
||||
|---|---|---|---|---|
| variable | main | interaction | modelb | figurec |
| viable seed production (dm−2) | CY2.9NS; CL9.5***; SR21.4** | CY × CL5.8***; SR × CL2.0M | HA | 3a |
| viable seed weight (g 10 seeds−1) | CY33.6**; CL8.2**; SR19.8** | CY × SR8.5* | FA | 3b |
| basal area ratio (Apr/Nov) | CY0.6NS; CL14.0***; SR0.1NS | SR × CL3.1** | NA | 3c |
| viable seed production (plant−1) | CY5.4M; CL17.1***; SR22.5** | CY × CL4.6**; SR × CL2.1M | HA | S5a |
| culm production (dm−2) | CY1.4NS; CL2.3NS; SR23.2** | CY × CL4.3**; SR × CL2.5* | HA | S5b |
| floret production (culm−1) | CY4.6M; CL12.2***; SR17.5** | CY × CL2.8* | HA | S5c |
| seed viability (%) | CY20.9**; CL4.8*; SR0.4NS | CY × CL3.0* | HA | S5d |
| basal area (Apr) | CY3.9M; CL25.8***; SR0.9NS | SR × CL3.6** | NA | S5f |
| awn length (mm) | CY29.3**; CL9.2**; SR36.0*** | CY × CL × SR3.3** | FA | S5e |
aCY = cytotype effect (2x versus 4x), CL = climate treatment effect (C, +W, +D, +DW), and SR = source region effect (BBAY, SYDB, ALB). Only highest order model interaction terms significant at the 0.10 level are shown. Subscripts for main and interaction effects indicate F values for fixed effects, evaluated with numerator and denominator degrees of freedom as follows: CY = 1,6; CL = 3,15; SR = 2,6; CY × CL = 3, 178–236; SR × CL = 6, 178–236; CY × SR = 2, 6; CY × CL × SR = 2, 178–236. ***p < 0.001; **p < 0.01; *p < 0.05; MP < 0.10; NSP > 0.10.
bThe relevant polyploid advantage model is taken from figure 4: HA = homeostatic advantage, FA = fixed advantage and NA = no advantage.
cRefers to either figure 3a–c or electronic supplementary material, figure S5a–f.