Results
Tiller number and plant biomass
Tiller number was significantly greater in Monkhead compared with 92-46, but tiller number generally increased in high fertility irrespective of variety (Table 1, Fig. 2a). Increase of tiller number in response to fertilizer addition was more in Monkhead compared with 92-46 (significant Variety × Fertility interaction, Table 1, Fig. 2a). Root biomass and stem&leaf biomass were greater in Monkhead (Table 1, Fig. 2b-c), but there was no significant difference in seed biomass between the two wheat varieties (Table 1, Fig. 2d). Fertilizer addition increased plant biomass in all plant components (Table 1, Fig. 2). Root and stem&leaf biomass responses to fertility differed between the two varieties (significant Variety × Fertility interaction, Table 1), with Monkhead showing more pronounced responses to high fertility compared with 92-46 (Fig. 2b-c). We did not detect significant interactions between variety and fertility for seed biomass (Table 1, Fig. 2d). There were no significant effects of partition treatments on tiller number or biomass, and we did not detect significant Variety × Partition interactions, Fertility × Partition interactions or Variety × Fertility × Partition interactions (Table 1).
Allometric relationships
We found significant linear relationships between whole plant biomass and reproductive or non-reproductive components across treatments (Table 2). In root-total relationships, the slope and intercept were similar between Monkhead and 92-46 at either fertility level (Table 2, Fig. 3a-b). Fertilizer addition did not affect the slope but lower the intercept for both varieties (Table 2, Fig. 3a-b). In (stem+leaf)-total relationships, the slope was similar between the two varieties whilst the intercept for Monkhead was greater than that of 92-46 at either fertility level (Table 2, Fig. 3c-d). Fertilizer addition did not affect the slope for both varieties and the intercept for 92-46, but increased the intercept for Monkhead (Table 2, Fig. 3c-d). In seed-total relationships, the slope for Monkhead was greater than that of 92-46 whilst the intercept was lower at either fertility level (Table 2, Fig. 3e-f). Fertilizer addition did not affect the slope for both varieties and the intercept for 92-46, but decreased the intercept for Monkhead (Table 2, Fig. 3e-f).
In all 24 allometic comparisons (both slopes and intercepts) between mesh partition and plastic partition, only 4 showed small differences in slope or intercepts, and all of them were in low fertility treatments (Table 3, Appendix 1 and 2 ). For Monkhead in low fertility treatments, the intercept in seed-total biomass regression was lower in mesh partition than in plastic partition, whilst in (stem+leaf)-total biomass regression was greater (Table 3, Appendix 1c and e). For 92-46 in low fertility treatments, the slope in root-total biomass regression was greater in mesh partition whilst the intercept was lower (Table 3, Appendix 1b).