On a per-transplant basis, lettuce was more competitive than
alyssum because lettuce DM was only 25% less in the highest density
intercropping treatment (L100 + A100) than in L100, whereas
alyssum DM was 46% less in L100 + A100 than in A100 (Fig. 2A
and B). Averaged across years, alyssum transplants grown alone
on beds (A100) contained 32% less DM than lettuce transplants
grown alone on beds (L100) (Fig. 3B). This demonstrates that lettuce
was more productive than alyssum in terms of shoot DM at
the standard planting density for lettuce. Previous studies found
that shoot biomass is a good predictor of competitive ability