The experimental design was a randomized complete block
with 4 blocks of eight treatments including lettuce monoculture
(L100) and seven strip intercropping treatments. Each block was
10.2 m wide (10 beds) and 4.5 m (2008) or 10 m (2009) long. The
experimental unit for each treatment was a single bed with two
plant rows. In addition to the eight treatments of interest, each
block contained two additional lettuce–alyssum intercropping
treatments that were not of interest and were excluded from the
analysis. The furrow between adjacent beds was considered an
adequate buffer area to prevent below or above ground competition
between adjacent treatments because the furrow was cultivated
15–18 d after transplanting (DAT) and remained dry
throughout the remainder of the crop, and because the canopies
of the plants on adjacent beds did not overlap during the study.