Abstract:
Species and cultivar combinations have been relatively well studied, though little
is known about the influence of spatial arrangement on agricultural or native plant
mixtures. The effect of spatial pattern on mixtures was explored in three experiments. In
the first two, agricultural and native plants were planted in two-way mixtures that
included combinations of cultivars, species, genera, or functional groups. Each
combination was arranged as a random mixture within rows, alternating rows of different
genotypes or species, and as alternating pairs of rows. Biomass was determined for each
mixture component and compared to monoculture controls. In the third experiment, two
wheat cultivars were planted in seven treatments in the 2000-2001 winter wheat season
and three cultivars were planted in 18 treatments in the 2001-2002 season. One cultivar
was always planted at full rate, and a second cultivar was added at 1/4 rate, either
randomly mixed, or between rows of the other cultivar. Performance was measured in
terms of seed yield. The specific species or cultivar combination had the most consistent
influence on aboveground biomass or seed yield, while the effect of spatial arrangement
was significant in few treatments.
