Does crop genetic diversity support positive biodiversity effects under experimental drought?

Using barley as a model crop, and pot-based plant communities, we studied the interactive effects of barley cultivar diversity and drought stress on plant productivity and the response of agricultural weeds, fungal disease, and aphids. three barley cultivars which varied in their known susceptibility to aphids, and to the pathogens Blumeria graminis f.sp. hordei and Rhynchosporium commune, seven planting combinations: three monocultures, three 2-cultivar mixtures, and one 3-cultivar mixture.