Neighbour effects in the genus Avena. 3. A diallel approach.
Results are reported from a mechanical diallel experiment with Avena fatua, A. ludoviciana, A. strigosa and oats cv. Blenda. Relative yield totals based on tiller number were close to unity whereas those based on panicle number were >1. In mixtures containing A. strigosa the total weights of panicles equalled or exceeded those in monoculture of the more productive component. On the deepest soil the average relative yield total for all mixtures was significantly greater than unity for panicles but not for straw weight. Compensating effects in later stem extension were most marked on the shallowest soil; this was considered to support the hypothesis that competition for soil factors began there first. The particularly high panicle weight relative yield totals for A. strigosa + A. fatua suggested that these species used the plot resources in different ways (root stratification). The deeper soil probably allowed complementary exploitation of soil factors during grain filling. [For Part 2 see FCA 27, 5482]