This study was undertaken to explore the relation between auto-, allo- and nil-competition using a long established pure line cultivar of bread wheat, where genes controlling yielding and competing ability co-exist and co-interact. The investigation lasted three growing periods, the first two with trials grown at nilcompetition (100 cm), and the third with trials grown at the three conditions of competition. In the first growing period, divergent single plant honeycomb selection for high and low yield was applied in the cultivar Siete Cerros, to continue in the second growing period with divergent line honeycomb selection. In the third growing period, top and bottom lines selected under nil-competition were compared with the mother variety Siete Cerros under auto-, allo- and nil-competition.
Correlation coefficient estimates between auto-, allo- and nil-competition demonstrated that auto-competition and nil-competition are correlated positively interse and negatively with allo-competition. In general, the results suggest that yielding and competing ability are correlated negatively.
The implications of the findings are discussed in relation to the possibility of (1) selecting for heritable high yield on a single plant basis, (2) avoiding biased results due to interplot competition, (3) substituting cultivar degeneration for cultivar improvement.
Triticum aestivumbread wheat single plant selection for yield inter-genotypic competition interplot competition cultivar degeneration