Uncovering corn adaptation to intercrop with bean by selecting for system yield in the intercrop environment
2004
O'Leary, N. | Smith, M.E.
Evaluation of genetic materials bred in monoculture can provide only limited information about the potential to improve crops for the intercrop environment. Selection in intercrop may be required to uncover the genetic variability associated with intercrop adaptation. Due to the expense and difficulty associated with selection in the intercrop environment, its use must be justified by the superiority of materials selected in it over materials selected in monoculture. The aim of this study was to compare the improvement of overall performance in corn-bean (Zea mays L.-Phaseolus vulgaris L.) intercrop that resulted from intercrop selection, with that which resulted from selection in monoculture. Three cycles of divergent recurrent selection were used to generate two sets of improved corn families: YM selected for corn yield in monoculture and YS selected for system yield (corn yield plus three times bean yield) in corn-bean intercrop. YS allowed significantly (P < 0.01) higher bean yield and had higher system yield than YM. YS was also significantly shorter (P < 0.05), less leafy (P < 0.001), and had a more erect canopy (P < 0.05) than YM. Selection for system yield in intercrop uncovered adaptation to the intercrop environment that was not matched by selection for corn yield in monoculture. This justifies the use of the intercrop breeding environment for improvement of productivity from corn-bean intercrops.
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