Abstract: To investigate the responses of wheat seedlings to kin recognition in a complex neighborhood composed by both kin and stranger individuals, we conducted an experiment with hydroponically growing two wheat cultivars exposed to root exudates which varied with three levels of relatedness (i.e. intra-cultivar, inter-cultivar and inter-species), and two levels of neighborhood complexity (i.e. all individuals from either the same level of relatedness or a mixture with half of them from intracultivar and the other half from inter-cultivar/specific). The results showed that both relatedness and neighborhood complexity significantly affected specific leaf area (SLA) and specific root length (SRL) of wheat seedlings, and they interactively affected SLA, total root length, SRL, and mean root diameter. These morphological trait values in the kinstranger-mixed neighborhood were either significantly higher/lower or unchanged, as compared to those in the pure kin neighborhood and pure stranger neighborhood. Furthermore, these kin recognition induced responses were cultivar-dependent. Our results suggest that the growth and competitive strategies of wheat in response to a relatedness-mixed neighborhood are not simply at the average status between pure kin and pure stranger neighborhoods.

Key words: wheat, kin recognition, neighborhood complexity, root exudate, specific leaf area, specific root length.