High morphological and physiological plasticity of wheat roots is conducive to higher competitive ability of wheat than maize in intercropping systems.

Background and aims: Few studies have addressed the effects of root physiological plasticity on interspecific interactions. The present study aimed to investigate the plasticity of wheat and maize roots and their responses to nitrogen (N) application rates and neighboring species in wheat/maize intercropping. Methods: The roots of wheat and maize were sampled three times by auger after about 90 days of co-growth in the intercropping treatment with five levels of N application and sole crops at one N application rate. Results: Intercropped wheat altered its root length density (RLD) and lateral root distribution with different N application regimes, while lateral root distribution of intercropped maize was less sensitive to N application regimes. In addition, wheat had a 54.5 % (38-69 days) −375 % (0-37 days) higher N uptake rate per unit root length (NURl) when intercropped with maize compared with sole cropping but intercropped maize had either 58.3 % lower (0-37 days) or similar NURl than did sole cropped maize at the same N application rate. Conclusions: Our findings suggest that the competitive ability of the plant species for underground resources is conducive to plasticities in RLD, lateral root distribution in response to soil N, and N uptake efficiency to neighboring species. [ABSTRACT FROM AUTHOR]