Root functional traits drive the overyielding in maize/legume intercropping systems

Hao Yang, Hua-Sen Xu, Wei-Ping Zhang, Zhao-Xin Li, Hong-Xia Fan, Hans Lambers, Long Li

This is a plain language summary of a Functional Ecology research article that can be found here.

Intercropping is an effective practice for eco-friendly production and sustainable agricultural development. Intercropping promotes the efficient use of resources in agroecosystems, including nutrients, water and light. Root systems often play an important role in plant performance and affect a range of ecosystem functions. Linking root traits and intercropping effects may help to reveal the ecological principles underlying overyielding (i.e. better performance of mixtures than monocultures) in intercropping. We conducted a field experiment with four nitrogen-application rates, combining five cropping systems (monoculture maize and the legumes peanut and soybean, plus maize/soybean and maize/peanut intercropping), and measured root traits to explore mechanisms of overyielding from the perspective of belowground interactions between maize and legumes (peanut or soybean).

The aerial photograph of the experimental layout (credit: Hao Yang)

We show that, in intercropping, maize had a greater root morphological plasticity than the legumes in response to neighbors and nitrogen application, which strengthened overyielding of the dominant species. A positive complementarity occurred without nitrogen application, consistent with the ‘stress-gradient hypothesis’, which predicts that complementarity effects or the strength of facilitative interactions are greater in more stressful environments. Our results show that complementarity was closely associated with root traits such as mean root depth and root length. The physiological plasticity of root traits may also be important to interspecific complementarity in stressful environments. Therefore, a desirable combination of two crops with different morphological and physiological root plasticity may enhance the advantages of intercropping.


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