The yield and phosphorus content of maize intercropped with faba bean are enhanced by belowground interspecies interactions at low phosphorus input and by aboveground interactions at high phosphorus input

Aims

Many studies used physical barriers to separate the roots of different species to dissect the contributions of above- and below-ground interspecies interactions to yield and phosphorus (P) uptake. However, the extent to which the presence of barriers itself alters these contributions remains unknown.

Methods

The field study, conducted in 2010 and 2011, used root barriers in both sole cropped and intercropped maize at two P levels. We examined the contributions of interspecies interactions to yield, biomass and P content in all treatments. The field experiment followed a split plot design with two P levels (P0: 0 kg ha⁻¹, and P35: 35 kg P ha⁻¹), three cropping systems (sole maize, sole faba bean and maize/faba bean intercropping), and two types of root separation (solid barrier -SB- and no barrier -NB-).

Results

The presence of a solid barrier negatively impacted the yield of sole maize, reducing it by 26% in 2010 and by 56% in 2011 compared with conditions without a barrier, indicating that the barrier itself adversely affected the growth of sole maize. Notwithstanding the barrier's influence, the belowground interspecies interactions were the primary contributors to the increased grain yield and P content observed in maize/faba bean intercropping under the P0 treatment. In contrast, aboveground interactions were more significant in enhancing the performance of the intercropping system at the P35 treatment.

Conclusions

Phosphorus fertilization diminished the effects of belowground interspecies interactions while amplifying the impact of aboveground interspecies interaction on the advantages of intercropping, regarding grain yield and P uptake.