Integrated response of intercropped maize and potatoes to heterogeneous nutrients and crop neighbours

Abstract

Background and Aims In communities, plants often simultaneously interact with intra- and inter-specific neighbours and heterogeneous nutrients. How plants respond under these conditions and then affect the structure and function of communities remain important questions. Methods Maize (Zea mays L.) was intercropped with potatoes (Solanum tuberosum L.). In the field experiment, we applied fertilizer both homogeneously and heterogeneously under monocropping and intercropping conditions. The heterogeneous nutrient treatment in intercropping was designed with different fertilizer placements, at intraspecific and interspecific rows, respectively. In the pot experiment, crops were grown under both homogeneous and heterogeneous nitrogen conditions with single plant, intraspecific and interspecific competition. Shoot and root biomass and yield were measured to analyse crop performance. Results In the field experiment, the heterogeneous nitrogen, compared with the homogenous one, enhanced the performance of the intercropped crop. Importantly, this effect of heterogeneous nitrogen was greater when fertilizer was applied at interspecific rows, rather than at intraspecific rows. Moreover, in pot experiments, the root foraging precision of the two crops was increased by interspecific neighbours, but only that of potatoes was increased by intraspecific neighbours. Conclusions The integrated responses of plants to heterogeneous neighbours and nutrients depend on the position of nutrient-rich patches, which deepen our understanding of the function of plant diversity, and show that fertilizer placement within multi-cropping systems merits more attention. Moreover, the enhanced utilization of heterogeneous nitrogen could drive overyielding in multi-cropping systems.