Predicting intercrop competition, facilitation, and productivity from simple functional traits

Summary

This field study investigated whether two simple functional traits—plant height and specific leaf area—could predict intercrop productivity and the mechanisms (facilitation vs. competition) underlying overyielding. Conducted across three African sites over two years, the research found that whilst height and SLA together explained less than a third of variation in intercrop land equivalence ratios, site conditions appeared to interact substantially with these traits to determine yield outcomes. The findings suggest that functional traits alone have limited predictive power for intercrop performance without accounting for local environmental context.

UK applicability

The study was conducted in Kenya and Nigeria under tropical and subtropical conditions, which limits direct applicability to UK temperate farming systems. However, the methodological approach of using functional traits to screen intercrop combinations could be adapted for UK crop choices and growing conditions, subject to local validation.

Key measures

Plant vegetative height; specific leaf area (SLA); intercrop grain yield; land equivalence ratio (LER); biomass LER; inter- versus intraspecific competition strength; facilitation effects

Outcomes reported

The study measured intercrop grain and biomass yields, land equivalence ratios (LER), and the strength of facilitation and competition effects in relation to plant height and specific leaf area (SLA). Intercrop productivity was evaluated across monocrop, intercrop, and single plant treatments at three field sites in Kenya and Nigeria.

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