Sorghum genetic variability for adaptation to intercropping with cowpea in Sudano-Sahelian conditions

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Résumé

Context: Intercropping is a crop diversification strategy that enhances the sustainability of agricultural production
systems by delivering a range of ecosystem services. It minimizes the risk of crop failure and increases landuse
efficiency. However, limited knowledge exists about the varieties and traits that can enhance the performance
of cereal/legume intercropping systems.
Objective: This study aims to explore the effect of sorghum genetic variability on intercropping performance and
identify the genetic traits of sorghum that most influence the outcomes of intercropping.
Method: Thirty sorghum varieties, representing a broad range of diversity, were grown both in pure stands and as
intercrops, with a single cowpea variety used as a tester. The experiment was conducted in 2020 and 2021 in
Burkina Faso, using a split-plot design with three replications each year. Genotype rankings were established for
both cropping systems, and genotype × cropping system interactions were evaluated.
Results: The total grain yield of the intercrop (sorghum + cowpea) was not significantly different from that of
sorghum grown as a pure crop (2000 kg ha􀀀 1 and 2051 kg ha􀀀 1, respectively). However, the intercrop produced
more grain protein (290 kg ha􀀀 1) than the pure crop (217 kg ha􀀀 1). Significant genotypic variability was
observed for most traits, with few instances of significant genotype × cropping system interactions. No significant
effect of sorghum genotypes on cowpea grain yield was found, nor was there a negative correlation between
cowpea and sorghum grain yields in the intercrop. In 2021, competition was observed through a negative correlation
between cowpea grain yield and sorghum biomass, as well as a positive correlation with sorghum
harvest index. However, this competition was not for light, but for water.
Conclusions: The choice of sorghum varieties for intercropping in our conditions depends mainly on the farmer’s
objectives regarding grain quality and production, avoiding varieties with high biomass and low harvest index.
Further research should focus on the effect of cowpea genetic variability on the performance of sorghum-cowpea
intercropping.

Mots-clés

Row intercropping, Substitutive design, Sorghum bicolor, Vigna unguiculata, Genetic variability, Low input