Intercropping with two native woody shrubs improves water status and development of interplanted groundnut and pearl millet in the Sahel

Abstract

Aims: To investigate the physiological responses of groundnut (Arachis hypogea) and pearl millet (Penisetum glaucum) that were intercropped with the native evergreen woody shrubs Piliostigma reticulatum (D.C.) Hochst and Guiera senegalensis J.F. Gmel compared to control crops throughout two growing seasons at two sites with contrasting climate and soil types in Senegal. Methods: Shrubs grown in groundnut and millet fields at higher than native density were coppiced annually with aboveground biomass returned to the soil and no additional fertilizer. Crop leaf area index (LAI), handheld normalized difference vegetation index (NDVI), leaf water potential, and soil moisture and temperature were monitored in 2012–2013. Results: At the drier site, the presence of shrubs reduced soil temperature at 5 cm depth by up to 5 °C during early crop growth. Shrub presence increased LAI by up to 266%, NDVI by up to 217% and increased groundnut leaf water potential throughout the day at the wetter site. Shrub effects on crop physiology were stronger overall at the drier site. Conclusions: These results improve the understanding of how this unique agroforestry system alters the growing environment and the physiological response of associated crops throughout the season.