Intercropping chickpea with a competitive service plant and mowing the inter-rows controls weeds and ascochyta blight while mitigating interspecific competition

Chickpea ( Cicer arietinum L.) is a promising crop for adapting to climate change and reducing the reliance of cropping systems on synthetic N fertilizers. However, its yield is highly variable, mainly due to weed competition and ascochyta blight ( Ascochyta rabiei ). Hence, this study investigated the effects of intercropping chickpea with a mowed service plant to control both weeds and ascochyta blight, while mitigating competition to minimise yield reductions. In a two-year field experiment in Western France, chickpea was grown as sole crop and intercropped with four single service plants (Egyptian clover, faba bean, oat, and Sudan grass) in alternate rows. These species were chosen for their contrasted traits, allowing to create different levels of interspecific competition. Chickpea’s inter-rows were either mowed at the beginning of flowering or left without mechanical regulation. Introducing oat decreased weed biomass in both years. Under high weed and disease pressures, adding unmowed oat reduced both weed biomass and ascochyta blight severity by 66% and 56% compared to the unmowed sole chickpea, respectively. No differences were found between the sole chickpea and the other intercrops. Unlike the other species, oat had a high biomass production early in the crop cycle, which partly explains its weed-suppression effect. However, adding oat reduced chickpea grain yield in 2023 by 72%, although mowing limited this reduction to 48%. This study highlights that intercropping chickpea with a mowed competitive service plant that generates an aerated canopy, like oat, can help to control both weeds and ascochyta blight, while mitigating interspecific competition. • The effects of intercropping and mowing on weed and disease control were studied • Mowing improved weed and disease control in most treatments at high biotic pressures • Mowing the inter-rows increased grain and biomass production by chickpea • High weed biomass exacerbated ascochyta blight symptoms • Oat improved weed and disease control but can highly decrease chickpea grain yield