Agroforestry improves the benefits of cereal-legume intercropping under drought

Barkaoui Karim. 2022. Agroforestry improves the benefits of cereal-legume intercropping under drought. In : Proceedings of the 5th World Congress on Agroforestry: Transitioning to a Viable World. Oliver A. (ed.), Bissonnette J.F. (ed.), Cogliastro A. (ed.), Gauthier C (ed.), Gélinas N. (ed.), Laroche G. (ed.). Université de Laval. Québec : Université de Laval, Résumé, p. 336. World Congress on Agroforestry 2022. 5, Québec, Canada, 17 Juillet 2022/20 Juillet 2022.

Résumé : The benefits of cereal-legume intercropping are promising under non-limiting water conditions due to the high resource-use complementarity between the species. The positive effects are interesting to improve yields in zero-input organic agriculture. However, the balance of plant-plant interactions may shift depending on the environmental conditions. Cereals and legumes may compete more intensively for water and nutrients under drought, making yield decline in intercropping. In this study, I asked whether agroforestry could recover or boost the benefits of cereal-legume intercropping in drought-prone areas. I hypothesized that shading trees create beneficial conditions that could alleviate the negative impacts of drought on plant-plant interactions. To test the hypothesis, I conducted a two-year field trial on two different sites with contrasting levels of aridity during the growing season, respectively in the North (France, 337 mm, the 'wet site') and the South (Morocco, 150 mm, the 'dry site') Mediterranean. I compared two cereal (barley and durum wheat) and legume (faba bean and chickpea) species in monoculture versus in mixture, in full conditions versus in agroforestry with olive trees following a split-plot design. The trials were managed with zero-input organic practices to better detect the shift in plant-plant interactions between sites and mixtures. I found that drought negatively impacted biomass production but not yields across sites. In general, cereal-legume mixtures were effective (+ 45 % of yield), especially at the 'dry site'. Cereals (+ 37 %) more than legumes (+ 8 %) benefited from intercropping. Despite reduced crop yields (- 60 % on average), agroforestry improved (wheat-legume mixtures) or at least had no effect (barley-legume mixtures) at the dry site, while it negatively impacted all the cereal-legume mixtures at the 'wet site' (- 20 %). The results show that trees can positively modify the outcome of plant-plant interactions underlying the benefits of intercropping under increasing drought.

Mots-clés libres : Olive, Mediterranean, Relative yield, Stress-gradient hypothesis, Plant-plant Interactions

Auteurs et affiliations

• Barkaoui Karim, CIRAD-PERSYST-UMR ABSys (FRA) ORCID: 0000-0002-5787-3748

Source : Cirad-Agritrop (https://agritrop.cirad.fr/603577/)

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