Speaker
Description
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Introduction. In the context of global challenges such as climate change, declining soil fertility, and the aging of cocoa orchards, the sustainable production of cocoa in West Africa is under significant threat (Ameyaw et al., 2018). As the region contributes over 70% to the world's cocoa supply, these challenges call for a profound reevaluation of conventional agronomic practices. This requires looking into innovative sustainable cultivation strategies that can bolster crop resilience, enhance soil health, and ensure economic viability for cocoa farmers. Arbuscular mycorrhizal fungi (AMF), which form symbiotic relationships with the roots of cocoa plants, offer a promising mechanism for achieving these goals. The symbiosis between cocoa plants and AMF can play a pivotal role in enhancing nutrient uptake, improving water retention, and increasing resistance to pathogens and environmental stressors (Leye et al., 2015). Given the diverse and complex ecosystems within which cocoa is cultivated, understanding the dynamics of AMF within cocoa agroforestry systems is crucial for developing sustainable agricultural practices.
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Materials and methods. This study adopts an innovative methodological approach to assess the impact of agricultural practices on arbuscular mycorrhizal fungi (AMF) communities associated with cocoa plants. Composite soil samples were collected from 110 cocoa agroforestry plantations across the entire cocoa production zone in Côte d'Ivoire. The collected samples were analyzed to determine soil physicochemical properties and AMF spore density. Spore extraction was performed using the wet sieving method as described by Gerdemann and Nicolson (1960). After extraction, the spores underwent meticulous counting and detailed morphological analysis.
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Results. The analysis of the total density of the spore after wet sieving of soil samples from 110 different cocoa plantations revealed significant variations in spore density between the sampling sites (p<0.05). This variability extends to the species richness of mycorrhizal fungi, which was observed to differ among cocoa plantations. Notably, the genus Glomus, Acaulospora, and Gigaspora emerged as the most frequently encountered across the sites. Furthermore, soil pH was found to directly influence mycorrhizal spore abundance, with a notable correlation identified. Specifically, slightly acidic pH conditions (pH <7) were found to adversely impact spore density, suggesting a sensible balance between soil acidity and the thriving of mycorrhizal fungi populations.
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Discussion. In alignment with previous studies, the abundance and diversity of the natural communities of arbuscular mycorrhizal fungi are largely influenced by the soil properties in cocoa-based agroforestry systems. The genus Glomus, Acaulospora, and Gigaspora have been identified as generalist symbionts prevalent in numerous rhizospheres highlighting the significant role of soil physicochemical properties on the diversity and abundance of mycorrhizal spores (Pontes et al., 2024). Notably, low soil pH is shown to adversely affect spore density (Droh et al., 2022), underscoring the intricate relationship between soil health and the symbiotic interaction with cocoa plants. The presence of Acaulospora across different sites illustrates the potential of specific AMF species in enhancing plant health and soil fertility, thereby advocating for the integration of AMF-based strategies into cocoa agroforestry management.
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References
Ameyaw L.K., Ettl G.J., Leissle K., and Anim-Kwapong G.J. (2018), Cocoa and climate change : insights from smallholder cocoa producers in Ghana regarding challenges in implementing climate change mitigation strategies. Forests, 9(12), 742
Droh G., Djezou K.M., Kouassi K.B.A., Kouassi A.B. and Tiecoura K. (2022) Diversity of Arbuscular Mycorrhizal Fungi Spores in Maize (Zea mays L.) Plantations in Côte d'Ivoire. American Journal of Agriculture and Forestry. 10(5), 170-180.
Gerdemann J.W. and Nicolson T.H. (1963), Spores of mycorrhizal Endogone species extracted from soil by wet sieving and decanting. Transactions of the British Mycological Society, 46(2), 235-244
Leye E. H. M., Ndiaye M., Diouf M., Diop T. (2015). Etude comparative de l’effet de souches de champignons mycorhiziens arbusculaires sur la croissance et la nutrition minérale du sésame cultivé au Sénégal. African Crop Science Journal, 23(3), 211-219.
Pontes J.S., Oehl F., Pereira C.D., Machado C.T.T., Coyne D., Silva D.K.A., Maia L.C. (2024). Heterogeneity in Arbuscular Mycorrhizal Fungi and Plant Communities of the Brazilian Cerrado, Transitional Areas toward the Caatinga, and the Atlantic Forest. Microbial Ecology 87:29
| Keywords | Arbuscular mycorrhizal fungi; cocoa production; climate change adaptation; soil health; sustainable agriculture |
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