Arbuscular mycorrhizal fungal inoculation and exogenous phosphate fertilisation in mitigating NaCl induced salinity stress: Effects on growth parameters, mineral balance, and biochemical metabolites in Taro (Colocasia esculenta L. Schott Var. Ibo Coco)

Abstract

Soil salinity is a major constraint to agricultural productivity in several regions of Cameroon. This study evaluates the impact of phosphate fertilisation and mycorrhizal inoculation on the growth, mineral nutrition, and biochemical constituents of taro (Colocasia esculenta var. Ibo coco) under salt stress. The experiment, conducted in a greenhouse for five weeks, used a completely randomised block design. Plants were subjected to different NaCl doses (0, 50, 100, and 200 mM), combined with phosphorus inputs (0.1, 0.5, and 1 g) and two mycorrhizal consortia (Gigaspora margarita + Acaulospora tuberculata (Bio1) and Scutellospora gregaria (Bio2)). The results demonstrate that NaCl induced a significant inhibition of growth (p < 0.001) and ionic imbalance (Na+ , K+ , P). An accumulation of soluble proteins and total phenols was observed from 100 mM NaCl, reflecting a response to osmotic stress. Phosphate input exerted a protective effect by regulating ionic distribution and attenuating growth inhibition. However, a decrease in biomass and chlorophyll only appeared at the 200 mM NaCl threshold with 1 g of phosphate. Finally, mycorrhizal inoculation, particularly with the Bio1+2 consortium associated with phosphate, neutralised the deleterious effects of salinity, improving vegetative vigour and photosynthetic efficiency. In conclusion, this synergy constitutes a sustainable biotechnological strategy to strengthen the resilience and yield of taro in saline areas.