Arbuscular mycorrhizal fungi improve growth and mineral uptake of olive tree under gypsum substrate

In Tunisian dry land soils, the gypsum is ubiquitous with water scarcity and represents a major limitation for olive and several other fruit tree cultures. However, the effect of gypsum on this species is little understood. One-year old olive plants cv. “Chemlali”, which were obtained from semi hardwood cuttings, were inoculated in a nursery with an endomycorrhizae (Glomus intraradices) and they were grown in a substrate containing different proportions of gypsum. The mycorrhizae inoculation played an important role in the attenuation of the effect of sulphates contained in gypsum substrate. In fact, the obtained results showed that growth, shoot elongation and leaf area were affected by the presence of mycorrhizae. A significant growth reduction of plants was obtained with increasing gypsum rate, but this reduction was less pronounced in mycorrhizal plants. Besides, the leaves relative water content decreased as the gypsum content increased. Interestingly, G. intraradices produced an important water supply by increasing leaves relative water content in mycorrhizal plants. Calcium and phosphorus contents were significantly higher in mycorrhizal plants, which were mainly accumulated in leaves. Sulphate was accumulated in the plant roots and G. intraradices was able to attenuate such effect in mycorrhizal plants.