Effect of Arbuscular Mycorrhizal Fungi on Tree Growth and Nutrient Uptake of Sclerocarya birrea under Water Stress, Salt Stress and Flooding

Abstract

A greenhouse experiment was conducted to determine the influence of arbuscular mycorrhizal (AM) fungus inoculation on water stress, salt stress and flooding tolerance of three subspecies of Scleocarya birrea (A. Rich.) Hochst. Gigaspora margarita Baker and Hall was used for the inoculation. All the three subspecies of S. birrea had high tolerance both to water stress and flooding even without G. margarita inoculation. All flooded seedlings developed lenticels and survived three months of flooding. Non-mycorrhizal seedlings of S. birrea subsp. multifoliolata survived even under electric conductivity of up to 7.1 dS·m⁻¹. Root colonization by G. margarita markedly improved tolerance of S. birrea seedlings to water stress, salt stress and flooding. In particular, S. birrea subsp. caffra under water stress and flooding conditions showed the highest response to inoculation. Mycorrhizal S. birrea subsp. multifoliolata recorded enhanced uptake of N, P, Ca and Mg at 7.1 dS·m⁻¹. These results demonstrate that even though S. birrea has natural tolerance to water stress, salt stress and flooding, AM fungus is very effective in strengthening the tolerance of S. birrea grown in arid and semi arid areas.