Effects of inoculation with a Composite Arbuscular Mycorrhizal Inoculum on Plant Tolerance to Salt Induced Water Stress in Strawberry

Strawberry (Fragaria × ananassa Duch.) is an herbaceous biennial plant belonging to the Rosaceae family. The fruits are appreciated throughout the world because of their delicious taste and also for their high antioxidant content. Strawberry plant is considered particularly sensitive to drought and water stress. Water stress negatively influences the entire plant, causing possible drops in yield and can eventually cause plant mortality if left untreated. Salt induced water stress has generally a negative effect on plant growth and yield. Nowadays, different alternatives have been used to mitigate the effects due to salt stress, including inoculation of soil microorganisms such as arbuscular mycorrhizal fungi (AMF). These fungi have been shown to have a palliative effect on water stress damages. The AMF can constitute a positive recourse to plants with the presence of extra-matrix hyphae. The latter are finer than the plant roots, which facilitates the use of water-filled pores, otherwise inaccessible to the roots. The present study was carried out under greenhouse conditions with the aim of determining the effect of applying a composite mycorrhizal inoculum on strawberry plants stressed by drought. Three salinity levels were used (10 %, 25 % and 50 %) and the parameters measured were: mycorrhization status, root diameter, root length, salinity index, visual score and relative water content. The results showed that the salinity index, at the 50 % salinity level, was strongly correlated with root diameter and relative water content. Visual scores, for the three salt treatments, depended on mycorrhization status (yes/ no), root diameter, root length and relative water content. For the three salt treatments, the relative water content depended on the salinity index, root length and mycorrhization status (yes/ no). Based on the results obtained, the present study suggests a positive effect of inoculation with mycorrhizae on the salt stress tolerance of strawberries. Key words: Strawberry, Arbuscular mycorrhizal fungi, Salinity, Roots, Drought, Water stress