Supplement of a commercial mycorrhizal product to improve the survival and ecophysiological performance of olive trees in an Arid region

Abstract

Rainfed olive groves in arid Tunisia face severe water scarcity and a low abundance of native arbuscular mycorrhizal fungi (AMF). We investigated if a supplement of commercial AMF-product at transplantation would improve olive plant survival and ecophysiological performance in an arid region. The commercial AMF product was added to two olive tree cultivars, ‘Meski’ and ‘Zarrazi’. There was an increase in the mycorrhizal intensity in the roots of ‘Meski’. Mycorrhizal symbiosis seems to have improved the survival of ‘Meski’ and the growth rate of ‘Zarrazi’. Plant water status and gas exchanges were enhanced in ‘Meski’. Mycorrhization helped maintain a higher photosynthetic assimilation rate and stomatal conductance in ‘Zarrazi’. AMF-symbiosis exhibited an inter-cultivar difference in the enhancement of the ecophysiological performance of olive trees under aridity. It also improved pre-existent indigenous defense strategies. It reinforced the avoidance strategy of ‘Meski’ but strengthened the tolerance strategy of ‘Zarrazi’.

Keywords

• drought
• gas exchanges
• growth
• indigenous strategy
• inter-cultivar variability