Influence of arbuscular mycorrhiza on photosynthesis and water status of Populus cathayana Rehder males and females under salt stress

The influence of arbuscular mycorrhizal fungi (AMF) Rhizophagus irregularis on biomass, root morphological characteristics, water status, gas exchange and ion contents of Populus cathayana Rehder males and females under salt stress was studied in a greenhouse experiment. Sex had no influence on AMF colonization. Salt stress decreased the biomass, modified root characteristics, inhibited photosynthesis, relative water content (RWC), while increased the water use efficiency (WUEi), the ratio of root/shoot (RSR) and salt ion contents within the plants. Males and females differed in response to the salt stress and AMF inoculation. AMF inoculation increased the biomass of root, the biomass of shoot, and decreased RSR, especially in males. The root length, root volume (RV), root surface area, and root tip numbers (RTN) were increased with AMF inoculation in males, while RV and RTN were decreased with AMF inoculation in females. AMF had positive effects on RWC and WUEi in both sexes. Mycorrhizal cuttings also had higher gas exchange capacity, lower salt ion contents than non-mycorrhizal cuttings. The principal component analysis showed that males exhibited a better salt tolerance than females, and AMF inoculation had positive effects on both sexes, especially in males.