Arbuscular mycorrhiza influences carbon-use efficiency and grain yield of wheat grown under pre- and post-anthesis salinity stress.

Soil salinity severely affects and constrains crop production worldwide. Salinity causes osmotic and ionic stress, inhibiting gas exchange and photosynthesis, ultimately impairing plant growth and development. Arbuscular mycorrhiza (AM) have been shown to maintain light- and carbon use-efficiency under stress, possibly providing a tool to improve salinity tolerance of the host plants. Thus, it was hypothesised that AM will contribute to improved growth and yield under stress conditions. Wheat plants (Triticum aestivum L.) were grown with (AMF+) or without (AMF-) AM fungal inoculation. Plants were subjected to salinity stress (200 mM NaCl) either at pre, post-anthesis, or at both stages. Growth and yield components, leaf chlorophyll content as well as gas exchange parameters and AMF colonisation were analysed. AM plants exhibited a higher rate of net photosynthesis (Pn ) and stomatal conductance (gs ), and lower intrinsic water use efficiency (WUEi ). Furthermore, AM wheat plants subjected to salinity stress at both pre-anthesis and post-anthesis maintained higher grain yield than non-AM salinity-stressed plants. These results suggest that AMF inoculation mitigates the negative effects of salinity stress by influencing carbon-use efficiency and maintaining higher grain yield under stress.