Can arbuscular mycorrhizae increase tomato production under the current climate change scenario?

In the Mediterranean region, tomato has high water and fertilization demands. Under the current climate change scenario, the situation will be exacerbated by prolonged droughts and higher temperatures while increasing CO2 concentration might represent an advantage to a C3 crop such as tomato. Previous researches indicated that the effect of drought can be mitigated in plants inoculated with mycorrhizal fungi. In this experiment, we evaluated the performances of mycorrhizal tomato in response to drought and elevated CO2 concentration in terms of net photosynthetic rate, transpiration, water use efficiency, chlorophyll fluorescence and biomass production. In. Mycorrhizal and non-mycorrhizal tomato plants were subjected to severe stress following a dry-down protocol under ambient and elevated CO2 concentration. A recovery period, in which irrigation was restored, followed the dry-down cycle. Plant height, stem diameter, leaf area, chlorophyll content and fluorescence parameters were measured on all plants during the experiment. Whole canopy transpiration and photosynthetic rate were measured every twelve minutes by an automated multi chamber system composed of twelve sampling chambers. Gas exchange measurements were used to calculate instantaneous water use efficiency. Several changes were observed in plant morphology and physiology in response to mycorrhization and elevated CO2. Mycorrhizal tomatoes were shorter and had larger stem diameter than the non-mycorrhizal ones. Moreover, mycorrhizal tomato showed increased water use efficiency, and increased ratio of variable to maximum chlorophyll fluorescence (Fv/Fm) and electron transport rate (ETR).