An open field trial was established to evaluate production, carotenoids, ascorbic acid, and soluble solids of processing tomato inoculated with arbuscular mycorrhizal fungi either at sowing, and reinoculated at transplanting compared to non-treated plants under different soil moisture conditions. Depending on plant water requirement, all treatments induced to three levels of water supply: Full water supply, half water supply, and no water supply by adjusting the water amount. Regardless of mycorrhizal inoculation time and dosage, plants under no water supply conditions faced severe stress and showed no enhancement in growth, yield, and water use efficiency. Mycorrhizal re-inoculation significantly increased the marketable fruit yield, the total biomass, the water use efficiency, and leaf water potential under water shortage conditions in half water supply compared to at sowing inoculated mycorrhizal plants, and non-treated plants as well, suggesting that field mycorrhizal re-inoculation enhances colonized plant water stress avoidance. A strong negative correlation was observed between yield and soluble solid content. Concisely, mycorrhizal re-inoculation was more effective than inoculation at sowing.

In a field experiment, processing tomato plants inoculated with arbuscular mycorrhizae (AM) and non-inoculated (Control) were supplied with three levels of watering. The AM inoculation significantly increased tomato root colonization regardless of the water supply levels. Under water deficit conditions, AM inoculation significantly increased the biomass production (from 1,189 to 2,062 g plant-1). AM inoculation increased the phosphorus uptake in water deficit supply (from 0.5 to 1.3 g plant-1) and in optimum water supply (from 0.3 to 0.6 g plant-1). Photosynthesis was not affected by irrigation, but mycorrhizal inoculation enhanced the efficiency of photosystem II at all water levels. Inoculated plants accumulated less proline, potassium, and magnesium in shoots in response to water stress. Less organic and inorganic solutes in shoots of inoculated plants were accompanied by higher water use efficiency, better stomatal conductance, and higher leaf water potential. In conclusion, AM inoculation enabled host plants to alleviate moderate water stress, modulating the physiological status of the plants for better water exploitation.

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