Biomass accumulation and physiological responses of tomato plants to magnetically-treated water in hydroponic conditions

Magnetically-treated water (MTW) has been reported to enhance biomass accumulation in plants. However, the underlying mechanisms are not fully understood, and the existing reports only deal with soil-grown plants. Thus, the purpose of this experiment was to assess whether or not MTW affects main physiological processes (gas exchange, biomass accumulation and water potential) in tomato plants whose water supply was only MTW. Two experiments were done in hydroponic semi-controlled conditions, consisting of a loop system with permanent recirculation of water through a non-uniform magnet. The plants grown under MTW showed a significant increase in chlorophyll content, photosynthesis and transpiration at high light irradiances, although the increase in stomatal conductance was less significant. MTW also increased fruit fresh biomass, number of fruits and root dry biomass in 61.7 %, 85.3 % and 30.3 % respectively, but this was only achieved at natural sunlight conditions. Moreover, treated plants showed higher root hydraulic conductance and leaf water potential, which is thought to be related with a lower surface tension of MTW, an effect that is consistent with previous studies. The higher biomass accumulation in tomato plants under MTW is likely explained because of a faster water transport from the roots to the leaves via xylem, which in turn increases H2O efflux and CO2 assimilation in the leaves, thanks to a higher stomatal conductance.