Extremely low frequency non-uniform magnetic fields induce changes in water relations, photosynthesis and tomato plant growth.

To elucidate the effects during the vegetative growth of pre-sowing magnetic treatments on water relations, photosynthesis and plant growth in tomato (Vyta) plants under greenhouse conditions. Tomato seeds were exposed to full-wave rectified sinusoidal non-uniform magnetic fields (MFs) induced by an electromagnet at 120 mT (rms) for 10 min and at 80 mT (rms) for 5 min. Non-treated seeds were used as controls. Plants were grown in polystyrene trays and water relations, photosynthesis and plant growth were measured. Plants from magnetically treated seeds maintained better leaf water status in terms of increases in leaf water potential, leaf osmotic potential, leaf turgor potential and relative water content, and decreases in stomatal conductance and transpiration rate. Net photosynthesis rate, chlorophyll a, chlorophyll b, carotenoids and total chlorophyll contents increase in plants from magnetically exposed seeds compared to controls. The MF treatments lead to a notable increase in root length, plant height, root and shoot dry mass, leaf area per plant, and root and shoot relative growth rates. Application of full-wave rectified sinusoidal non-uniform MF as a pre-sowing treatment has the potential to improve tomato plant vegetative growth through the enhancement of water relations and photosynthesis.