Plant material and growth conditions
Tomato seeds (Solanum lycopersicum , cv Castelmart) were surface
sterilized in 4% sodium hypochlorite, rinsed thoroughly with sterile
water and germinated for 3 days on moistened filter paper at 25°C in
darkness. Subsequently, seedlings were transferred into 3 L plastic
containers and grown hydroponically with water during the first week and
with 0.5x Long Ashton nutrient solution (Hewitt, 1966) until the end of
the experiment. The nutrient solution was replaced by fresh solution
once a week.