Plants
Tomato plants Solanum lycopersicum cv. Better Boy (BB) were grown
in cubic plastic pots (3.5” x 3.5” x 3.5”) filled with Metromix 400
potting mix (Griffin Greenhouse & Nursery Supplies, Tewksbury, MA, USA)
in a greenhouse at the Pennsylvania State University
(25 ± 2°C, 70% ± 10% R.H., 16L:
8D). Plants were fertilized at the one-leaf stage with Osmocote Plus
15-9-12 Fertilizer (ICL Speciality Fertilizers, Summerville, SC, USA).
Tomato plants at the four-leaf stage (roughly 4 weeks old) were used in
all experiments.
Plants were subjected to three salt treatments:
1. No salt (0 mM): 200 ml of a 0 mM salt solution (distilled water) is
added to the base of the plant.
2. Medium/intermediate salt (100 mM): 200 ml of a 100 mM salt solution
is added to the base of the plant.
3. High salt (200 mM): 200 ml of a 200 mM salt solution is added to the
base of the plant.
100 mM was chosen as an intermediate concentration and 200 mM as the
high concentration based on multiple studies (Foolad, 1996; Zhang and
Blumwald, 2001; Dombrowski, 2003; Sun et al. , 2010; Munns and
Gilliham, 2015; Forieri, Hildebrandt and Rostás, 2016).
Plants were watered with their designated salt solutions every day for
three days unless specified otherwise, following which they were used
for experiments on the third day. It is worth noting that at the end of
the three-day period, the soil salt concentration might be higher than
the supplied amount due to salt accumulation in the soil. By the end of
the three-day treatment, salt-treated plants looked visibly stressed,
dark green in colour, and showed retarded growth.