Physiological analysis
After measuring the dry weight of the upper part and roots of plants
that were treated for 15 days (Figure 1A ), a decrease in the
upper part dry weight (DW) was observed in salinity plus B-deprivation
(Comb (-)) treatment compared to control plants. The salinity (NaCl) and
Comb (-) treatments were lower and statistically different upper part
values from plants treated with B excess (B (+)), which had the highest
upper part total dry mass. Additionally, NaCl and Comb (-) treated
plants presented lower root DW than the control plants. The analysis of
relative water content showed no differences of any of the treatments
with the control plants. However, while B (-) and B (+) showed no
significant differences, when they were combined with salinity, Comb (-)
were significantly lower than Comb (+). The Leaf per Mass Area (LMA)
data (Figure 1B ) showed that only the salinity leaves were
significantly different from the control plants, providing higher
values.
We analyzed stomatal conductance (Figure 2 ) every 3-4 days from
the beginning to the end of the experiment. The control and B (-) plants
showed the highest stomatal conductance that were maintained during all
the time of the experiment. Plants treated with B (+) maintained similar
values than control until the 3rd day of treatment
showing from that day a significant decrease that remain stable from
10th to 13th day of treatment.
Salinity (NaCl), Comb (-), and Comb (+) treatments had the lowest
stomatal conductance that decreased at first day of treatment, about
half that of the control plants, being the lowest those plants treated
with NaCl. During the experiment, the stomatal conductance of B (+)
treated plants reached similar stomatal conductance to the
salinity-related treatments at 10th day of treatment.
The mineral analysis of leaves (Figure 3A ) showed a clear
division between salinity-related treatments and non-salinity treatments
along the horizontal axis and between B (-) and B (+) treatments
(including Comb (-) and Comb (+) respectively) along the vertical axis,
as summarized by a Principal Component Analysis (PCA). The interactions
between Na and K, as well as between B and Mn, were negative. However,
Cu and Zn demonstrated a positive interaction with NaCl and Comb (-)
treatments, but a negative interaction with treatments related to excess
B (B (+) and Comb (+)). Figure 3B-D illustrates individual
plots of B, Na, and K concentrations as mass per DW represented as box
plots. The control plants had around 50 mg mg kg-1 DW
of B, while NaCl, B (-), and Comb (-) treatments had lower
concentrations, being Comb (-) leaves the one that presented the lowest
concentration of B among all treated plants with around 10 mg
kg-1 DW. Alternatively, B (+) treated plants had the
highest amount of B at 109 mg kg-1 DW, doubling the
control B concentration, followed by Comb (+) at 87 mg
kg-1 DW. The three salinity-related treatments (NaCl
and the two combinations) had 3.0-3.5 g of Na per 100 g DW, while the
rest of the plants had marginal concentrations. In contrast, K levels
were lower these salinity treatments, along with B (-), which also had a
reduction in K presence compared to control plant leaves, but it was
still higher than the salinity treatments.