Whole plant transpiration (WPT) and growth analysis
WPT was determined by a gravimetric methodology (Daloso et al., 2016b).
Soil-filled pots without plants were used to estimate direct evaporation
from soil. The pots were irrigated with water at beginning of the night
in a daily basis, except at the days in which the water was withdrawn,
as indicated in the figures. The pots were weighed at predawn and at the
end of the days. The daily WPT (g H2O
d-1 plant-1) was obtained by the
difference between the two weights and by subtracting the evaporation.
WPT was further recorded between different time intervals of a daily
course. Leaves larger than 5 cm length were used to estimate leaf area
(LA) by a previously described model (Antunes et al., 2008, 2017). LA
was recorded in three different days of the experiments, whilst the days
in between LA was estimated by linear regression (r2> 0.98). The LA (cm2) was used to
calculate specific leaf area (cm2g-1 leaf dry weight (DW)) as well as to estimate WPT
per leaf area (g H2O d-1m-2). At the end of WPT experiments, it was determined
the total leaf number (> 5cm length), stem length and the
DW of leaf, stem and roots by drying it at 80 °C for seven days. These
parameters were used to determined total dry biomass (leaf + stem +
roots), harvest index (leaf /total biomass), shoot DW (leaf + stem),
shoot/root (g g-1), leaves/root (g
g-1) and plant leaf area/roots (cm2g-1). The relative growth rate (RGR, g
g-1 day-1) was obtained by the
equation: RGR = ln (final weight) – ln (initial weight)/final day –
initial day following previous study (Hoffmann and Poorter 2002), in
which the initial DW of leaf and total biomass were estimated by
regression using leaf area measurements (Figure S1).