Biomass and leaf area were measured at the beginning of the
experiment (day 0), at the end of the stress (18 DAT) and relief
period (day 31) in both 2009 and 2010. Biomass was determined on
each sampling date on 6 replicate plants per treatment (and source,
in 2010). For biomass determination, plants were cut at the root
flare and leaves, stem and roots were weighted separately. Leaves
were immediately scanned on a A-3 scanner to determine total leaf
area per plant, average leaf area and leaf number per plant. Image
processing was carried out with Image Tool 3.0 (University of
Texas, Health Science Center, San Antonio, Texas). To determine
dry weight, leaves, stem and roots were over dried at 70 C until
constant weight was reached (approx. 72 h). Leaf Mass per Area
(LMA, g DWm2) was calculated as the ratio between leaf dry mass
and leaf area. Leaf Relative Growth Rate (RGR, mg g1 d1) was
calculated as in Guidi et al. (2008). Root to shoot ratio was calculated
on a DWbases. Stem and root water content was calculated as
reported by Maes et al. (2009a).