2.2.2. Plant sampling and analysis
Plants were harvested after 71 days, just before booting stage,
by cutting the shoots approximately one centimetre above the
soil surface. Plant samples were washed with distilled water and
oven dried at 70 ◦C until a constant weight was reached. Roots
were separated from soil by the following procedure: rinsing with
distilled water, followed by a second rinsing with 0.02 M ethylenediaminetetraacetic
(EDTA) solution and three other rinsing steps
with distilled water, before oven drying at 80 ◦C until a constant
weight was reached. Total dry weights of the roots and shoots were
measured. All shoot and root samples were finely ground before
digesting them with concentrated HNO3 (70%) in a water bath at
95 ◦C for 6 h. Solutions were filtered on 0.22 m membrane before
analysis (modified from Keller et al. [55]). Silicon was extracted
according to Guntzer et al. [56].