2.3.2. Mineral composition
Oven dry plant shoot and fruit samples, from both crops, were
used for mineral analysis according to (AOAC, 1990). In brief, the
samples were dried to 60
◦
C using ventilated oven (1445 SHEL LAB)
then the samples were ground using stainless steel blender. Samples from the ground materials were ashed at 450–500
◦
C for 4 hrs
using Thermo Scientific Muffle Furnaces (Thermolyne
®
). A 10 ml of
0.1N HNO3were added to 100 mg of the plant ash then the mixture
was heated for 10 min. The resulting solution was then filtered into
50 ml volumetric flask. An additional 10 ml of the HNO3solution
was added to the residue of plant ash for further dissolution of that
material and finally the volume of the filtrate was made to 50 ml using deionized water. Concentration of soluble K was determined
by flame photometery (PFP-7 flame photometer). Soluble Ca and
Mg were determined by atomic absorption spectrophotometery.
Total P was determined in accordance with Olsen method (Jones,
2001). Total N was determined by Kjeldal method (Waling et al.,
1989)