INFLUENCE
OF NICKEL
FERTILIZATION ON
THE YIELD, QUALITY
AND THE
ESSENTIAL OIL
COMPOSITION
OF
CORIANDER LEAVES
[55]
Laila,
M. Helmy1; M.E. Khattab2 and Nadia Gad3
ABSTRACT
Coriander plants (Coriandrum sativum L.) seeds were grown in
plastic pots filled with Nile-delta clay soil during 1999/2000 and 2000/2001
seasons. One-month-old plants were soil supplemented with 0, 20, 40 and 80 mg Ni
per kg soil using NiSO4 solution of different concentrations.
Coriander leaves were first harvested 2 months after
seed sowing and
reharvested again for 3 additional harvests
at monthly
intervals. At each harvest, plant height, leaves fresh and dry weights,
number of leaves per plant, leaf area and chlorophyll contents were measured.
Dried leaves were then analyzed for N, P, K, Ca, Mg, Fe, Mn,
Zn, Cu
and Ni contents.
Total soluble solids (TSS), titratable acidity (TA), L-ascorbic acid (LAA)
contents in the fresh leaves of the four harvests, nitrate and ammonium contents
in the fresh leaves of the first two harvests were measured, while those of the
second two harvests were used for essential
oil extraction.
Identification of essential oil constituents were conducted for the fourth
harvest in the second season. Low levels of Ni fertilization, particularly 40
mg/kg soil, increased
coriander leaf yield
and quality without
affecting leaf chlorophyll and Fe contents, but reduced TSS, LAA, nitrate
and ammonium levels.
Increasing Ni levels up to 80 mg/kg soil resulted in visible
symptoms of leaf chlorosis which coincided with a sudden drop in leaf
chlorophyll content and reduced N and Mg levels relative to that of the
control. Thirteen
compounds of coriander leaves essential oil were identified. 2-decenal
was the first major oil constituent forming
about (26%)
of the
oil. The
low levels of Ni fertilization, particularly 40 mg/kg clay soil, improved
not only coriander leaf yield and quality (i.e. leaf area, mineral content, oil
yield and flavor) but also the leaves were safer for human consumption since
their nitrate and ammonium contents were significantly reduced.