Abstract:
A greenhouse study was carried out to determine the
effect of nitrogen forms and
different O
2
levels on growth and mineral nutrient concentratio
ns of eggplant. The
experimental design was a completely randomized fac
torial experiment with two factors,
namely: (i)
Two
nitrogen forms (Ca(NO
3
)
2
and (NH
4
)
2
SO
4
) and (ii) Three O
2
levels of the
nutrient solutions (1
±
±±
±
0.3, 2
±
±±
±
0.3, 3
±
±±
±
0.3, and 4
±
±±
±
0.3 mg L
-1
O
2
). The results showed that
ammonium application reduced all measured parameter
s of vegetative growth, whereas
high oxygen levels increased the vegetative growth.
Comparing with nitrate-N,
ammonium application increased the concentrations o
f NPK and Zn in leaves and Zn and
Cu in roots, while it decreased the concentration o
f Mg, Ca, Cu, Mn, and Na in leaves and
Ca, Mg, Mn, and Na in roots. High levels of O
2
increased N, Mg, Ca, Cu, and Mn content
of leaves, as well as Mn and Na content in roots, w
hile it decreased the concentration of K
in leaves and P and Zn in roots. According to the r
esults, the increase in O
2
amount of the
nutrient solutions partly alleviated ammonium toxic
ity in eggplant. Therefore, in floating
hydroponic cultures, O
2
level and its distribution should be controlled an
d must not be
lower than 4 mg L
-1
.
Keywords:
Ammonium, Nitrate-N, Nutrient solution aeration, S
oilless culture,
Solanium
melongena
.
