New Zealand Journal of Crop and Horticultural Science abstracts
Influence of different nitrogen sources and levels on ion content of
cabbage (Brassica oleracea var. capitate)
Metin Turan
Department of Soil Science
Faculty of Agriculture
Atatürk University
25240 Erzurum, Turkey
email: mturan@atauni.edu.tr
Figen Sevimli
Department of Public Health
Faculty of Medicine
Atatürk University
25240 Erzurum, Turkey
Abstract The objective of this study was to determine
the effects of different nitrogen (N) sources and levels on ion content in
cabbage (Brassica oleracea var. capitate ‘Yalova-1’). In the
process of ion uptake by plants, electro-neutrality is maintained both by
the plant and the nutrient medium in which the plant is grown. N fertiliser
not only affects yield but also the quality of the plant. Nitrates convert
to nitrite in plant tissues which may cause health problems in infants and
also form carcinogenic substances. Higher doses of nitrites change haemoglobin
to methaemoglobin and this inhibits the transport of blood oxygen in the
human body. Increased rates of N fertilisers also cause the accumulation
of oxalic acid in vegetables. Oxalic acid causes acute toxicity if taken
with calcium (Ca) and this forms stones in the kidney. Cabbage plants were
grown in field conditions with five N fertiliser types, four doses and three
replications. The treatments of N consisted of: no added fertiliser; 100,
200, and 400 kg N ha–1 as potassium nitrate, ammonium nitrate,
urea, ammonium sulphate, and farmyard manure. The results demonstrate that
plant head weight was generally greater when mineral fertiliser rather than
organic fertiliser was supplied to plants. In the 400 kg N ha–1
treatment as potassium nitrate, ammonium nitrate, ammonium sulphate, urea,
and farmland manure application, plant yields were 66%, 61%, 40%, 49%, and
44% higher than with no added fertiliser, respectively. When the data were
subjected to multiple regression analysis, effects of ammonium nitrate fertiliser
application at 342 kg N ha–1 on plant yields (3333 g plant–1)
were higher than that of other fertiliser applications. With increasing NO3–
nutrition, the bulk of anion charge appeared as organic anion accumulation
in the plants. The increase in organic anion accumulation was paralleled
by an increase in cation concentration (K+, Ca+2, Mg+2,
Na+). Total inorganic anion levels (NO3–,
SO42–, H2PO4–, Cl–)
were relatively constant. The effects of increasing NO3–
nutrition in stimulating organic anion accumulation such as glutamate, malate,
and oxalate were far greater than ammonium and the other nutrient forms.
Nitrate content of plants increased with the increasing N application, especially
with nitrate fertiliser. The increases observed in the plant were highest
in the plots with potassium nitrate applied and lowest in plots with no added
fertiliser treatment. The results also indicated that farmyard manure was
much more suitable than mineral fertilisers for plant quality according to
lower total N, nitrate, and oxalic acid contents of cabbage plants. However,
ammonium sulphate application at the rate of 250 kg N ha–1 was
the most suitable fertiliser application rate for plant quality according
to lower risk yields of plants (2650 g plant–1) for human nutrition.
Keywords nitrogen fertilisation; organic acid; nitrate
content; cabbage; yield
H04030; Online publication date 15 July 2005 Received 16 March 2004, accepted
1 March 2005
New Zealand Journal of Crop and Horticultural Science, 2005, Vol. 33:
241-249
0014-0671/05/3303-0241 © The Royal Society of New Zealand 2005
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