Alleviation of nickel toxicity by ammonium supply to sunflower plants |
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Authors: | Zornoza P Robles S Martin N |
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Institution: | (1) Departamento de Química Agrícola. Facultad de Ciencias, Universidad Autónoma, 28049 Madrid, Spain |
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Abstract: | Phytotoxicity of nickel (Ni) varies within plant species and cultivars as well as with the concentration of Ni in the rooting
medium. Moreover, it is known that several nutrients can modify the plant response to excess Ni. Nitrogen can be absorbed
by plants as different N forms and because N metabolism and Ni are closely related, a hydroponic experiment was conducted
to study the effect of Ni toxicity on the growth, nutrient status of the different plant parts and leaf chlorophyll concentrations
in sunflower plants (Helianthus annuus L.) cv Quipu grown with different forms of N supply. The plants were grown under controlled
conditions for 35 days. Depending on the N source supplied, there were significant differences in the sensitivity of sunflower
plants to excess Ni. Tolerance was lowest when grown with NO3
− alone. A high Ni and NO3
− as the only N source resulted in reduced dry weight and significant decreases in nutrient concentration. Plants supplied
with a mixture of NO3
− and NH4
+ absorbed in the presence of Ni in solution about three times less Ni than those supplied with NO3
− alone. Consequently, there were great differences in Ni concentrations between treatments. With a N nutrition of 100% NO3
−-N, Ni supply led to severe growth inhibition. Just contrary, simultaneous supply of NO3
− and NH4
+ not only reduced Ni toxicity, but growth was even stimulated by Ni if supplied to plants fed with NO3
− and NH4
+. This indicates the significant role of the N form supplied in the behaviour of Ni toxicity in sunflower plants.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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Keywords: | ammonium Compositae nickel toxicity nitrogen source sunflower |
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