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Micronutrients and nitrogen metabolism: II. Effect of micronutrients on the assimilation of ammonium and nitrate ions by maize (Zea mays L.)
K.S. DHILLON, B.A. YAGODEEN and V.A. VERNICHENKO
Plant and Soil
Vol. 103, No. 1 (1987), pp. 51-55
Published by: Springer
Stable URL: http://www.jstor.org/stable/42936798
Page Count: 5
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A sand-culture experiment was conducted to study the influence of a deficiency of and an excess of micronutrients on the uptake and assimilation of $NH_4^ + $ and $NO_3^ - $ ions by maize. By studying the fate of ¹⁵N supplied as ¹⁵NH₄NO₃ or NH₄¹⁵NO₃, it was demonstrated that in maize plants NH₄-N was absorbed in preference to $NO_3^ - $-N. The uptake and distribution of N originating from both $NH_4^ + $ and $NO_3^ - $ was considerably modified by deficiency of, or an excess of, micronutrients in the growth medium. The translocation of $NO_3^ - $-N from roots to shoots was relatively less than that of $NO_3^ - $-N. Deficiency as well as excessive amounts of micronutrients, in the growth medium, substantially reduced the translocation of absorbed N into protein. This effect was more pronounced in the case of N supplied as $NO_3^ - $. Amino-N was the predominant non-protein fraction in which N from both $NH_4^ + $ and NO₃ tended to accumulate. The next important non-protein fractions were $NO_3^ - $-N when N was supplied as $NO_3^ - $ and amide-N when $NH_4^ + $ was the source. The relative accumulation of ¹⁵N into different protein fractions was also a function of imposed micronutrient levels.
Plant and Soil © 1987 Springer