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Published on: March 12, 2012
Tomato responses to ammonium and nitrate nutrition under controlled root-zone pH
M M Peet1, C D Raper, L C Tolley
1Dept. of Horticultural Science, North Carolina State University, Raleigh 27695-7609, USA.
Abstract:
Tomato (Lycopersicon esculentum L. Mill. 'Vendor') plants were grown for 21 days in flowing solution culture with N supplied as either 1.0 mM NO3- or 1.0 mM NH4+. Acidity in the solutions was automatically maintained at pH 6.0. Accumulation and distribution of dry matter and total N and net photosynthetic rate were not affected by source of N. Thus, when rhizosphere acidity was controlled at pH 6.0 during uptake, either NO3- or NH4+ can be used efficiently by tomato. Uptake of K+ and Ca2+ were not altered by N source, but uptake of Mg2+ was reduced in NH4(+)-fed plants. This indicates that uptake of Mg2+ was regulated at least partially by ionic balance within the plant.
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