Root morphology of maize under homogeneous or spatially separated supply of ammonium and nitrate at three concentration ratios |
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| Authors: | Marcus Schortemeyer Boy Feil |
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| Institution: | 1. Institute of Plant Sciences , Swiss Federal Institute of Technology , Universit?tstr. 2, CH‐8092, Zürich, Switzerland;2. Research School of Biological Sciences , The Australian National University , Canberra, ACT, 2601, Australia E-mail: marcus@rsbs‐central.anu.edu.au.;3. Institute of Plant Sciences , Swiss Federal Institute of Technology , Universit?tstr. 2, CH‐8092, Zürich, Switzerland |
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| Abstract: | Maize (Zea mays L. cv. Anjou 256) seedlings were grown hydroponically for 10 d in a split‐root system (3mM N; pH 5.5) under either a homogeneous supply (HS) or a simultaneous, but spatially separated supply (SS) of NH4 + andNO3 ‐. Treatments comprised three NH4 +:NO3 ‐ ratios (1:4, 1:1, 4:1). Shoot dry matter and various root traits (dry matter, number of laterals, length of main axes, total root length and total root surface area) were determined. For all NH4 +:NO3 ‐ ratios, shoot dry matter, root dry matter, total root length, and root surface area, were greater under HS than under SS. Under both SS and HS, increasing NH4 +:NO3 ‐ ratios resulted in decreased shoot and root dry matter production, but did not alter the shoot:root dry matter ratio. Under SS, root dry matter, root length, and root surface area was greater on the NO3 ‐‐fertilized side than on the NH4 + ‐fertilized side. The allocation of root dry matter, root length, and root surface area to the NH4 + or NO3 ‐ compartments was unaffected by changes in the NH4 +:NO3 ‐ ratio. Enhanced NH4 + nutrition has detrimental effects on top growth, but roots are apparently unable to avoid excessive NH4 + uptake by proliferating in zones where NO3 ‐ is the only form of N. |
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