@article{epprod3878,
          volume = {58},
          number = {3},
           month = {["lib/utils:month\verb1_13878" not defined]},
          author = {O Babourina and K Voltchanskii and B McGann and IA Newman and Z Rengel},
            note = {The definitive publisher-authenticated version  http://www.oxfordjournals.org/

Copyright \copyright 2007 Oxford University Press
},
           title = {Nitrate supply affects ammonium transport in canola roots},
       publisher = {Oxford University Press},
            year = {2007},
         journal = {Journal of Experimental Botany},
           pages = {651--658},
             url = {http://eprints.utas.edu.au/3878/},
        abstract = {Plants may suffer from ammonium (NH4
+) toxicity when
NH4
+ is the sole nitrogen source. Nitrate (NO3
?) is known
to alleviate NH4
+ toxicity, but the mechanisms are
unknown. This study has evaluated possible mechanisms
of NO3
? alleviation of NH4
+ toxicity in canola
(Brassica napus L.). Dynamics of net fluxes of NH4
+, H+,
K+ and Ca2+ were assessed, using a non-invasive microelectrode
(MIFE) technique, in plants having different
NO3
? supplies, after single or several subsequent
increases in external NH4Cl concentration. After an
increase in external NH4Cl without NO3
?, NH4
+ net fluxes
demonstrated three distinct stages: release (t1), return
to uptake (t2), and a decrease in uptake rate (t3). The
presence of NO3
? in the bathing medium prevented
the t1 release and also resulted in slower activation of
the t3 stage. Net fluxes of Ca2+ were in the opposite
direction to NH4
+ net fluxes, regardless of NO3
? supply.
In contrast, H+ and K+ net fluxes and change in external
pH were not correlated with NH4
+ net fluxes. It is
concluded that (i) NO3
? primarily affects the NH4
+ lowaffinity
influx system; and (ii) NH4
+ transport is inversely
linked to Ca2+ net flux.}
}