
TY  - JOUR
A1  - Chanda, SV 
A1  - Joshi, AK 
A1  - Krishnan, PN 
A1  - Singh, YD 
T1  - <i>In vivo</I> Nitrate Reductase Activity in Leaves of Pearl Millet, <I>Pennisetum americanum</I> (L.) Leeke
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 1987
VL  - 14
IS  - 2
SP  - 125
EP  - 134
KW  - 
UR  - https://doi.org/10.1071/PP9870125 
N2  - In the in vivo assay of nitrate reductase (NR) in P. americanum leaves, addition of 1% (v/v) Triton X-100, potassium phosphate buffer (80 mM, pH 7.4) and 1.13 mM NADH to the assay medium resulted in maximum activity. With increasing concentration of NADH, saturation-type kinetics were observed. Based on this data metabolic pool concentration for NADH and apparent Km for nitrate reductase were determined.    In field studies with cultivars BJ-104, J-104 and 5141-A of P. americanum, the relative limitation of NO3-, NADH and nitrate reductase in NO3- assimilation was determined. NR activity was measured by four modifications of the in vivo assay technique (with NO3-, with NADH, without NO3- and NADH and with both NO3- and NADH additions to the reaction mixture) and with one in vitro technique. For all the cultivars, NADH was the major rate-limiting factor for in vivo assay during early growth stages, while at later stages, NO3- was limiting. At no stage was NR rate-limiting. It is concluded that NR activity alone may not serve as biochemical marker for improved efficiency of utilisation of nitrogen in P. americanum. 
ER  -

