New Zealand Journal of Agricultural Research abstracts
Effects of foliar and root applied nitrogen on nitrogen uptake and
movement in white clover at low temperature
M. L. Castle1,2
J. R. Crush1
J. S. Rowarth2,*
1AgResearch, Ruakura Research Centre
Private Bag 3123
Hamilton 3240, New Zealand
2UNITEC, Private Bag 92025
Auckland 1142, New Zealand
*Corresponding author: J. S. Rowarth, Massey University,
Private Bag 11222, Palmerston North 4442, New Zealand.
Abstract ‘Grasslands Huia’ white clover
plants were grown at
a constant root and shoot temperature of 8°C in a controlled
environment room. Nitrate or urea labelled with 15N was
applied to the foliage, foliage plus the roots, or to the roots only.
After 21 days, plants supplied with foliar nitrogen (N) or with N to
the foliage plus roots, produced significantly (P < 0.05)
more lamina dry weight than plants supplied with N to the roots only.
Plants supplied with N to the foliage contained significantly (P
< 0.05) more lamina 15N than plants supplied with N
to the foliage plus the roots or to the roots only. From 14 days
onwards, plants supplied with foliar N, or N to the foliage plus the
roots, had significantly (P < 0.05) higher leaf areas than
plants supplied with N to the roots only, irrespective of the form of N
applied. By 21 days, plants supplied with foliar nitrate or urea had
significantly (P < 0.05) higher photosynthesis,
transpiration, stomatal conductance rates, and lamina sucrose
concentrations, than plants supplied with N to the roots. The
experiment demonstrated the importance of N availability as a
rate-limiting factor on starch and sucrose synthesis and, in turn, on
foliage growth at low temperatures in white clover.
Keywords nitrate; roots; starch; sucrose;
transpiration;
Trifolium repens L.; urea; white clover
A07014; Online publication date 29 October 2007; Received 20
February 2007; accepted 5 September 2007
New Zealand Journal of Agricultural Research, 2007, Vol. 50:
463–472
0028–8233/07/5004–0463 © The Royal Society of New Zealand 2007
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