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As it is generally found when the initial level
of available nitrogen is low, the addition of a
small amount of nitrogen reduced both the
protein content .of the flour and the loaf volume.
These two parameters, after reaching a
minimum with the application of about 50 kg
of nitrogen per hectare, increased with higher
rates of fertilization in a nearly linear fashion
up to the 300 kg/ha rate. Above this level of
ferti Iization the protein percentage conti nued
to increase while the loaf volume remained
unchanged.
Sedimentation volume of the flour from the
two varieties was affected similarly by nitrogen
fertilization. The first increment of nitrogen
fertilization reduced the sedimentation volume
from 43 to 33 cc; hligher rates gradually increased
the sedimentation volume to a maximum
of 63 cc with the application of 400 kg
of nitrogen per hectare. The effect of nitrogen
fertilization on the general strength index of
the flour was very similar to the effect on
protein percentage.
Plant samples were taken from each experimental
plot at 36, 67, 95 and 126 days after
planting. The second sampling was made at
heading and the last at physiological maturity.
Except at the first sampling, the plants were
divided into leaf, stem and spike tissue. The
samples were washed, dried, ground and analyzed
for total nitrogen, phosphorus, and
potassium.
The effect of nitrogen fertil ization on the
nitrogen percentage in the wheat stems at
67, 95 and 126 days after planting is shown in
Fig. 2. At the two earlier sampling dates, the
application of 100 kg of nitrogen per hectare
clearly reduced the nitrogen percentage in
the stems. Higher rates of nitrogen fertilization
produced a logarithmic type increase in
the nitrogen percentage. At 67 days after
planting, the nitrogen percentage in the stem
was increased from 1.13 to 2.25 by the application
of 400 kg of nitrogen per hectare.
The effect of nitrogen fertilization on the
nitrogen percentage in the wheat leaves and
spikes was similar to the effect on the stems.
A reduction in the nitrogen percentage with
the application of 100 kg of nitrogen per hectare
was noted in the leaf at 95 and 126 days,
and in the grain at 126 days. Logarithmic or
linear increases in the nitrogen percentage of
both leaves and spikes were observed at
higher rates of nitrogen fertilization at all sam-
Plant analyses of the wheat samples are carried out in the soil fertility laboratory of the Graduate College
at Chapingo. Total nitrogen is determined by the micro-Kjeldahl method, which is shown here at
distillation stage.