Summary. Experiments were conducted at 3 sites in
Western Australia in 1993 using 33 wheat cultivars and crossbreds. Two rates
of applied nitrogen fertiliser (0 and 40 kg/ha of nitrogen) were used to
screen the lines for efficiency of nitrogen uptake, grain yield and grain
protein production per unit of nitrogen applied, and nitrogen translocation to
the grain. This information can be useful in determining nitrogen fertiliser
strategies for wheat cultivars in the field. Nitrogen uptake in the plant tops
was measured during the season and in the grain and straw at maturity.
Grain yield, grain protein and nitrogen efficiency parameters were not
markedly different between grain quality grades which are largely based on
grain hardness. Yield efficient lines (high net yield increase per unit of
applied nitrogen) were characterised by greater net uptake and net utilisation
efficiencies but had similar yields and grain protein percentages as yield
inefficient lines. Protein efficient lines (high net grain protein increase
per unit of applied nitrogen) also had greater uptake efficiencies but lower
utilisation efficiencies than protein inefficient lines.
No lines were both yield and protein efficient suggesting that lines either
use fertiliser nitrogen preferentially in yield production or in production of
protein. The results indicate that in nitrogen-responsive situations it will
be more profitable to use yield-efficient lines. Further investigation is
needed to examine the suggestion that where soil nitrogen levels are higher
(and yield responses to nitrogen are less) a greater economic return may come
from using protein efficient lines.
Some wheat lines had a high ability to recover fertiliser nitrogen applied to
the crop. Others had a high ability to take up soil nitrogen. It is postulated
that these differences may be due to differences in root systems. Some mid-
and long-season lines that had high concentrations of nitrogen in the tops at
anthesis metabolised that nitrogen poorly into grain yield or protein. This
suggests that nitrogen efficiency may be partly related to maturity relative
to length of growing season.
Optimizing Parameters of CSM-CERES-Maize Model to Improve Simulation Performance of Maize Growth and Nitrogen Uptake in Northeast China
