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FIGURE W1. Typical frequency distribution of
the nitrogen reducing ability of dfferent F:? wheat
o;eedlings.
..
II
U
~
24
~
u
12
II
.:
.Ċ
6
II
Ii
'0
..
.!
E:l
z
12
TABLE W 12. Nitrate reduction ability of several
of the bread wheat progenitors.
Progenitor Low Medium High Very High
Nadadores 63
SOnora 64-Yaqui 50. x
Gabolo
Sonora 64.Yaqui 50. x
Gaboto/lnia
'nia
Tobari 66
Sonora 64
Penjamo
Buck Atlanlico
Chris
Siele Cerros
Bonanza
Nor 67
Gabolo
Sonalika
Klein Rendidor
Yaqui 50
Palo (Rojo)
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
6
2 3 4 5 6
Activity class (activity measured as " moles NO"
reduced/hour/ grain of fresh weight)
more than 300 Fa lines selected from approximately
10,000 plants representing 65 tested
F;! populations have been planted and will
again be analyzed on an individual plant basis.
Plants will be selected from these populations
that have the necessary agronomic characteristics
such as good plant type and resistance
to diseases but also will possess the genetic
potential for high levels of nitrate reduction.
These plants will be incorporated into the
wheat breeding programs to be used as progenitors
for future wheat varieties.
Another approach is presently being tested
to obtain wheat genotypes with high nitrate
reducing potential. The bread wheat crossing
block (436 genotypes) has been analyzed in
the seedling stage under field conditions and
classified into activity categories (Table W12).
This data coupled with the F 2 distributions
provides some information on which progenitors
transmit high activity plants into the
segregating F 2 populations. It has been found.
for example, that "highs" such &s Tobari 66,
Buck Atlantico, Sonora 64, or Inia when used
in crosses consistently transmit "highs" into the
F;! population. Other progenitors such as Chris
fail to produce "highs". This study is pre-
sently being expanded to study the segregating
populations of "high" x "high" crosses.
Also in progress is a study of ten different
wheat varieties of different yield potentials,
protein content, maturity dates, plant types and
leve,ls of nitrate reducing ability. These varieties
are being analyzed weekly throughout
their entire growing season for nitrate reduction
and several other measurements. This
study was designed to determine what plant
characteristics are valuable in grain protein
production.
Agronomic and Soils Research on Wheat
Production
The soils and agronomic research being
done on wheat by CIMMYT in Mexico is presented
elsewhere in this report. Shortage of
staff has restricted studies in this field in recent
years. Currently a new staf,f member, Dr.
Anthony Fischer, is being added to expand
and strengthen the research in these disciplines.
The advent of the triple dwarf era -which
is now beginning in Mexico with the release
of the new dwarfs Yecora 70 and Saric 70­
will require new research to find how to effectively
utilize the yield potential of these varieties.
Limited preliminary work in this field
72