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TABLE W5. Grain yields of ten of the most promising durum lines compared to the most important
commercial varieties of bread and durum wheats in replicated yields tests, under 1969·1970 Sonora Mex.
ico conditions.
'
Variety
No.
015
045
057
09
02515
023
068
01
030
029
Cross
(RaE·Te 4 ) Stw. 63 x AA "s"
[T. die Varum (TME·Te 2 /I.B x W)]
CRANE "5"
(BYE·TACE x Te 4 ) (By 2 r Te x Stw. 63) AA "s"
BYE·Te~
B. Bal. (By 2 E·Te) x Cr "s"
(BYrTe~) x AA "S"
ALBATROSS = JORI 69
(I·B x LK) 60.120/TME·Te 2 jI.B x W)
(T. duro tipo, sph.Mogel. Karak x AA "s") (By 2 E·TACE·Te 3 )
Siete Cerros (bread wheat)
Inia 66 (bread wheat)
Ciano 67 (bread wheat)
Oviaehie 65 (dwarf durum)
Tehuaean 60 (durum variety)
Pedigree
27617·18M·6Y·OM
26636·1M·6R
23055.56M·5Y·l M.OY
27591.3M.3Y.OM
21276·3Y·1Y·1Y
27676·1M·1Y·OM
27512·16M·5Y·OM
26813-43Y·1M·OM
27680·2M·1Y·OM
Yield
kg/ha
9.722
9.665
9.472
9.242
9.378
9.444
9.117
9.060
9.044
9.029
9.036
8.065
7.044
7.563
4.822
Grain test
Weight
kg/hi
82.4
83.2
81.2
81.4
82.3
83.2
82.7
81.2
83.6
82.4
80.1
83.2
81.6
80.1
81.2
variety. Factors such as tillering, straw height
and strength, the number of spikelets per
spike, number of seeds per spikelet, the size,
weight and density of the grain and the growth
habit and light sensitivity, all strongly influence
yield. The dwarfing genes from Norin 10 were
transferred to the durum wheats more than 14
years ago in Mexico. Two dwarf varieti~s
Oviachic 65 and Jori 69 have been developed.
Oviachic 65 has not been highly successful,
despite the excellent agronomic plant type.
Both of the dwarf durum varieties have had
poor yield stability. Under certain favorable
conditions they have yielded more than the
best dwarf bread wheat varieties. Nevertheless
under other conditions which seem nearly
identical, yields have frequently been disappointing.
An analysis of the cause of unstable
yield in the dwarf durum varieties and lines
has estabjished that it is primarily related to
sterility of many florets when they are grown
under certain ill-defined conditions. It appears
that the instability of fertility is in some way
related to sensitivity to day length and perhaps
also to temperatures. These defects
have been probably indavertently exaggerated
in the past in the CIMMYT dwarf durum breeding
program because of the narrowness of the
genetic base. The relatively small durum breeding
program until recently was largely a backcross
program, which consequently reduced
even more the possibilities of overcoming the
aforementioned defects.
Three years ago an intensive crossing program,
employing many durums from the USDA
World Durum Collection, was initiated to correct
these and other defects. During the season
of 1969-70 at CIANO, out of 140 new lines
evaluated in yield tests, 109 outyielded Inia 66,
and 36 outyielded Siete Cerras. Eighteen of
the best lines yielded more than 9 metric tons
per hectare. The performance of 10 of the
best lines is shown in Table W5, together with
the bread and durum check varieties. In addition
to the very promising advanced generation
lines included in y'ield tests a number of
outstanding new crosses were identified in less
advanced generations.
The CIMMYT dwarf durum varieties have
been selected strongly for resistance to stem,
stripe and leaf rust in Mexico and excellent
resistance has been obtained. During the past
two years when they have been evaluated in
Tunisia many were found to be susceptible
to either stem or leaf rust, indicating different
races in the two regions. Fortunately some
high yielding Jines were found which are resistant
in both areas. Nevertheless, it has
become apparent that it is necessary to increase
the spectrum of rust resistance in the
CIMMYT materials as rapidly as possible.
Moreover, wheats that are to be grown in the
Mediterranean region need a high degree of
resistance to both Septaria and mildew. Many
of the lines from North Dakota carry good
resistance to mildew, perhaps derived from
Khapli. There is, however, a need to evaluate
all genetic stocks from the World Collection
for Septoria resistance in an area where severe
Septaria epidemics develop.
The phenotype of the best of the CIMMYT
dwarf lines, if they can be corrected for partial
sterility and strengthened in disease resistance,
give promise of outyielding the highest dwarf
bread wheats. This is the aim of the expanded
CIMMYT durum breeding program.
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