A Database for Triticeae and Avena
SMALL GRAIN INSTITUTE
Private Bag X29, Bethlehem, 9700, South Africa.
Because of low wheat price, high input costs, unfavorable weather
conditions, and standards set by the "new free market environment"
that has ruled South Africa since the end of 1997, wheat production
has decreased drastically. Thus, wheat research is becoming increasingly
important to aid the farmers in producing a cost-effective crop.
H.A. van Niekerk, J.C. Aucamp, O. Müller, and D.J. Exley.
Traditionally, between 50 % and 60 % of the total wheat production
in South Africa can be accounted for by dryland wheat production
in the summer rainfall region and results from the planting of
mainly winter and intermediate bread wheat types in the Eastern,
Central, and Western Free State. However, we are concerned that
farmers planted 56 % less wheat (during 1998) than the 790,000
ha that was planted in the previous year.
The goal of research is to develop improved, high-yielding,
well-adapted and stable cultivars of winter and intermediate wheat
for dryland conditions in the Free State. Furthermore, these cultivars
have to completely meet all the quality requirements set by the
processing industry. To help reduce the farmer's risk, cultivars
must have a high falling number; very good preharvest sprouting
resistance; and resistance to disease (especially yellow, stem,
and leaf rusts) and RWA to help the farmer reach maximum yield
and keep input costs as low as possible.
The highlight of this past season was the release of Elands, an
intermediate-type wheat cultivar, which almost complies with the
above-mentioned idiotype. Elands is a high-yielding, well-balanced,
bread wheat with high flour extraction, high water absorption,
good mixing characteristics, and excellent protein quality. The
cultivar completely meets with all the quality requirements of
the new market environment in South Africa. Elands is resistant
to stem rust, but unfortunately is susceptible to leaf and yellow
rusts. Elands has very good RWA resistance, excellent preharvest-sprouting
resistance, and exceptional hectoliter mass. This cultivar will
be planted commercially for the first time during the 2000 wheat
H.A. van Niekerk, A.D. Barnard, M.S.S. Jordaan, and T.G. Paxton.
Dryland conditions. The objective of spring wheat breeding
is to develop and release improved high-yielding, well-adapted,
stable cultivars superior for one or more important characteristics.
The Western Cape is traditionally a low protein environment. Grain
quality consists of a number of characteristics that are influenced
by different factors, some genetic, some environmental, and some
both. To successfully increase the most important quality characteristics
and yield simultaneously, the choice of breeding parents is extremely
important. Therefore, a study was undertaken to identify suitable
parental lines that are stable over environments, which can be
used to produce superior progeny for yield and quality characteristics
in the Western Cape.
Six parental lines were planted at the Langgewens (Swartland)
and Tygerhoek (Rûens) experimental farms. The climatic conditions
and soil types of these two localities differ completely. A randomized
complete block design with four replications was used. An ANOVA
was performed, and showed locality, cultivar, and the 'locality
x cultivar' interaction.
Some cultivars were more stable over environments; therefore,
parents should be selected on good average performance across
localities. From this study, three stable cultivars (Kariega,
SST 57, and Palmiet) were identified as useful for the improvement
of quality characteristics. Because of their stability across
environments, the genotype plays a more important role in the
expression of these traits. No stable-yielding cultivar was identified.
Gamtoos proved to be the best parental line to improve both farinograph
absorption and stability, but because of the negative association
of the T1B·1R translocation with quality, this cultivar
should be used to a limited extent.
Irrigation conditions. This breeding program is responsible
for developing short-stature, spring wheat cultivars for the warmer
and cooler irrigation areas.
The requirements for a new cultivar evidently intended for
irrigation include the following:
Since 1990, the cultivars Marico (1992) and Kariega (1993)
were released from this program. Currently, breeding varieties
able to hold up to the outstanding bread-making quality characteristics
of Kariega is extremely difficult.
New and future releases from the breeding program. The
Wheat Technical Committee accepted KBSP95/26 for final classification,
and this line will be marketed as Steenbras. BSP 97/1 was classified
provisionally and will be sent for final classification at the
end of this season. The average yield data for Steenbras (Fig. 1) show that the
yield averages for later planting dates in the irrigation areas
compare well to that of Palmiet. This cultivar also is a higher-yielding
double dwarf than SST 822.
The yield performance of BSP 97/1 compares well to that of
Kariega, whereas its hectoliter mass is higher and more stable
over environments. The agronomic data for Steenbras and BSP97/1
are shown in Table 2.
New and interesting germ plasm developments. Thirteen
lines selected from the drought-tolerance trial during 1997, together
with five local standards, were evaluated in two trials at the
Upington research station. The control trial received optimal
irrigation, whereas the other trial was evaluated under water-deficient
conditions. Both these trials were screened for heat tolerance
with an infrared gun. CIMMYT researchers use canopy temperature
depression (CTD) as a rapid, early generation screening tool for
heat tolerance in wheat. The data still need to be analyzed statistically.
If this technique can be implemented successfully at SGI, it would
be possible to develop lines capable of keeping up their performance
under water-deficient conditions. These lines can further reduce
the risk and input costs for the irrigation farmer in a country
with poor water resources.
A take-all trial at Potchefstroom was conducted for the second
time to determine the resistance levels of all the most popular
spring wheat cultivars currently in production in the summer and
winter rainfall areas. A total of 13 cultivars, including Potch
92 and Potch 93, which showed high levels of resistance during
the previous season, were evaluated. The aboveground infection
was expressed as a percentage of the infected plants in each row
compared to the total amount of plants in each row. Potch 92 and
93 again showed lower susceptible percentages than all the commercial
cultivars, except SST 57. Potch 92 showed the best resistance,
and T4 showed acceptable resistance levels. The F2 population,
from crosses between Potch 92 and 93 with Kariega and other parents,
was planted at the same locality. Five spikes were selected from
rows that showed less than 15 % white spikes. These spikes were
bulked and will be evaluated in the F3 generation at the same
locality this season.
Nitroweat is a bacterial inoculant used on small grain crops
like wheat in order to enhance root growth and nutrient uptake.
Six trials were planted in the irrigation areas. Each trial consisted
of large strips split into a control and a Nitroweat treatment.
Small plots, each 1 m2, were cut from each trial. Hectoliter mass,
yield, and protein content were determined for these samples.
A minimum of 12 samples/treatment was taken at each locality.
This data show significant positive increases in profits except
for Delmas, where the trial was harvested too early, which negatively
influenced hectoliter mass. The differences between the control
and treatment for each locality are in Table 3.
A.D. Barnard and A. Otto.
To prevent genetic narrowing, new germ plasm is evaluated annually
for agronomic traits, disease resistance, and quality in the International
Nurseries project. This evaluation is very critical and includes
a wide array of germ plasm, which is collected on a worldwide
scale. Most of these genotypes are recently developed and unique,
representing the cream-of-the-crop from the previous year. During
the past 3 years, these lines were especially useful for selecting
sources of stripe rust resistance to a disease that currently
occurs widely in South Africa. Various numbers of new sources
of genetic diversity are obtained on a regular basis from CIMMYT
(Mexico), the U.S.A., Turkey, Germany, Spain, and Romania. During
the past season, wheat and barley lines from the ICARDA program
in Syria also were added. Selections of lines from these nurseries
and programs are included in the various breeding programs at
the Small Grain Institute to further the development of suitably
adapted cultivars for the wheat industry in South Africa. Purposeful
crosses also are performed on outstanding germ plasm.
H.A. van Niekerk, F.P. Koekemoer, C.W. Miles, K.B. Majola,
and M.L.T. Moloi.
The wheat quality laboratory has completed the analyses of
the South African wheat cultivars to determine the relative milling
and baking worth, including bran carrying capacity, on a scientific
and selection-index basis. The information obtained from these
analyses will create clear market signals as to what the market
requires and lead to concomitant higher prices for improved quality.
Therefore, this laboratory has become an integral part of the
breeding programs at the Small Grain Institute. Other departments
at the Small Grain Institute, wheat producers in the area, small
millers, and universities make use of this laboratory and contribute
to the more than 50,000 analyses performed by this laboratory
A.F. Malan and M. Ncala.
During the past 5 years, a protocol was developed to suit the
needs of the Small Grain Institute for doubled haploids of wheat.
Maize-wheat crossings were used to achieve the goal. Several maize
pollinators and hormone treatments were tested, but the best results
were achieved with the U.S. cultivar Miricle, followed by two
consecutive treatments with the hormones 2,4-D and gibberellic
This technique was standardized and currently is applied as
a routine protocol in the tissue culture laboratory at the Small
Grain Institute. The technique is used extensively on the early
generation, segregating material to produce large amounts of pure
breeding lines for selection purposes.
Furthermore, this laboratory is responsible for generating
double-haploid material for the SGI barley breeding program. Between
15,000 and 20,000 anthers are placed on medium per year.
R. Prins, V. Ramburan, and W.H.P. Boshoff; L.A. Boyd and T.
Worland (Cereals Research department John Innes Centre, UK); Z.A.
Pretorius (Plant Pathology Department, University of Free State,
RSA); and J.H. Louw (University of Stellenbosch, RSA).
Results from a 'Kariega/Avocet 'S'' F2 population suggested
that unidentified adult plant resistance to yellow rust in the
South African wheat cultivar Kariega is not monogenic and that
a quantitative genetics approach, employing QTL mapping procedures,
should be followed. A DH-mapping population consisting of 150
lines has been developed by the wheat-maize technique from a 'Kariega/Avocet
'S'' cross, and AFLP and SSR markers were identified in the two
parents. The primary aims are to increase the number of markers
in order to cover the entire genome as far as possible and also
to search for RFLP markers in regions where useful SSR markers
cannot be identified. Initial greenhouse tests for adult plant
resistance in genetic material derived from Cappelle Desprez shows
that Yr16 (APR) is effective against the South African
pathotypes (6E16 and 6E22). This material will undergo further
testing in field trials this year. Should the result be confirmed,
the Yr16 (APR) gene will be used in the breeding programs.
HJJ van Zyl.
Soil acidity is the most severe chemical limitation of crop
production in the Eastern Free State. Continuous soil cultivation
accelerated the natural process of acidification to such an extent
that 75 % of the regions soils have pH-values of 4.5 (KCl) and
lower. The stressful environment in which the plant is grown and
an excess of aluminium in the soil can cause severe damage to
the roots, resulting in significant yield losses.
The response of three wheat cultivars differing in aluminium
tolerance was measured at different lime levels. Biomass and yield
indicated that Tugela-DN (good tolerance) could produce economical
yields on acid soils. The yield of Tugela-DN increased significantly
when lime was applied. Gariep (medium tolerance) and Limpopo (susceptible)
were not able to produce economical yields on acid soils. Liming
increased the yield of both these cultivars to economic levels.
H.J.J. van Zyl.
Various soil factors influence the availability of micronutrients
for plant uptake. Even though micronutrients are utilized in small
amounts by the plant, they play an important roll in the physiology
of the plant. When deficiencies of one or more of these elements
occur, normal growth and production are not possible.
The influence of micronutrient foliar applications on wheat
yield and quality were investigated. Different micronutrient products
were applied at different growth stages. No significant differences
were found between the different products. An early application
± 40 days after planting produced higher yields than applications
at flag-leaf stage (± 90-100 days after planting). The
protein content and hectoliter mass were not significantly different
between the treatments.
W. Otto, W. Kilian, H.C.S.A. van der Merwe, E. van der Merwe,
B. van Rensburg, and C. Fourie.
Trials were planted in the Vaalharts-, Riet River-, and Loskop-irrigation
schemes to evaluate the influence of split applications of nitrogen
on the growth, yield, and grain quality of wheat cultivars. Kariega
and SST 825 were planted at Vaalharts and Riet River, whereas
Kariega and SST 822 were planted at Loskop. Nitrogen was applied
at planting, at early and late tillering, and at the flag leaf/ear
emergence growth stages. A total of 200 kg N/ha was applied at
Vaalharts and Riet River and 175 kg N/ha at Loskop.
Yield levels in the trials in 1998 were on average 4 t/ha at
Loskop and up to 8 t/ha at Vaalharts and Riet River. The split
application of N resulted in significant yield responses. The
split applications of 100-125 kg N/ha at Loskop and 125-150 kg/N
ha at Vaalharts and Riet River applied at planting, followed by
25 kg N/ha applied at late tillering, and 25-50 kg N/ha at flag
leaf stage produced yields of 8.2 to 8.4 t/ha (Riet River), 5.9
to 6.3 t/ha (Loskop), and 9.3 to 9.9 t/ha (Vaalharts). This treatment
also produced the highest hectoliter mass of the grain, which
indicates the positive effect of N applications on kernel size
and weight during the later growth stages. Protein content of
the grain was increased by application of N at the flag-leaf stage,
with average increases of 0.51 % (Riet River), 0.29 % (Loskop),
and 0.32 % (Vaalharts). These results indicate that the management
of N up to the late-tillering stages is aimed at optimizing yield
potential, and N applications during the later growth stages will
benefit grain protein content. The results from this project are
of great importance to the wheat producer in the current marketing
system. They allow recommendations to producers regarding the
amount of N and split applications of N to reach yield potential
levels and produce acceptable levels of grain quality. The future
aim of this project is to calculate and predict the contribution
of N by the soil, determine N uptake curves of cultivars, and
to use the resulting values to further adapt the N recommendations.
W. Otto and W. Kilian.
This project consists of a long-term trial site. In one trial,
the long-term effect of phosphorus applications (0-45 kg P/ha,
applied since 1983) on yield and soil analyses was determined.
On an adjacent site (NXP), the effect of phosphorus applications
(0-32 kg/ha) in combination with nitrogen applications (0-60 kg
N/ha) on yield and soil analyses data were evaluated.
The soil analyses showed that the soil P values changed relatively
slowly in response to P applications. The initial value of 12.5
mg/kg (Bray 1) changed to 11 mg/kg on the plots receiving no P
application and increased to 38 mg/kg at the 45 kg P/ha level
of application. Yields increased significantly in the long-term
P trial (1983-97) (average yields were 1.8 ton/ha) with application
of P up to 10 kg P/ha, but no differences occurred in measured
yields between the 10-45 kg P/ha levels.
A similar response pattern was found in the NXP trial, with
increases in yields up to the 8 kg P/ha level, but with no further
significant yield responses up to the 32 kg P/ha level. Yields
were increased with N applications up to the 30 kg N/ha level,
but no differences occurred between the 30 to 60 kg N/ha levels.
Protein levels of the grain were increased with nitrogen applications,
and the largest response occurred at the 45-60 kg N/ha levels.
These results confirm the current recommendations for nitrogen
and phosphorus applications under rain-fed conditions, at the
yield levels measured in these trials. Furthermore, these results
indicate the importance of balanced fertilizer application for
the production of high-quality grain.
W. Otto, W. Kilian, and T. Steyn.
The aim of this project is to determine the influence of soil
nitrogen applications on growth and yield of wheat. The project
is conducted on trial sites representing three of the major wheat
production areas in the summer rainfall region of the Free State
Province. These trial sites are at Petrusburg (Western Free State),
Kroonstad (Central Free State), and Bethlehem (Eastern Free State).
Wheat was cultivated in a fallow-wheat/wheat-fallow rotation system,
with nitrogen levels of 0 up to 60 kg N/ha applied. Aboveground
biomass development and the N-uptake pattern in combination with
soil N analyses were measured on selected treatments.
Initial soil mineral N content at planting (1997) indicated
relatively high values of residual N in the profile (0-1,200 cm)
following the fallow period (Petrusburg: 185, Kroonstad: 260,
and Bethlehem: 299 kg N/ha). Biomass development was increased
by N applications, but heat and moisture stress during the later
growth stages depressed the response and yield levels. Average
yields of 2.2 t/ha at Kroonstad, 0.9 t/ha at Petrusburg, and 2.4
t/ha at Bethlehem, were produced. Yields were increased significantly
with N applications, with responses up to the 10-20 kg N/ha levels
at Petrusburg, the 20-30 kg N/ha levels at Kroonstad, and the
30-45 kg N/ha levels at Bethlehem. Grain-protein content increased
in response to increased N application: from 13.4 to 11.5 % (0
to 60 kg N/ha) at Kroonstad, from 11.8 to 12.2 % (0 to 30 kg N/ha)
at Petrusburg, and from 10.1 to 12.3 % (0 to 60 kg N/ha) at Bethlehem.
Compared to 1997, the 1998 data showed lower yields and grain-protein
contents at Bethlehem and Kroonstad and a similar response at
Petrusburg. Lower soil mineral N values at the start of the growing
season (Petrusburg: 45-50, Kroonstad: 116-150, and Bethlehem:
147-199 kg N/ha) and lower rainfall during the 1998 growing season
partly of the explain the decrease. At Kroonstad, average yield
levels were 0.9 t/ha, with no response to N applications, but
grain-protein content increased from 10.9 to 11.5 % as N applications
increased to 60 kg N/ha. Average yields of 1.88 t/ha were recorded
at Bethlehem; positive responses occurred in yield to increased
N applications (45-60 kg N/ha) and in protein content (9.1 to
10.0 %) with applications up to 60 kg N/ha. At Petrusburg, yields
were increased at applications of 30-40 kg N/ha, which resulted
in lowered protein values (13.6 to 10.5 %) for these treatments.
These response patterns indicate that in a wheat-wheat rotation
system, N can become deficient, resulting in lowered yields and
reduced grain-protein content, although lower yields also can
occur as a result of moisture availability and rainfall distribution.
Nitrogen response is in accordance with the current N recommendations
for wheat production under rain-fed conditions at the yield levels
produced. The possible effect of soil mineral N values, in combination
with N applications on growth and yield, is influenced to a large
extent by climatic conditions (rainfall and temperature) during
the growing season. The interaction between these parameters must
be investigated to integrate soil N analyses values into fertilizer
No-till. No-till has not been kind to maize farmers who tried
the practice during the 1980s, because of the Diplodia crop-rot
epidemic. However, deregulation of the crop industry and the high
input cost/producer price squeeze have forced crop producers to
consider alternative farming practices. Conservation tillage,
including no-till, is once again considered a respectable crop-production
technique. Two reasons are the availability of no-till planters
today, which was not available a few years ago, and the increase
information about no-till farming system.
No-till requires the highest level of management skills of
all the forms of cultivation, conventional tillage included. One
reason is that a very high degree of understanding of the requirements
of the technique is necessary. A very definite change in mindset
from that for conventional tillage is required, and once the mindset
has been acquired, one really has arrived.
Minimum tillage. Tillage costs have risen drastically in the
last few years, especially during 1996 and 1997. The weakening
of the Rand against overseas currencies and elimination of the
diesel subsidy to farmers are the most important reasons. Trial
results indicated that input costs could be reduced when chemical
weed control is used together with mechanical weed control practices.
Furthermore, the results indicated that nitrogen levels should
be increased during wet seasons to compensate for nitrogen loss
through leaching and negative periods. Not burning stubble resulted
in higher yields during 1997.
V.L. Tolmay, G.J. Prinsloo, J.H. Hatting, and R. Maré.
The Small Grain Institute is implementing an integrated program
for control of the RWA. The basis of this program is the use of
RWA-resistant cultivars; natural enemies of the aphid and cultural
practices support these cultivars. Chemical control is intended
to be used only when extremely high infestation levels occur.
Six wheat cultivars with RWA resistance have been released by
the SGI for commercial production in South Africa to date. They
are Tugela-DN, Betta-DN, Gariep, Limpopo, Caledon, and Elands.
A backcross program will transfer RWA resistance to agronomically
acceptable lines for use in the winter and intermediate wheat
breeding programs. Resistant cultivars released for commercial
use are tested under field conditions, with and without chemical
control methods, to determine the value of these cultivars. All
resistant cultivars tested so far give yield and hectoliter advantages.
The parasitoid Aphelinus hordei is being released in the field
for the fourth year. More than 1.5 million individuals were released
on six farms in the Eastern Free State. Second-year field trials
with A. hordei show3e that this parasitoid is able to reduce RWA
populations significantly on both susceptible and resistant wheat
cultivars early in the season. Entomopathogenic fungi are being
investigated simultaneously for development as mycoinsecticides
against the cereal-aphid complex. Two hyphomycetous species, Beauveria
bassiana and Paecilomyces farinosus, are being screened for their
virulence against the RWA and other important cereal aphid species.
Techniques for mass production of suitable indigenous isolates
by both solid substrate fermentation and liquid fermentation are
being investigated currently. Field trials with an exotic strain
of B. bassiana (Mycotrol®) indicates that a commercial preparation
of this pathogen is capable of significantly reducing RWA numbers
on resistant wheat.
B.D. van Niekerk and O. Meintjes.
Leaf rust epidemics occurred in the Western and South Western
Cape during the 1999 season and possibly can be attributed to
the warmer weather early in the season and the susceptibility
of cultivars planted in these regions. Only two pathotypes were
identified, 3SA133, which dominated 95 % of the isolates, and
2SA140, comrising the other 5 %. Pathotype 3SA133 has virulence
to resistance genes Lr1, Lr2c, Lr3a, Lr3ka,
Lr10, Lr11, Lr14a, Lr20, and Lr24,
and pathotype 3SA140 has virulence to resistance genes Lr1,
Lr2a, Lr2b, Lr2c, Lr10, Lr14a,
Lr15, Lr17, Lr24, and Lr26.
Notwithstanding the dry conditions earlier in the season, severe
leaf rust epidemics occurred on barley along with the breakdown
in the resistance of the cultivar SSG 532, which has the resistance
gene Rph12. All South African barley cultivars are now susceptible
to leaf rust.
The major objective in preharvest-sprouting research is to
solve the problems experienced by the cereal producers and the
cereal industry. The major aims of this study are to characterize
newly released cultivars, determine their sensitivity to the environment
(G X E), and evaluate advanced breeding lines for their preharvest-sprouting
The eastern parts of the Free State especially were subjected
to heavy rainfall, and a considerable amount of wheat was lost
from preharvest sprouting coupled with low falling numbers. More
emphasis will be placed on falling number and a-amylase activity
F. van Niekerk.
Seed plays a vital role in the potential crop yield of each
small grain producer. Small grains must comply with the legal
requirements for purity and germination percentage before they
can be marketed. The Small Grain Institute now has an accredited
Seed Testing Laboratory where international methodology of the
International Seed Testing Association is used to determine the
quality characteristics of seed.
The demand for genetic-purity testing, determined visually,
has increased tremendously among seed companies and has accounted
for 662 tests in the past year. For cultivar identification, 27
samples, analyzed during the grading of small-grained seed in
accordance with the Southern African Grain Laboratory, resulted
in 472 tests by the laboratory. The germination and purity testing
over the past year resulted in 498 analyses, several of which
identified seed lots not complying with the South African Plant
Improvement Act. The laboratory provides a unique service and
has the infrastructure and experience to conduct seed analyses
objectively on a commercial and need-driven basis for the seed
A number of contracts were finalized with chemical companies
concerning the evaluation of seed treatments on wheat and maize.
This work contributed favorably to the income of the Seed Testing
Laboratory. The services were client-specific and extended the
commercial services of the laboratory.
Suzette Jordaan resigned from the spring wheat breeding program
at the end of March 2000. Felix Middleton was appointed as the
plant breeder in this program during January 2000. Robbie Lindeque
and Johan Smith resigned from the plant protection division. Kobus
van Zyl was married during December 1999.
UNIVERSITY OF STELLENBOSCH
Department of Genetics, Stellenbosch 7600, South Africa
G.F. Marais, F.L. Middleton, and A.S. Marais.
A triticale-breeding program for the winter rainfall region
was continued. No new releases were made, but promising advanced
lines were selected. Three advanced lines of Medicago polymorpha,
developed in collaboration with the company Agricol, were identified
for possible release. The first cycle of recurrent selection was
implemented in wheat. Large numbers of selected plants could be
intercrossed readily, making use of the dominant male sterility
gene Ms3 and a procedure for hydroponic culture of cut tillers.
Male-sterile spikes on selected plants were cut during flowering,
placed in a nutrient solution, and pollinated with spikes from
selected male plants. Pollen plants were discarded after 5-6 days,
and the female tillers kept in hydroponic culture for another
7-8 weeks when F1 seeds could be harvested. Seed set was approximately
70 %. Integrating recurrent selection steps in a pedigree-breeding
program with minimal additional input appears possible. The procedure
implemented involves different selection cycles for male and female
plants. F1 female plants are subjected to a single selection for
seedling resistance to leaf and stem rusts (mixed inoculum of
various pathotypes). In addition to F1 seedling screening, F2-F4
male families are selected in the field for disease resistance,
agrotype, and quality before being used in crosses.
Following the induction of allosyndetic recombination, four
Lr19-149 recombinants that resulted from proximal exchanges
were recovered. Recombinant Lr19-149-299 proved to be the
shortest. Another recombinant, Lr19-149-478, exchanged
a translocation segment distally from Lr19, which includes
the Wsp-1 locus. Plants heterozygous for recombinant translocations
299 and 478 were identified and are being test crossed in an attempt
to select double recombinants.
A DH-mapping population of approximately 90 clones was developed
from the F1 'Chinese Spring/PI1294994', and will be used in an
attempt to map certain chromosome 7DL loci in relation to the
Attempts to find molecular markers associated with chromosomes
having genes for salt tolerance were continued making use of F1
'Th. distichum/4x rye//2x rye' plants (generally having
20-22 chromosomes) and B2F2 'triticale//Th. distichum/2*triticale'
derivatives. Preliminary results indicate that more than one chromosome
may be involved. Eleven putative disomic additions of unknown
Thinopyrum chromosomes to triticale have been derived.
Backcrosses to transfer leaf and stripe rust resistance from
several Triticum species to common wheat were continued.
Chromosome locations of two leaf rust resistance genes from T.
turgidum subsp. dicoccoides (on chromosomes 2B and
6B) and one gene from T. timopheevii (chromosome 2B) have
been determined. Further genes from these two species as well
as Ae. speltoides, Ae. kotschyi, Ae. peregrina,
Ae. sharonensis, and Ae. columnaris appear to have
been integrated into wheat chromosomes and are being used in monosomic
analyses to determine the chromosome involved.