8024 Telegraph Rd., Bloomington, MN 55478,
USA.
Robert W. Romig.
Despite a few growing pains and untimely
rain that affected some planting operations, we successfully transferred
winter wheat segregating populations between the Northern and
Southern Hemispheres this year. We had a relatively successful
nursery in Argentina that was planted in early June with seed
harvested in the U.S. in early May. Selections harvested there
in late November were planted in south Texas in mid-December,
where they are growing well.
We had good germination in the straight
winter populations harvested in Argentina. Presumably, a couple
of cold-shock cycles prior to planting, each lasting 2 days at
below freezing temperatures, were adequate to break any germination
dormancy that may have been present. We have our fingers crossed,
hoping that these will be vernalized to produce seed this spring.
The real proof of the usefulness of this `shuttling
concept'
will be if we can successfully repeat the cycle this year.
Our crossing program in Chile turned
out well again. However, we experienced a delay in receiving
the seed because of a delivery mix-up in Miami. Consequently,
the F1s were planted a bit later than expected. Germinated
seeds from the `winter
x winter'
crosses are being chilled under refrigeration to develop vernalized
F1 seedlings for transplanting later this spring.
This year's program currently consists
of a nursery in Texas that has segregating lines and winter and
spring wheat trials and a nursery near Yuma, AZ, with new F1s,
segregating lines derived from last year's nursery in Minnesota
along with a number of wheat and triticale increase plots. Work
is in progress to establish spring wheat trials this year near
Moses Lake, WA.
We have changed the organizational
basis of the company this year (1995) from a sole proprietor enterprise
to a limited liability company. This is a relatively new type
of organization that offers certain useful financial protection
features for small business organizations such as ours. However,
we continue to follow the original operating and breeding strategies,
reported in last year's Newsletter.
Our business strategy is evolving.
The central concepts are to be a provider of improved wheat genetics,
to bring these to market by working through local or regional
producers/marketers, and to form synergistic alliances with other
breeding programs.
Institute of Biological Resources
Castelar, Argentina.
Chromosome mapping: comparison between
recombination frequency values of centromeric genes obtained by
using telocentric and normal chromosomes.
G. Tranquilli, L. Pfluger, S. Lewis,
and E. Suarez.
The telocentric lines developed in
Chinese Spring by Sears have been very useful tools in chromosome
mapping, mainly in gene location on specific chromosome arms,
as well as their linkage with the centromere. Nevertheless, it
was proposed (Sears 1972) that the chromosome pairing in the centromere
proximal area and, consequently, crossing over, are reduced in
a heteromorphic bivalent. Therefore, the obtained recombination
frequency in these cases is lower than that expected when normal
bivalents are present. In order to analyse this situation, the
recombination frequencies of two centromeric genes, one on each
chromosome arm of 6B, are being evaluated using both telocentric
or normal chromosomes.
The considered marker genes are Amp-B1
(aminopeptidase) on 6BS and B2 (awn inhibitor) on 6BL.
The Argentinean cultivar Sinvalocho MA carries a silent allele
for Amp-B1 and the b2 allele (awned). On the other
hand, Chinese Spring codifies for Amp-B1 and possesses
the B2 allele (awnless). Chinese Spring (euploid) and
its double ditelocentric line for chromosome 6B were crossed with
the 6B substitution line of Sinvalocho MA (Sin) into Chinese Spring
(CS(Sin6B)). Both F1s (2n = 42 and 2n = 41 + t6BS
+ t6BL, respectively) were backcrossed with CS(Sin6B), and the
resultant offspring classified according to the following: karyotype,
aminopeptidase pattern, and presence or absence of awns. A total
of 140 and 188 individuals corresponding to each BC1,
respectively, have been evaluated. In the "telocentric chromosome
system", individuals with abnormal karyotypes were taken
into account if they could be classified unambiguously as parental
or recombinant type. Up to the present, no recombinant has been
found considering Amp-B1 and the centromere. On the other
hand, for the B2 locus, a further generation will be obtained
in order to classify unambiguously the gene expression, because
many plants, from both BC1s, showed an intermediate
phenotype for awn expression.
Reference.
Sears E. 1972. Reduced proximal crossing-over
in telocentric chromosomes of wheat. Genet Iber 24:233-239.
Genetic variability of an Argentinean land race of wheat
E. Suarez, M.L. Appendino, G. Tranquilli,
and L. Bullrich.
Through the evaluation of a wheat land race grown by a farmer in the province of Catamarca (Argentina), nine lines were isolated showing variation for the following features: grain colour (from white to dark); glumes (pubescent and glabrous); awnedness (awned, semiawned, and awnless); Erysiphe graminis tritici reaction (susceptible and resistant); ear emergence time (an extreme difference of 15 days, for plants cultivated in long days); coleoptile (purple and green); and plant height. This last character (plant height) showed a range of variation of about 50 cm, a difference similar to that observed between semidwarf and tall varieties carrying Norin genes. Nevertheless, all lines were responsive to gibberellic acid. The results for these eight traits showed a high potential of genetic variability, even for characters not necessary present in commercial cultivars.
On the other hand, when the nine lines
were isoenzymatically assayed, no variability was found for IBF
(iodine binding factor), a very polymorphic system among commercial
cultivars.
College of Agriculture, P.O. Box 509, Cordoba,
5000, Argentina.
Biological yield, harvest index, and
ear weight as indirect selection criteria for grain yield in wheat.
W. Londero, V. Pantano, F. Bidinost,
D. Bonelli, R. Roldon,
and R. Maich.
The objective of this study was to
determine the effect of indirect selection for grain yield using
biological yield (BY), harvest index (HI), and ear weight (PSP)
as selection criterion. During 1990, 160 crosses (single and
double) in the first selfing generation were cultivated at Ferreyra
(Cordoba).
A random sample of 800 S1 plants was taken from them
and characterized through BY, HI, and PSP. For each selection
criteria, a group of 15 S1 superior plants was created.
At the same time, the best 15 were selected according to the
phenotypic value (Ph). The 60 S1 derived lines were
evaluated for grain yield with two sowing dates (May and June)
during 3 years (1991/92/93). Analysis of variance of the experiment
was conducted according to the factorial model. Nonsignificant
differences were obtained among criteria, but a significant (P
< 0.05) `selection
criteria x sowing date'
interaction existed. For the first sowing date, the material
selected for Ph yielded more than the HI selections. For the
second, the material selected for BY performed worse than those
selected for Ph and HI.
Correlated response to recurrent selection
for grain yield in wheat.
F. Salvagiotti, N. Conton,
C. Ferraris, B. Ferro, C. Olmos, and R. Maich.
The objective of this work was to measure
the efficiency of a recurrent selection program for grain yield
and to determine the effect on associated characters. During
1993, 54 S1:2 lines, 17 from each selection cycle (C0,
C1, and C2), were evaluated at Ferreyra
(Cordoba)
for two sowing dates (May and June) and without replication per
date. Grain yield (GY), biological yield (BY), and harvest index
(HI) were recorded for each plot. Nonsignificant differences
were obtained among cycles for GY and BY, but not for HI. For
HI, the C1S1:2 and C2S1:2
lines showed higher values than C0S1:2.
The C1 and C2 group mean differences were
not significant.
R. Maich, P. Daher, and M. Bianchi.
A networking point of view and farmer,
technician, and contractor interactions are responsible for the
success of agriculture in marginal areas. To make the reconversion
effective, the farmer must choose suitable cultivars and farm
practices, the technician must put more emphasis on his plant
breeding programs, and the contractor must provide capital for
technological development.
Influence of early-generation selection
for proteins on yield and bread making quality in wheat.
G. Manera, Z. Gaido, and M.E. Dubois.
The lack of wheat that meets millers'
specifications in the central semiarid region of Argentina indicates
the necessity to promote the development of materials adapted
to great fluctuations in rainfall. These materials should have
high potential production, stability in yields, and good commercial
and industrial characteristics. The objective of this work was
to study the effect of early generation selection for high protein
content on yield and bread making quality in wheat grains available
for the semiarid region. Yield and bread making quality measured
as proteins (P), humid gluten (GH), dry gluten (GS), and mixogram
(M) was determined in 45 lines of wheat. These lines, selected
in the F3 generation for high protein content (selection
pressure = 15 %), came from three selection environments (semiarid,
intermediate, and humid), reproduced in the semiarid. No significant
correlation occurred between protein content and yield in any
of the three studied environments; all resulted in good bread
making quality (xP = 14.42; xGH = 35.08; xGS = 13.13; and xM =
6.33). These results indicate the convenience of simultaneous
selection in early generations, for yield and protein content
in wheat grown for semiarid regions.
Ana L. Pascualides, S. Patricia Gil,
Maroa
M. Cerana, and Laura Gonzolez.
The goal of this study is to determine
the anatomical adaptations of the flag leaf blade in Triticum
aestivum L. varieties to different, local, environmental
conditions. The commercial varieties, PROINTA Oasis and Las Rosas
INTA, and the experimental ones, T7 and T24, were sown in plots
of 11 m x 45 m at two different spacings in the row (15 cm and
30 cm) late in the season. A random design with factorial treatment
was used for this test. Temporary slices of the abaxial and adaxial
leaf epidermis were made in order to characterize them and to
calculate the stomatal frequency (SF), the stomatal index (SI),
the frequency of silico-suberose pairs, and the frequency of prickles
(PF). A further analysis shows that the distance factor does
not influence the variables for the abaxial face. But, in the
adaxial face, both SF and PF are influenced by distance, whereas
the SI does not change. The number of stomata/mm2
increases at 15 cm spacing for every cultivar, except PROINTA
Oasis, which has a different behavior. The same trend occurs
with PF.