INSTITUTO DE CIENCIA Y TECHNOLOGIA AGRICOLAS ICTA
Programa de Trigo, Guatemala, Central America.
Valentin Azanon, Rene Mora, and Fernando Aldana.
During 1995, the wheat program in Guatemala evaluated
germplasm in all stages of development. In the Advance Nursery,
the ELITE, we evaluated 64 entries. Five percent of the ELITE
came out of national germplasm from crosses made in Guatemala,
23 % from CIMMYT segregant material selected in Guatemala, and
72 % from advanced lines that came to our program in different
CIMMYT nurseries. In the ELITE, the highest yielding line was
from the cross `Kaus//VEE 5/SARA/3/VEE 5/SARA', with
a mean of 4.97 t/ha. In the pedigree of this line, two national
cultivars Vee 5 (Olintepeque 83) and Sara 82 participated in a
cross with a high yielding CIMMYT line, Kaus.
At the same time, in the ENTRI (National Nursery
of Wheat), we evaluated in the farmers' fields the best
lines from the ELITE in 1994. This nursery has fewer entries.
In 1995, there were 10, including the farmers' best cultivar.
In this nursery, the highest yielding line was `PP/ALD/SARA/3/VEE
`S'', with a mean of 4.50 t/ha. This line also
has a sister of Olintepeque 83 and Sara 82 as a parent. These
results confirmed the presumption that local `best x best'
crosses, with a top cross, with a high-yielding line could develop
high-yielding local germplasm. The most stable cultivar in the
ENTRI was Cumpale; the newest cultivar release in the country.
During this year, farmers were paid on the basis
of test weight. The prices for a 100 pound bag were, US $9.33
for 65-69 kg/hl wheat, US $9.66 for 69.1-73 kg/hl
wheat, and US $9.83 for more than 73 kg/hl wheat. The price for
100 pounds of flour was US $22.50.
The consumption of wheat products is increasing in
the country, especially in the urban areas. Ten years ago, people
did not consume wheat flour tortillas, because tortillas made
from corn are the most popular in our country. However, because
wheat flour tortillas now can be produced industrially, and their
price is equivalent at US $0.03 per tortilla, they are gaining
popularity and their consumption is increasing.
AGRICULTURAL RESEARCH INSTITUTE OF THE HUNGARIAN ACADEMY OF SCIENCES
Martonvásár, 2462, Hungary.
Breeding.
Z. Bedő, L. Szunics, L. Láng, O. Veisz, Lu. Szunics, I. Karsai, Gy. Vida, and K. Mészáros.
Two new winter wheat varieties are expected to be
registered in the spring of 1996. `Mv Madrigal'
(Mv DH 217-92) is a dihaploid developed in anther culture
from the combination `Mv 16-85/Bu 20.' The cultivar
is an early-maturing wheat with excellent winterhardiness,
recommended for production on growing sites with average or below-average
yield levels because of its medium plant height and good adaptability.
Mv Madrigal has average protein content and good baking quality
and is completely resistant to stem rust and moderately resistant
to powdery mildew and leaf rust.
`Mv Magdalena'
(Mv 215-92) is a medium-late variety developed from a cross between
high-quality parents (Yubileinaya 50/F 29//Mv MA), giving it a
high wet gluten content of over 35 % and good baking quality.
In the field. Mv Magdalenat is resistant to stem rust, leaf rust,
and powdery mildew. Because of its good lodging resistance and
adaptability, this cultivar can be grown on good and poor areas
alike.
Resistance studies. The
changeable weather experienced during the 1994-95 farming year
promoted fairly severe attacks by several diseases, the consequence
of which was a lower wheat yield than expected.
As in 1994, a nationwide leaf rust (P. recondita)
epidemic occurred in 1995. By the third week of June, the leaves
of susceptible varieties were covered completely with rust, because
a significant proportion of cultivated varieties bear the Lr3
or Lr26 resistance genes, to which the pathogen population
is now virulent. In field experiments with artificial inoculation,
resistance genes Lr9, Lr19, Lr23, Lr24,
Lr25, Lr27, Lr33, and Lr37 were found
to offer satisfactory protection against leaf rust. Yellow rust
(P. striiformis) is a pathogen not often encountered in
Hungary. Nevertheless, similar to last year, it was observed at
various places in the country in late April and early May, after
which it spread and infected the majority of varieties. Varieties
in Hungary have not been bred for resistance to this pathogen.
For many years, thanks mainly to the excellent biological protection
provided by the resistance genes Sr31 and Sr36 that
were incorporated into the varieties, no stem rust (P. graminis)
epidemic has occurred. The pathogen also is avirulent to genes
Sr9b, Sr11, Sr21, Sr24, and Sr37.
Wheat powdery mildew (E. graminis) caused
only a moderate epidemic. The major known resistance genes do
not provide sufficient protection, because the pathogen has become
virulent to them. In greenhouse experiments on the test assortment
compiled by November, 25 races were identified. The prevalent
races and their frequencies were as follows: 51 (20.5 %), 72 (20.0
%), 90 (19.1 %), 46 (7.1 %), and 70 (6.7 %). The number of virulence
genes per race was 5.37.
In 1995, climatic factors during heading were favorable
for the spread of Fusarium fungi, but a late May heat wave
prevented mass multiplication of the pathogen. The large quantity
of precipitation in the first half of June and frequent gales
led to lodging in many wheat fields. As a consequence, severe
Fusarium infection of wheat was observed in places. All
the cultivated varieties are sensitive, though they differ in
the degree of susceptibility.
Without seed treatment, bunt (Tilletia spp.)
would cause considerable damage, because none of the registered
varieties are very resistant. The majority of varieties are susceptible,
with only a small proportion having moderate resistance. After
artificial inoculation, genotypes containing resistance genes
Bt8, Bt9, and Bt10 proved to be resistant.
Plants infected with bunt had poorer frost resistance than healthy
plants. This difference was significant for the majority of cultivated
varieties and for lines with known resistance genes.
The majority of wheat varieties recently bred in
Martonvásár have good resistance to powdery mildew
and leaf rust (Mv Palma, Mv Vilma, Mv Magma, and Mv 25), and almost
all of them have excellent stem rust resistance. They provide
simultaneous resistance to a number of pathogens and, thus, serve
as the basis for biological plant protection.
Under artificial (greenhouse) and field conditions,
the oat varieties used in crosses were evaluated for crown rust
and powdery mildew resistance; the extent of Fusarium infection
also was investigated. Moderately resistant and resistant varieties
were found for all three pathogens. These resistant sources will
form the basis for the development of varieties suited to low-cost,
environmentally sound cultivation.
Frost-resistance studies.
Over the last year, studies were made on the frost resistance
and winter hardiness of varieties and lines of rye, wheat, triticale,
barley, durum wheat, and oats. Taking advantage of the research
facilities available in the phytotron, mean frost-resistance levels
of the various species were determined. The results indicate that
considerable differences occur among the cereal species. Rye is
the most frost resistant, followed in decreasing order by wheat,
triticale, durum wheat, barley, and oats. As the result of targeted
breeding for this trait, the winter hardiness of the Martonvasar
wheat varieties is excellent. The frost resistance of the new
winter durum wheat lines is better than that of the best winter
barley varieties and, in some cases, exceeds that of the winter
wheat variety Bankuti 1201.
Observations were made on four occasions (in early
December, January, February, and March) in field experiments to
determine changes in the dynamics of winter hardiness in various
cereals. The winter cereals achieved maximum hardiness in January,
after which the value declined gradually until early March.
Studies were done in a phytotron on the effect of
increasing atmospheric CO2 concentrations on the hardening process
in young plants. An increase in the CO2 concentration from 350
ppm (measured under natural conditions) to 700 ppm had a favorable
influence on the hardening process, so that more plants survived
than under normal conditions. During preliminary growth, measurements
were made on leaf area, mass, and total biomass production of
the plants. In all the varieties, an increased atmospheric CO2
concentration led to an increase in leaf area and biomass; the
difference was significant for the varieties Alba and Presto.
Simulation of climatic changes.
Experiments were conducted last year in a phytotron to study the
effects of climatic changes on the development of young cereal
plants and on yield components. When averaged over 14 varieties,
doubling the atmospheric CO2 concentration to 750 ppm gave a significantly
higher yield primarily because of an increase in the grain number.
The difference in 1,000-kernel mass was not significant when averaged
over the 14 varieties. With the exception of three varieties (Fredrick,
Bezostaya 1, and Hordeiforme 1443) the grain yield was higher
for plants raised in an atmospheric CO2 concentration of 750 ppm,
and this difference was significant at the P = 1 % level for varieties
Alba, Presto, and Kompolti korai.
B. Barnabás, G. Kovács, I. Takács, Z. Pónya, É. Szakács, and I. T'már.
During the last year, our activity mainly focused on three different fields of plant biotechnology.
Exploiting an efficient in vitro androgenic system
for wheat. A large number of induced microspore-originated
embryos were used as targets of biolistic DNA transfer. To elaborate
an efficient haploid transformation system, first, histochemically
detectable and herbicide- resistant marker genes, such as uida
and bar gene constructs, were introduced into the young
haploid embryos. These embryos seemed to be suitable targets,
similar to young zygotes, for foreign gene transfer, especially
if plants could be regenerated directly from them on a selective
regeneration medium. Foreign gene integration was studied using
PCR techniques for T0 and T1 plants.
Wheat anther culture.
Introduction of colchicine under selective culture conditions
(50 and 100 µM Al at pH 4.5) in wheat anther culture resulted
in a selected microspore population of varieties that developed
directly into a DH progeny having an improved aluminum tolerance.
This technique will allow us to produce doubled haploid plants
resistant to other metal ions such as cadmium and zinc. The physiological
effect of the stress factors on in vitro androgenesis and the
process of DH plant regeneration is studied using protein analysis
techniques. The possible accumulation of metal ions in the microspores
or calli is examined by X-ray microanalysis.
Confocal scanning microscopy.
Detailed cytological and histological studies using confocal laser
scanning microscopy, were made on various Triticum species
with diverse ploidy levels to follow the male and female gametophyte
development in vivo and in vitro. An asynchronity was detected
in all species between the in vivo and in vitro developments of
the pollen and the embryo sac. The speed of cell development and
formation of mature gametophytes was highest at the hexaploid
level. A considerable difference occurred between the volume of
the embryo sac of the 8-cell stage in the different Triticum
species (T. aestivum, T. araraticum, and T. monococcum).
These observations supply the necessary information about the
developmental processes of the gametophytic cells for the in vitro
fertilization studies.