Twenty Six Years of Wheat Breeding Activities at IAPAR

The description of the IAPAR wheat breeding program in its 26th years of existence aims at presenting its major achievements giving an idea of the program size, breeding objectives and methodology. A germplasm flow chart will show the steps by which the populations have to follow starting either from crosses or from introductions until an advanced inbred line can be evaluated and elected as a new cultivar. A list of 23 wheat cultivars released by the program along with their pedigrees is presented as a special contribution. From the recent developed cultivars, data on grain yield, agronomic characteristics, technological quality and kernel properties are presented. The pedigree description for IAPAR 53 and the development of IPR 85 are presented in some detail. New biotechnological tools to help wheat breeding become more efficient are discussed.


INTRODUCTION
Wheat (Triticum aestivum L.) is one of the largest consumed cereal by human kind, representing approximately 32% of the world grain production.Its unique combination of proteins and capacity to produce light leavened and tasty products makes it very attractive to the consumers.It was probably the first cereal to be domesticated and cultivated favored by the possibility of long term storage.
In Brazil, wheat has an important participation in the population diet and the consumption has increased with the urbanization process.Although the country has extensive areas suitable for the wheat production, it is the second largest importer of the cereal in the world.Nowadays we are import 75% of our consumption which totals 9.5 million tons.This makes us dependent on this important staple food that needs to be produced in other countries.With the creation of MERCOSUL, wheat has become a trade issue with other countries, especially with Argentina.Our economy has been strongly affected by this reality.Good part of the capital spent with importation could be used to stimulate regional economy (Hubner, 1999).
The state of Paraná is the largest wheat producer of Brazil, contributing with 60-70% of the total production.The average yields range from 1.7 to 1.9 tons.ha - .The IAPAR Wheat Program nowadays known as the Winter Cereals Program, started in 1973 with the introduction of nearly 5,000 genetic entries, development and selection of hybrid populations and carrying out yield trials to obtain adapted cultivars to the varying climatic and soils conditions of Paraná state.In 1976, the Wheat Program was expanded by a partnership with Embrapa Trigo and COODETEC (before CNPTrigo/Embrapa and OCEPAR, respectively).This new partnership gave rise to the Integrated Plan of Wheat Research in Paraná, from which resulted in an annual indication of several cultivars, sowing dates, and subsidies for the new wheat crop regionalization in the state (IAPAR, 1984).
Since then, several technologies have been developed for soil management, the establishment of criteria for tolerance to acid soils as a parameter for cultivar indication, the integrated management of diseases and insects, adequate sowing dates, rational use of fertilizers, and crop rotation.The continual development of new technologies according with actual needs has also been emphasized.The state cultivar evaluation through the regional yield trials network is still done in cooperation with the partnership mentioned earlier.Although, the breeding programs are conducted separately by each institution.
The process of developing cultivars is long and costly, taking approximately 10-12 years to breed and disseminate a new cultivar.The use of new biotechnologies such as molecular markers (Riede and Anderson, 1996) and the production of double-haploids (Scheeren et al., 1999) might contribute to increase the efficiency and reduce the time for new developments.
IAPAR´s research program has made 23 wheat cultivars available to farmers which are appropriate to different regions in Paraná and also to some regions in Mato Grosso do Sul and São Paulo.

BREEDING PROGRAM
The IAPAR wheat breeding program, in its 26 th years of existence, makes annually hundreds of crosses between adapted cultivars and sources of necessary traits for the cultivation and industrialization of the new wheat.The state of Paraná is located in a transitional zone as far as climate and soil properties are concerned.This makes the breeding tasks more difficult, requiring sometimes the development of more regionally adapted cultivars in order to be more competitive and superior to the ones being presently used.
In the last years, quality has become paramount and dependent on the segment, which is involved in the production.To the farmer, superior quality is represented by desirable agronomic characteristics such as high yield potential with good hectoliter weight, good resistance to diseases, which results in economic profitability.To the miller, however, quality means uniform kernels with high flour extraction, and low ash levels.As for the baker, the flour must have high water absorption, good mixing tolerance, average gluten strength and high protein content, which represent balanced factors with potential to produce bread with good rheologycal characteristics.Finally, to the consumer, the last element in the production chain, the concept of quality embraces a larger issue in which palatability and appearance of the elaborated products are fundamental.In each case, it is expected that the desirable wheat will produce a bread with high volume, adequate external and internal texture and high nutritional value.
Breeding for technological quality is an important objective of any project aiming at developing new cultivars suitable for the milling and baking industry as well as at supplying flour suitable for other products such as pasta, crackers and cookies.

RESEARCH OBJECTIVES
The major objectives of wheat breeding for the state of Paraná are listed below: 1. Breeding for yield increase • Yield components (heads/m 2 ; kernels/ head; kernel weight; etc)

BREEDING METHODOLOGIES
Breeding methodologies such as "pedigree", "modified pedigree" or "modified bulk" have been used in the research program, with selections in both acid and non-acid soils.Selection of plants and breeding lines followed by Preliminary yield trials have been carried out in Londrina (Region 6 -North), in Palotina (Region 7 -West), and Ponta Grossa (Region 8 -South) of the state of Paraná.A network team has evaluated recommended and potential new cultivars in approximately 10 locations on different seeding dates.
Every year a Crossing Block is established in which the potential parental genotypes are grouped according to their major traits.120 entries, approximately, are grouped in the following major sub-blocks: 1) Yield potential; 2) Aluminum tolerance; 3) Technological quality; 4) Preharvest sprouting resistance; 5) Sources of leaf rust resistance; 6) Sources of mildew resistance; 7) Sources of leaf blight resistance; 8) Sources of fusarium head blight.
Either individual plant or bulk selections are performed on outstanding populations (within and between families) until homozygosity is achieved.Homozygosity increases by 50% in each inbreeding generation as wheat is a self-pollinated crop.Advanced lines are nominated as follows: lines IA are obtained from germplasm introductions; lines LD are lines originated from crosses and/or segregating generations selected in Londrina; and lines PG are lines developed in Ponta Grossa.The germplasm flow in the breeding program can be seen in the diagram named Germplasm Flow Chart (Figure 1) which illustrates all the major steps of a particular cross or selection until the advanced lines can be cut and evaluated in yield trials.Quality tests and seed increase are performed according to the stage the lines have reached in the program.

RECENT CULTIVARS
Yield comparison of the major recent cultivars indicated and adapted for cultivation in regions 6 (North), 7 (Central-West) and 8 (South) of Paraná in the four last years can be visualized in Figures 2  to 4. The recent cultivars are moderately tolerant to soil aluminum toxicity, an important requirement when a wider adaptation is sought as is the case of this program.The classification of the Brazilian wheat cultivars for aluminum toxicity in acid soils can be found in Sousa, 1998.Major agronomic characteristics of presently grown wheats can be observed in Table 2. Crop Breeding and Applied Biotechnology, v. 1, n. 1, p. 60-71, 2001

2001, Brazilian Society of Plant Breeding
The cultivars developed by the Wheat Project from 1980 to 1999 are presented in Table 1. 1/ Indicated for soils with aluminum saturation higher than 5% (maximum 35%). 2/ Indicated for soils with aluminum saturation higher than 5%.
Crop Breeding and Applied Biotechnology, v. 1, n. 1, p. 60-71, 2001    Breeding for quality is an important priority of the project that aims at developing new cultivars suitable for the industry.Thus, the milling, bakery, pasta and cookie sectors can be supplied with appropriate flour to every product so the consumer will have diversified products.The classification of cultivars presently in cultivation is presented in Table 3.
Approximately 38% of the several seed classes available for cultivation in the year 2000 which are certified by APASEM (Paraná Seed Growers Association), are cutivars from IAPAR.Some Crop Breeding and Applied Biotechnology, v. 1, n. 1, p. 60-71, 2001 Table 3 -Technological quality of wheat cultivars developed by IAPAR, according to the percentage class distribution and rheologycal analysis of samples.
1/ W is the Alveograph value and STB 2/ is the Farinograph Stability, both measure the gluten strength.FN 3/ indicates the Falling number, which is related to the preharvest field sprouting. 4/ Improver: excellent quality; Bread: good quality; Soft: weak gluten.important kernel characteristics of IAPAR cultivar´s which can help in the choice of material do be sowed, are presented in Table 4.    Two recent cultivars will be described in some detail, to show the pedigree management in the program, as well as the selection history of the populations.

PEDIGREE OF IAPAR 53
IAPAR 53 was derived from a simple SULINO/ IA 7929 cross .The pedigree of the two parental genotypes are described below according to Purdy et al. (1968).
The genetic contribution of each genotype to the pedigree of IAPAR 53 can be observed in Figure 6.
It can be seen that IAPAR 53 has a major genetic contribution from Mexico-CIMMYT (59.4%), but also expressive contributions from Chile, Brazil and USA.In Figure 6, the importance of pedigree maintenance in tracing back the genetic contribution of parental genotypes and in the planning of future crosses to combine new sources of adaptative traits is shown .

Development of IPR 85 wheat
1. Genetic Origin: The cultivar IPR 85 was originated from a simple cross between IAPAR 30 and Trigo BR 18 -Terena made in 1987.The pedigree is described below: 2. Breeding Method: The breeding method used was the Modified Pedigree, with annual selections of individual plants or bulks according to generation and the field conditions, taking into consideration the biotic and abiotic stresses.
3. Description: 1987 -Year in which the cross was done; IP 8966 is the cross number; 1988 -Generation F 1 : mass selection in two rows of 2 m length; 1989 -Generation F 2 : third individual plant, selected from a 10.0 m 2 plot in Londrina (L) 1990 -Generation F 3 : bulk selection from a 5.0 m 2 plot; 1991 -Generation F 4 : bulk selection from a 5.0 m 2 plot; 1992 -Generation F 5: third individual plant, selected from a 5.0 m 2 plot; 1993 -Generation F 6 : mass selection of the population; 1994 -Agronomic evaluation in augmented design; Crop Breeding and Applied Biotechnology, v. 1, n. 1, p. 60-71, 2001 SON  1996 -Regional Yield Trial in 10 locations;1997 -First Final Yield Trial in 10 locations;1998 -Second Final Yield Trial in 10 locations;1999 -Release and Registration of Cultivar IPR 85;2000 -Breeder's Right Protection (Temporary Protection Certificate Nº 00194).
The average grain yield for two adaptation regions in three years as well as the quality evaluation of IPR 85 are presented in Tables 5 and 6 respectively.(Riede et al., 1999).

NEW BREEDING TOOLS
New biotechnogical techniques such as haploidy, which uses wheat x maize crosses (Laurie andBennett, 1988 andScheeren et al., 1999) or microspore culture (Kasha et al., 1998), marker assisted selection (Langridge and Chalmers, 1998;Dubcovsky, 1998 andAnderson, 1998), and transformation (Barcelo et al., 1998 andPellegrineschi, 1999) are here to help speeding up breeding programs, in making indirect selections more efficiently and in transfering genes from other species, breaking up the sexual crossing barriers.
The new generation of plant breeders have to be able to understand and manipulate these new molecular tools in order to make further improvements in the cereal crops.

Figure 1 -
Figure 1 -Management steps in the cultivar development procedure.

Figure 4 .
Figure 4. Average grain yield (kg.ha -1 ) of wheat cultivars from IAPAR, period of 1996-99.Adptation Region n o 8 After the enforcement of the Plant Breeder's Right Law in Brazil, the new cultivar registration will need to have a Value of Cultivation and Use (VCU) determination to ensure the seed commercialization in the country.If a cultivar protection is pursued, than a more complete cultivar descriptors form will be required from the SNPC -National Service for Cultivar Protection, associated with the Secretary of Agriculture and Provision.Regarding to cultivar indication to farmers, the state of Paraná has been divided in three major adaptation regions according to climatic and soils properties (Figure5).

Figure 5 -
Figure 5 -Adaptation regions for the Cultivation and Use Values for Wheat in Paraná.

Figure 6 -
Figure 6 -Gene pool contribution to the development of IAPAR 53.

Table 4 -
Kernel characteristics of wheat cultivars developed by IAPAR.

Table 5 -
Average grain yield in kg.ha -1 and percent relation to the checks in three years and two Adaptation Regions of Paraná State.

Table 6 -
Technological Quality evaluation of cultivar IPR 85.