Selection for grain yield and quality in segregating generations of wheat

Selection for Grain Yield and Quality in Segregating Generations of Wheat

Alessandro Ramos de Andrade¹, Carlos Roberto Riede2^*, Maria Brígida dos Santos Scholz², Deonisio Destro¹ and Ines Cristina de Batista Fonseca¹

1Departamento de Agronomia da Universidade Estadual de Londrina (UEL), C. P. 6.001, CEP 86051-990 Londrina-PR, Brazil; ²Áreas de Melhoramento e Genética Vegetal e Ecofisiologia do Instituto Agronômico do Paraná (IAPAR), C. P. 481, CEP 86001-970 Londrina-PR, Brazil

ABSTRACT

The objective of the work was to combine simultaneous selection for grain yield and technological quality in elite segregating populations of wheat developed by the breeding program of IAPAR. Thirteen populations were chosen according to their potentiality of genetic variability in the F₂ generation of the 1997 crop season. One hundred heads were selected from each population and sown as F₃ head-rows in the following season. Visual selection of individual head-rows or lines was done for yield potential and maturity. Seeds of the selected lines were evaluated for Sedimentation Values as well as Protein Content. The populations were identified as C1 to C13, representing the different crosses. The number of F_2:3 lines selected within populations varied from one to 12. The populations C6, C7, C9, and C13 were classified as early maturity. Two populations (C6 and C9) presented higher potential for grain yield. The populations C12, C3, C8, and C1 were better for mean and variance of sedimentation values. The populations C2, C3 and C11 had a good performance for mean, maximum values and variance of protein content. The data indicates a good potential to obtain advanced lines with higher grain yield associated with a better technological quality.

Key words: Triticum aestivum, technological quality, grain yield, segregating generations

INTRODUCTION

The sectors involved in the production, trading and industrializaton of wheat (Triticum aestivum L.) are interested in several aspects of its quality. The need of quality wheat grain that fulfills the requirements of the industry, and the fact of Brazil not being self sufficient in production, increases the demands of breeding programs which can obtain improved cultivars with better grain quality associated with higher grain yield.

The purchase of wheat by the milling industry considers aspects of technological quality such as general gluten strength, which can be measured by different methodologies, allied to the fact of the grain not being affected by pre-harvest sprouting caused by excessive precipitation after grain maturation. The rain during the harvest operation stimulates the activity of the enzyme a-amilase, which initiates the starch degradation, reducing the possibility of baking bread and other products (Guarienti, 1996).

Sedimentation values correlates strongly with the general gluten strength and bread making as pointed out by Zeleny (1947). A modification of a test for rapid estimation of gluten strength in durum wheats was described by Dick & Quick (1983). A modified sedimentation test was also performed by Peña et al (1990), to find associations of quality characteristics and the presence of 1B/1R translocation wheats, indicating the exchange of chromosome segments between wheat and rye which normally reduces the overall wheat technological quality.

Many quality traits although affected by environmental factors, are under genetic control, which allows manipulation and selection by the breeders (Lukow & McVetty, 1991). The technological quality of wheat grain presents a strong relation with the total protein content, which by its turn is responsible for other physical parameters of the industrial processing of wheat (Preston et al, 1995). The selection for the improvement of several simultaneous traits in autogamous plants is a difficult task, considering the complexity of the genetic basis involved, the need of large size populations for selection, the need of several recombination cycles and the difficulty of environmental control that can interfere with the phenotypic expression of the traits. Considering all the above, the genetic progress obtained with the selection of a unique individual with all the desired traits becomes a very hard task for the plant breeders. It becomes important to develop systems to conduct segregating populations, which increases the efficiency of better genotypes identification (Jensen, 1988).

According to Allard (1960), the selection systems, which have shown efficiency in self-polinated crops can be grouped in pure-line and mass selection. These systems are usually used combined with different breeding methods namely: pedigree method in which individual selections are made until the fixation of characters and bulk method based on natural selection. Variations of these methods like backcrosses, single-seed descent and recurrent selection are used less extensively (Fehr, 1987; Destro & Montalván, 1999).

Considering the increasing interest of industrials, farmers and breeders in evaluating the quality of wheat for several uses, the objective of the present study was to obtain advanced lines with higher grain yield associated with a better technological quality of the grain.

MATERIALS AND METHODS

The F₃ populations were planted in the 1998 crop season at the Experimental Station of IAPAR in Londrina-PR, using seeds originated from parents with a large variability for grain yield, environmental adaptation and technological quality (Table 1). One hundred individual heads (spikes) of each of the thirteen F₂ populations were harvested in the previous year. Each harvested head in the F₂ generation gave origin to a 1 m long F₃ line. In this regard, each F₃ population consisted of a 100 head-rows. One check cultivar was placed every 20 head-rows. The checks were 'IAPAR 29-Cacatu', 'OCEPAR 16', 'Trigo BR 18-Terena' and 'Trigo BR 23'.

The germplasm used in the crosses which were considered source of genetic variability for quality were: CDC TEAL, GRANDIN, ND 674, IAPAR 6, CULIACAN, AMIDON, GLUPRO, AC MINTO, and AC DOMAIN, which were introduced mainly from the United States, Canada and Mexico. The other genetic materials used in the crosses are adapted to the Brazilian environmental conditions.

The observations of agronomic and quality characteristics were done as follows: a) Heading date: observation in days from the seedling emergency to the plant heading at the moment in which 50% of the plants reach heading. b) Grain Yield: weight of grains of the total plot, done only in the selected lines. The technological quality analysis performed on the selected lines were: a) SDS-Sedimentation, using the Sodium Dodecyl Sulfate (MS-SDS) method (Peña et al, 1990). b) Protein content, the total protein percent was evaluated by the Kjeldahl method.

The statistical analysis of the data was done using the Minitab and Excel 7.0 programs, performing additionally the Tukey Test of the means, following the methodology of Mischan & Pinho (1996) for unbalanced data.

RESULTS AND DISCUSSION

The statistical analysis performed on the C1 to C13 populations comprised by different numbers of selected F₃ lines, aimed in the identification of the higher potential ones for simultaneous selection for grain yield and technological quality. The heading date values indicated that the lines C6, C7, C9 and C13 could be classified as having early maturity cycle. The late cycle of populations C2, C3, and C11 is probably due to the fact that at least one parent of these populations is late maturity (Table 2). The grain yield analysis can be seen in Table 3. The populations C6 and C9 had a better performance for mean and maximum grain yield attained. The variance between and within populations indicates good potential for genetic variability for the trait.

C12, C3, C8 and C1 had better performance among the populations regarding the sedimentation values (Table 4). Good heritability values for SDS sedimentation volume in wheat crosses were found by Matuz (1988). This indicated the possibility of obtention of significant genetic gains.

The populations identified as C2, C3, and C11 showed better performance in terms of protein content (Table 5). This indicated strong relation with technological quality, according to the work done by Wall, (1979) and Preston et al, (1995). Although several populations had shown a good performance considering the technological quality parameters, it should be pointed out that the environmental conditions of cultivation, and grain handling could alter the values which express the quality of the lines.

CONCLUSIONS

Both agronomic characteristics of high grain yield and early heading date, along with information of technological quality performance are important in the development of advanced breeding lines which will potentially produce new cultivars. The data presented in this research work allows the visualization that certain superior populations can combine the desired characteristics of the wheat breeding priorities, helping the farmer and at the same time the miller, the baker and the final consumer to have a better product.

ACKNOWLEDGEMENTS

We are grateful to Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for financial support. The authors are also thankful to the technical support work provided by Valter Geraldo Moretto (AMG) and Maria Isabel Florentino Ferreira (AEF) of IAPAR.

RESUMO

O objetivo do trabalho foi combinar seleção simultânea para produtividade e qualidade tecnológica em populações segregantes elite de trigo, desenvolvidas pelo programa de melhoramento genético do IAPAR. Treze populações foram escolhidas, de acordo com a potencialidade de variabilidade genética na geração F₂. Procedeu-se a seleção de espigas individuais as quais foram semeadas no sistema de espigas por fileira. Na geração F₃ realizou-se a seleção individual de linhas, para potencial produtivo. Características como número de dias para o espigamento e peso de parcela foram determinadas. Sementes das linhas selecionadas, foram avaliadas para qualidade tecnológica por meio da análise de Sedimentação e teor de Proteína. As populações foram denominadas de C₁ a C₁₃, representando os diferentes cruzamentos. O número de linhagens selecionadas dentro de cada população variou de um a doze. As populações C6, C7, C9 e C13 foram classificadas como de maturação precoce. Duas populações (C6 e C9) apresentaram maior potencial de produtividade de grãos. Quatro populações C12, C3, C8 e C1destacaram-se para a média e variância de sedimentação. As populações C2, C3 e C11 destacaram-se para teores médio, máximo e também variância de proteína. Os resultados obtidos indicam condições favoráveis de obter-se linhagens com elevado rendimento de grãos associados com melhor qualidade tecnológica.

Received: October 19, 1999;

Revised: July 31, 2000;

Accepted: August 31, 2000.

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Author for correspondence

Publication Dates

• Publication in this collection
  07 Nov 2001
• Date of issue
  June 2001

History

• Accepted
  31 Aug 2000
• Reviewed
  31 July 2000
• Received
  19 Oct 1999