1Cámara Arbitral de Cereales de Bahía Blanca, Saavedra 636, 8000 Bahía Blanca, Argentina; ²CIC (CERZOS-Dpto. Agronomía, UNS); ³Dpto Agronomía UNS; laboratorio@cacbb.com.ar

Keywords: quality – estability - genotypes

Wheat is grown in a wide range of environments that affect overall performance, particularly grain yield and end-use quality. Wheat yield and end-use quality depend upon the environment, genotype, and their interaction. The milling industry requires to store the different wheat types separately on the basis of their end-use properties and to blend properly the grain to obtain the optimal flour for the particular processing of interest. It is therefore clear that the classification of the different lots of wheat is a crucial matter. During the later two decades, the wheat yields in Argentina were increasing and its quality parameters were decreasing. The main quality characteristics for the wheat utilization are flour extraction (milling yield), flour protein concentration, dough handling characteristics rheological properties. These characteristics usually are influenced by cultivar and interactions of cultivar and environment (Peterson et al., 1998; Eskridge et al., 1994). This influence is depending on varietals differences, cultivation practices and environmental effects, which in turn reflect the interregional and year-to-year differences and the climatic conditions. However, magnitudes of the interaction effects often are small compared with cultivar main effects. The objective of this work was to evaluate the main wheat characteristics to select the more important for bread making quality evaluation. The development of classification models of general validity requires the use of a set of samples representative of the existing variability, i.e., heterogeneous for genotype, environment and year of harvesting. The objectives were to evaluate the influence of genotype different on wheat quality and the relationship between different parameters.

For this reason, from the total commercial samples analyzed in the Cámara Arbitral de Cereales of Bahía Blanca during the period 2002-2005 were selected 573 commercial wheat samples coming from compound groups for individual partings belonging to 3 different genotypes groups which they were collected during 3 consecutive years (2002 to 2004) from 54 Departments (Buenos Aires and La Pampa Provinces). The wheat samples were grouped in three categories based on genotype differences (visually and A-PAGE) and their industrial bread making quality: Quality Group 1 (QG1), Quality Group 2 (QG2) and Quality Group 3 (QG3), according to "Winter Cereals Committee of Seed National Commission (CONASE)" classification. Grains were analyzed for protein (Prot), gluten and thousand kernel weight. They have been milled (with a laboratory mill) to obtain the alveographic indexes and the farinograph stability.

High correlation was observed between grain protein and gluten every study year and taking into consideration all samples (P<0.001; R²=0.85).

During the three study years, the W value was associated to grain protein (P<0.001; R²=0.55) and gluten content (P<0.001; R²=0.51). The relationship between W value and protein content was significantly improved when genotype differences were taking into consideration (Figure 1). The final relationship between these variables was:

W = - 68.8 - 60.6 Group + 43.1 Protein

(R² = 0.83; P<0.001; n = 545)

These results showed the some environment/management characteristics, through protein content, and Quality Group can explaining around of the 83% of the variability found in W values.

Genotypes from QG2 and QG3 could reach adequate quality when its protein content is enough high.

Grain protein and genotype may be the best predictors of the suitability for the alternative end-use possibilities. These two parameters could be very useful tools to improved wheat commercialization.

Because of there was interaction between genotypes/environment, we analyse each year separately. A quality stability analysis in the whole region (54 departments) using as dependent variable W demonstrated that there was difference among three QG (1-2-3). QG1 were W values higher than QG 2 and QG 3. It can be visualized by origin ordinate and slope of each one of the straight lines. It is necessary highlight that GC1 wheat had the biggest answer to optimum environments, being QG3 wheat indifferent to the environment; they had W values low and low stability in all harvest. The QG2 wheat had an intermediate behaviour and near to QG1. These results were for three harvest (2002 – 2003- 2004). (Figures 2, 3 and 4).

Peterson, C.J.; Graybosch, R.A.; Shelton, D.R. and Baenziger, P.S. 1998. Baking quality of hard red winter wheat: Response of genotypes to environment in the Great Plains. Euphytica 100:157–162

Eskridge, K.M.; Peterson, C.J. and Grombachei, A.W. 1994. Probability of wheat quality traits falling within acceptable limits. Crop Sci. 34:866–869.

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