Barley landraces from the western Mediterranean area have not been thoroughly exploited by modern breeding. This study aims at assessing the agronomic value of a core collection of lines derived from landraces of Spanish origin and to compare them with sets of successful old and modern cultivars. The agronomic performance of a set of 175 barley genotypes, comprising 159 landrace-derived lines and 26 cultivars, was evaluated in a series of 10 field trials, carried out over 3 years and several locations. The most relevant trait of the landraces was higher grain yield at low production sites than cultivars, which may be related with better ability to fill the grain under stressful conditions. On the other hand, lateness, excessive plant height and lodging were negative traits frequently found in the landraces. Large genotype-by-environment interaction (GEI) for grain yield was detected, related partly with differences between germplasm groups, probably indicating local adaptation. GEI was also associated with the interaction of heading time and powdery mildew resistance with temperature. Material and MethodsPlant material: A total of 182 genotypes were evaluated in field trials. The set comprised the following subsets: 145 six-row and 11 two-row This research was carried out at EEAD-CSIC, ITACyL-Valladolid and IRTA/UdL-Lleida. Spanish inbred lines, derived from landraces after at least three generations of head-to-row purification; sixteen old cultivars, widely used in Spain during the 20th century, eight two-row (Alpha, Beka, Hassan, Kym, Pallas, Union, Wisa and Zaida) and eight six-row (Ager, Albacete, Almunia, Barberousse, Dobla, Hatif de Grignon, Monlon and Pan e); and, finally, 10 cultivars, recently bred or currently grown in Spain, used as controls of good agronomic performance (Candela, Orria, Plaisant and Steptoe six-row; Gaelic, Graphic, Nevada, Seira, Tipper and Volga two-row). The first three groups, six-row and two-row landracederived inbred lines and old cultivars, constitute the Spanish Barley Core Collection (SBCC; Igartua et al. 1998).

Seven thousand years of barley cultivation under the environmental hardships typical of the Mediterranean climate have generated genetic singularity of the Spanish barleys, consistently reported in the literature. From the Spanish National Collection of 2289 accessions, a core subset with 159 landraces and 16 old varieties was constituted. Twenty-seven characters were evaluated for the core collection, to define the structure of the diversity. Several evaluation trials were carried out in 1999-2000, whereas yield trials were performed in earlier years. Phenotypic diversity was large for most of the characters studied. Comparisons of genetic diversity between the core and the original collections suggested that the core is a good representation of the existing diversity in the BNG. Comparisons with results of studies on Spanish materials from other collections seem to indicate that the Spanish diversity is not well represented in some world collections. Principal component analyses for quantitative and qualitative characters revealed a clear distinction between two- and six-row cultivars, and also between landraces and commercial varieties. Geographical origins of the landraces were correlated with grain yield, heading date, duration of grain filling period, and growth class. In relation to diseases, altitude played an important role on the resistance to powdery mildew and brown rust. For brown rust, all the resistant landraces came from low altitudes. These geographical gradients seemed consistent with prior knowledge about barley adaptation, and would confirm the agreement between passport data and true adaptive origin of these landraces from a geographical point of view.

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Malt extract yield (EXT) and barley protein content (BPROT) data from 346 EBC trials located across all the EBC countries, and composed of many different varieties, from the years 1980,1982 to 1990, inclusive, and 1993 to 1995, thus covering 13 seasons, were used to detect regional trends affecting the negative correlation between these two variables. Quadratic curves were fitted to data from each European region (North, Central, West and South), all ofwhich showed very high coefficients of determination (r2). A common trend in all regions, and also in the overall European analysis, was of EXT decreasing when BPROT increased, although the extent of decrease varied among the regions. Two different geographical pattents of variation in EXT with changes in BPROT have been observed, on the one hand those of the Iberian Peninsula and West region, and on the other, those of the North and Central regions. In the first case, the rate of decrease in EXT was almost constant across the full range of variation of BPROT, whereas, in the second case, the decrease in EXT grew progressively with increases in BPROT. Tlierefore, although "Bishop's law" on EXT decrease with BPROT increase holds true as a general statement, it would be necessary to take climatic differences into account when estimating EXT values from BPROT data.Key Words: Barlei/, malting quality, protein content. INTRODUCTION subsequent general acceptance of his findingsFollowing the classical work of Bishop in the 1930s'" worldwide. From this general acceptance, it has been barley protein content has been considered to be a always inferred that barleys from southern Europe were detrimental trait for malting quality, as it is negatively of inferior malting quality to those from humid regions, correlated with malt extract yield. It was stated, due to their generally higher protein content. There are, however, that the inverse relationship between extract however, doubts about the general validity of this negative and protein had a varietal, i.e. genetic, component, so correlation in predicting extract values from the protein a different correlation existed for each variety. It is now contents of barleys grown under very contrasting known that this negative correlation is mainly due environmental conditions. The reason is the unknown size to the hordein fraction of the proteins, not only because oi the environmental (E) and genotype x environmental of its negative correlation with starch19, the main (GE) induced variation, source of extract, but also due to its physical role as the major component of the endosperm protein matrix into Genotype x environment interaction is one of the causes which the starch granules are embedded, restricting of the unpredictable variation found in quantitative access by amylolytic enzymes during germination12.characters of cultivated plants (see review in reference 16) such as malting quality traits (see reviews in 7,9).Bishop worked out his equations from data obtained studies on GE of malting quality parameters conducted on barl...