Yield increase in crops has occurred due to plant breeding and improved production and management techniques. The amount of increase due to plant breeding in soybean in the southern USA has not been determined. The objective of this study was to evaluate the genetic improvements in soybean yield and other important agronomic traits. ‘CNS’ and ‘S‐100’ were chosen as representative ancestral lines from the 1940s. ‘Ogden’ and ‘Lee’, ‘Hill’ and ‘Essex’, and ‘TN 5‐85’, and ‘Hutcheson’ were released in early 1950s, late 1950s and early 1970s, and late 1980s, respectively. The experiments were conducted in Knoxville Experiment Station in Knoxville, TN and at the Ames Plantation near Grand Junction, TN, for 3 yr, and at the Milan Experiment Station in Milan, TN, and at the Highland Rim Station in Springfield, TN, for 2 yr. Results showed that cultivar improvement increased soybean yield 14 kg ha−1 per year. Yield increase over time was linear. This linear increase demonstrates that a yield plateau in the U.S. Midsouth has not been reached in soybean [Glycine max (L.) Merr.]. Most of the increase has come via genetically related elite by elite parent crosses. However, infusion of exotic germplasm into elite germplasm can often promote increases in yield, as in the development of Hutcheson. Current cultivars showed better yield stability and more response to favorable growing conditions than ancestral lines. Genetic improvement resulted in shorter plant height and decreased lodging. Oil content was increased until the 1980s, but then started to decrease. However, because of correlated effects, protein content started to increase after the 1980s.

The objectives of this study were to evaluate dry matter (DM) yield and seed yield of six leafed and semi-leafless pea (Pisum sativum L.) genotypes, and to compare them for these traits. Evaluation of genotype × environment (G × E) interaction, stability and cluster analysis were also carried out at eight diverse locations with typical Mediterranean and Mediterranean-type climate during the 2001-2002 and 2002-2003 growing seasons. Significant differences were found among the pea genotypes for DM and seed yield on individual years and combined over years, and in all locations. All interactions which related to G × E interaction showed significance (P>0.001) for DM and seed yield. The highest yield (4789 kg ha -1 ) was obtained from the leafed genotype 'Urunlu'. However, stability analysis indicated that for DM yield, the leafed genotypes 'Golyazi' and 'Urunlu' should be grown in low yielding and high yielding environments, respectively. Cluster analysis, based on grouping locations, showed that P101 was the preferred variety in low yielding environments, and P98, in high yielding ones. It was suggested that the use of both stability and cluster analyses might give better results. Comparison of cluster and stability analyses showed that the stability analysis fails to recommend cultivars to different regions where yield potential showed significant differences. It seems, however, that cluster analysis could be a powerful tool to examine G × E interaction. If the number of environments was sufficient, a separate stability analysis could be run in each cluster.Additional key words: adaptation, cluster, leafed and semi-leafless peas, Mediterranean conditions, stability. ResumenInteracción genotipo × ambiente y análisis de estabilidad para rendimiento de materia seca y de semilla en guisante (Pisum sativum L.)Los objetivos de este estudio fueron evaluar y comparar el rendimiento de materia seca (DM) y de semilla de seis genotipos de guisante con hojas convencionales y semiafilas. Además, se evaluó la interacción genotipo × ambiente (G × E) y se realizaron análisis de estabilidad y tipo cluster en ocho localidades de clima mediterráneo, durante las temporadas 2001-2002 y 2002-2003. Se encontraron diferencias significativas entre genotipos para rendimiento de DM y de semilla, tanto para años individuales como combinados, así como en todas las localidades. Todas las interacciones G × E fueron Field pea adaptation and stability 97 significativas (P>0,001) para rendimiento en DM y semilla. Se obtuvo la producción más alta (4789 kg ha -1 ) con el genotipo de hoja convencional 'Urunlu'. El análisis de estabilidad indicó que, para rendimiento en DM, los genotipos 'Golyazi' y 'Urunlu' deben cultivarse en ambientes de baja y alta producción, respectivamente. El análisis cluster, basado en agrupamiento de localidades, mostró que la variedad P101 fue la mejor en ambientes de baja producción, y la P98 en los de alta producción. Al comparar los análisis de estabilidad y de tipo cluster se vio que el primero falla al recome...

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This study was carried out to determine the extend of changes in erucic acid concentration of rapeseeds which were grown in Carsamba and Bafra Plains of Central Blacksea Region. In addition to field experiments, the same experiment was conducted in the greenhouse to avoid polen transfer from other sources. The first material used was 00 type rapeseed cultivars. In order to ensure a good result, the experiment sites were selected based on the intensity of other Brassica species (B. oleracea, B. rapa, B. nigra). The harvested rape seeds was the seed material of following year. Erucic acid content was measured for seeds obtained each year. The erucic acid content for three genarations showed that it was much lower than the limits for health (0.04 %)