Genetic improvement of agronomic and quality traits of wheat cultivars introduced to temperate regions of Iran during 1942 - 2007

Wheat is an important food crop to mankind. In order to assess the effects of plant breeding on yield and other characteristics of wheat cultivars released by Iran Seed and Plant Improvement Institute during the period of 1942 to 2007, 21 spring wheat cultivars recommended for temperate regions were evaluated for two successive years for yield, agronomic traits and quality attributes . Results showed that plant breeding has increased the grain yield through the decrease of plant height and the increase of harvest index. Number of grains per spike was higher in modern varieties than older ones. Contrary to grain yield and its components, protein content and majority of other quality parameters either did not change or decreased significantly during the same period. Evidence supported the hypothesis that breeding efforts have led to reduction in baking quality of Iranian wheat cultivars. Cluster analysis divided the cultivars into three main groups of old, medium and modern varieties. Factor analysis showed that quality parameters and phenological traits, while not following time-trends, accounted for most of the variations among the cultivars.