Evaluation of trend changes in grain yield and characteristics physiology in 15 varietie facultative and winter bread wheat.

ABSTRACT To estimate genetic progress and the variation in grain yield and characteristics physiology in facultative and winter bread wheat in 15 wheat (Triticumaestivum L.) cultivars with facultative and winter growth habit released in Iran between the 1930 and 2010, a field experiment was conducted using randomized complete block design with three replications at the Seed and Plant Improvement Institute’s Research Field Station in Karaj, during the 2010-2011 crop cycle. Results of analyzing average square of characteristics indicates significance difference between genotypes for most characteristics at statistical probability level of 1% and there is great diversity between genotypes with respect to these characteristics. Trend of temporal variation in the traits measured revealed that yield components, harvest index and biological yield have increased in more recent released cultivars, however, Physiological attributes including crop growth rate increased in recent varieties in comparison with the older cultivars but the similar trend was not found for relative crop rate in recent varieties.