Evaluation of trend changes in grain yield and physiological characteristics in 15 varieties spring bread wheat.

This study has been done for Evaluation of trend changes in grain yield and characteristics physiological in 15 different bread wheat which have been produced between 1930 -2008. It has been done block random and three times repeat on the farm in research cultivating and sowing institution in 2010 2011. Average analyze of squares showed that there are some clear differenced between Genotypes for major of studied items and specification and in statistics. Checking the changing processions in the meantime shows that the action of harvest index, Biologycal yield, Plant height, Weight of 1000 grains, Number of grain in spike, Number of grain in m2, Days to heading, Days to anthesis, Days to physiological, its weight has accelerated during time. 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.