GRAIN YIELD AND MORPHO-PHYSIOLOGICAL CHANGES FROM 60 YEARS OF GENETIC IMPROVEMENT OF WHEAT IN IRAN

Abstract

SUMMARYIn order to understanding the changes in morpho-physiological traits of wheat cultivars released from 1940 to 2000 in Iran and to determine the association of these traits with grain yield, an experiment was conducted with 15 wheat cultivars released over the past 60 years using an randomized complete block design with four replications. The experiment was conducted on an experimental farm of Arsanjan Islamic Azad University in 2005/6 and 2006/7. Results indicated that cultivar grain yield was significantly correlated with year of release over the 60 years (r= 0.878,p< 0.01). Harvest index and biological yield increased significantly with increasing grain yield. The change in the photosynthesis rate was not significant during this period but transpiration rate and stomatal conductance and chlorophyll index increased significantly. Among yield components, grain number per ear increased significantly but increase in ear number was not significant. Plant height decreased significantly in new cultivars. In conclusion the results showed that wheat yield improvement in Iran is associated with increasing harvest index, grain number per ear, transpiration rate, stomatal conductance and decreasing plant height.