Evaluation of morphological characteristics related to lodging in selected local and improved rice (Oryza sativa L.) genotypes

To evaluate the morphological characteristics and lodging related traits in local and improved rice genotypes, a field experiment was carried out using randomized complete block design with three replications in 2013 at the Rice Research Institute of Iran, Rasht, Iran. Rice genotypes included three local cultivars (Hashemi, Sangjo and Alikazemi) and three improved lines (841, 831 and 416). Results showed significant relationship between average diameter of internode whit breaking resistance of third internode (r = 0.961**) and average diameter of fourth internode whit breaking resistance of fourth internode (r = 0.902**), average diameter of third and fourth internode with pushing resistance (r = 0.884** and r = 0.853**, respectively). Also significant positive correlation between fresh weight:length ratio of internode whit breaking resistance in third internode (r = 0.937**) and pushing resistance (r = 0.752*), fresh weight:length ration of internode with breaking resistance in fourth internode (r = 0.825**) and pushing resistance (r = 0.810**) were observed. Stepwise regression analysis showed that average diameter of internode was the only trait that significantly affected the pushing resistance, and explained 88% of observed variance alone. Fresh weight:length ratio of internode had highly significant effect on breaking resistance (r2 = 0.86) which corresponded with the results of correlation analysis. It seems that the thickness and weight:length ratio of internode have major roles in resistance of rice plant to lodging and could be considered as indirect criteria in selection for resistant to lodging in rice breeding programs.