Evaluation of morphological characteristics related to lodging in native and improved rice (Oryza sativa L.) cultivars

Plant lodging is one of the major problems that may occur depending on the time to 50 reduction in yield of rice crop. Identification of plant characteristics related to lodging resistance considered as the prerequisite for reduction of losses in rice cultivation. In order to evaluate the morphological characteristics and lodging related traits in native and improved rice cultivars, a field experiment was laid out in randomized complete block design with three replications in 2012 at the Rice Research Institute of Iran, Rasht. Rice genotypes including three native rice cultivars (Hashemi, Sangjo and Alikazemi) and three improved (Kadous, Gohar and Khazar). Results showed correlation between thickness of internode whit breaking resistance of third internode (r=0.914**) and thickness of fourth internode whit breaking resistance of fourth internode (r=0.846**), thickness of third and fourth internode whit pushing resistance (r= 0.935** and r= 0.926**, respectively). Also significant positive correlation between fresh weight/length of internode whit breaking resistance in third internode (r= 0.967**) and pushing resistance (r= 0.870**), fresh weight/length of internode whit breaking resistance in fourth internode (r= 0.922**) and pushing resistance (r= 0.835**) were observed. Stepwise regression analysis showed that thickness of internode was the lone trait that significantly affected the pushing resistance. fresh weight/length of internode and dry weight/length of internode had highly significant effect on breaking resistance that was in correspondence with the results of correlation analysis. It seems that the thickness and weight/length of internode, have major roles in rice plant resistance to lodging and could be considered as indirect indices in selection for higher resistant rice cultivars.