Evaluation and inheritance of resistance to Russian wheat aphid in barley

Russian wheat aphid (RWA): Diuraphis noxia is a serious pest of cereals in various regions of the world. Seventy-six barley genotypes collected from different areas in Iran were subjected to an initial mass screening test and six susceptible and 17 apparently resistant genotypes were identified. To determine resistance mechanisms, antixenosis, antibiosis and tolerance tests were conducted and selected genotypes were ranked according to their plant resistance indices. Four crosses were made between the two most resistant lines (Shz.B-106, and Shz.B-108) and two most susceptible lines (Shz.B-105 and Shz.B-107). F-1, F-2 and BCF1 (backcross to the resistant parent) seedlings were screened for RWA resistance in the greenhouse by artificial infection. Resistance in Shz.B-106 was apparently controlled by a semi-dominant gene, whereas resistance in Shz.B-108 was controlled by a dominant one.