A. Arzani - Agronomy and Plant Breeding Department, College of Agriculture, Isfahan University of Technology, Isfahan, ۸۴۱۵۵, Islamic Republic of Iran.
N. L. V. Lapitan - Soil and Crop Sciences Department, Colorado State University, Fort Collins, CO ۸۰۵۲۳, U.S.A.

The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), is a significant insect pest of wheat worldwide. The objective of this study was to assess the genetic variation within and between F۲-derived families for reaction to RWA using F۳ and F۴ families originating from individual F۲ plants of a cross between the susceptible line (synthetic hexaploid-۱۱) and the resistance cultivar (‘Halt’). The RWA damage of individual plants within each family was measured using different procedures. Their reaction types were combined into a single data for each individual family (derived from an individual F۲ plants) and subjected to statistical analysis. Results indicated that the genetic variation between F۲-derived families is greater than within F۲-derived families for RWA resis-tance. Broad-sense heritability of RWA resistance, calculated by partitioning phenotypic variation into genetic and environmental components, was ۷۳.۲%. A narrow-sense herita-bility estimate of ۳۰% was obtained for the RWA resistance in the ‘Halt’ synthetic hexaploid-۱۱ cross using parent-offspring (F۳: F۴) regression procedure.

Wheat, Genetic variation, heritability, Insect resistance, Russian wheat aphid