The effect of resistance components on reducing yield and its related characters in wheat as infected by Diuraphis noxia (Hemiptera: Aphididae)

Fourteen hexaploid and tetraploid wheat genotypes mostly resistant to Russian wheat aphid (RWA) were subjected to antixenosis, antibiosis, and tolerance tests. Genotypes were then planted in two completely random designs. Seedlings were infested with RWA in one experiment and the other experiment was used as control. Plant height, spike length, grains per spike, 1000 kernel weight, total biomass, and grain yield were assessed in each experiment. The regression of reduction ratio of each character on resistant components was obtained. The relationships between reduction ratios of plant height, grains per spike and total biomass and antibiosis were not significant. Leaf chlorosis was not consistently correlated with plant resistance index and plant tolerance did not show significant relationship with reduction in total biomass.