Effectiveness of the visual symptom score in selecting germplasm for resistance to the barley yellow dwarf virus disease in wheat (Triticum aestivum L.)

Abstract

The effectiveness of the visual symptom score in selecting germplasm for resistance to barley yellow dwarf (BYD) was studied using 33 F5 wheat (Triticum aestivum L.) lines from crosses between tolerant x tolerant and tolerant x susceptible parents (experiment 1) , and 28 advanced lines (experiment 2) . In both cases the material had been selected on the basis of low visual symptom scores for 2 to 5 years. Replicated paired Hill-plots were stablished in the field at Davis, California. One of the paired plots of each genotype was sprayed with insecticide to reduce the aphid population. Each hill-plot was scored for BYD symptom expression using a visual 0 to 9 scale. Data were collected for plant height, biomass weight, grain yield, spike number/hill-plot, number of kernels/hillplot, number of kernels/spike, and 2 00-kernel weight were collected in both experiments to examine the relationships with the BYD symptom score.