DIALLEL ANALYSIS OF THE LATENT PERIOD OF STRIPE RUST IN WHEAT

A half diallel was made amongst five wheat (Triticum aestivum L.) geno types of which one was susceptible, while the others had adult-plant r esistance, to stripe rust (Puccinia striiformis West.). The five paren t and ten F-1 progeny were grown in the glasshouse and were inoculated with three rust pathotypes at the seedling stage. The latent period w as measured on the first leaf. Two procedures were used to analyze the half diallel. Both methods showed that the average effects of alleles were of much greater importance than was dominance in conditioning re sistance in response to two of the pathotypes, while for the third pat hotype dominance was important. Resistance was conditioned by partial dominance for two pathotypes whereas for the third it was determined b y full dominance. Broad-sense heritabilities range from 60-73% and the number of genes involved was different (from 1 to 4), depending on th e pathotype.