ESTIMATION OF HERITABILITY AND SELECTION GAIN FOR 

 BLISTER RUST RESISTANCE IN WESTERN WHITE PINE 



W. A. Becker and M. A. Marsden 

 Genetics Program, Washington State University , Pullman, Washington, 

 and Intermountain Forest and Range Experiment Station, Forest 

 Service, U.S. Department of Agriculture, Moscow, Idaho, U.S.A. 



.ABSTRACT 



Disease-free western white pines {Finus monticola) were located 

 in northern Idaho and crossed with four tester trees . Seed 

 progenies from crosses were sown in the fall of 1964 at the 

 Intermoimtain Forest and Range Experiment Station's nursery in 

 Moscow, Idaho, and seedlings therefrom were exposed to the 

 blister rust disease pathogen {Cronartium ribicola) in the fall 

 of 1966 during the seedlings' second year of growth. Two years 

 later (fall, 1968) the proportion of healthy seedlings per plot 

 was determined and the plot data adjusted for small numbers and 

 transformed to the arc sine of the square root of the proportion 

 (the derivation of the binomial model and transformation is 

 explained in an appendix) . 



In a factorial analysis of variance estimates of additive 

 genetic and dominance variance were obtained. Dominance 

 variance was high in relation to additive variance. Herita- 

 bilities for selection on an individual basis for three eleva- 

 tion groups were: 5, 3.2%, and 7.0%. Heritabilities for 

 selection by progeny testing candidate trees ranged from 38.6% 

 to 66.0%. The predicted selection gains were: selection of 

 candidate trees in the forest, 11.3 to 23.1%; selection of 

 candidate trees by progeny testing, 3.5 to 8.4%; selection of 

 individual seedlings based upon ability to remain healthy 

 after artificial inoculation, 0.1 to 1.4%. The total gain 

 ranged from 14.9 to 30.5%. 



The heritabilities and selection gains from the last two 

 methods were lower than had been previously reported from 

 this experiment station. Gains for the selection of healthy 

 trees in the forest were greater than previously obtained 

 possibly due to the inoculation of the seedlings during 

 their second growing period than during their first growing 

 year. 



Disease-free mature western white pine {Finus monticola Dougl.) trees 

 located in heavily infected areas (candidates) from three elevations (low ■ 

 below 3,299 feet; mid - 3,300 to 4,099 feet; high - 4,100 feet and above) 

 were crossed with tester trees from their own elevational zone. "In fall, 



397 



