Quantitative Genetics of Traits Indicative of Biomass Production and Heterosis in 34 Full-sib F sub(1) Salix eriocephala Families

This project examined the heritability of traits that affect biomass production of Salix eriocephala, a shrub willow native to North America and an essential species in the breeding of bioenergy crop varieties. Using an incomplete factorial design, seven females and eight males were crossed to produce 34 full-sib F sub(1) families. Five to 12 entries per family were planted in four-plant plots in a randomized complete block design on two sites. Melampsora rust incidence was scored in the fall of the first growing season (prior to coppice). Height of the tallest stem, cross-sectional stem area per stool, and number of stems per stool were recorded in the winter after the first growing season post-coppice. Plants were harvested 3years post-coppice and biomass yield was determined. A large percentage of the total variance was additive for all of the traits studied and heritability estimates were low to moderate, suggesting that phenotypic expression of these traits is predictable and can be improved through breeding. Based on yield 3years after coppice, 29 of the 34 families displayed midparent heterosis, ranging from 1-115%, for the composite trait-biomass yield, strongly indicating that offspring often perform better than their parents in this population. This study will assist in selecting parents which may produce superior progeny in the breeding program.