Two-Stage Selection in Slash Pine Produces Good Gains in Fusiform Rust Resistance

Abstract

Abstract The best 6 of 21 progeny-tested first-generation slash pine selections were crossed in a half diallel to study inheritance patterns of their superior fusiform rust resistance (5 trees) and height (1 tree). Their six first-test progenies were duplicated and included in the study. These two groups of progenies, along with two commercial check lots, were planted on an Upper Coastal Plain and a Flatwoods site in Georgia. At age 10 yr, the 15 progenies in the half diallel averaged 23% rust-infected compared with 54% for the check lots. First-test progenies averaged 30% infected. For percentage infection, the six parents differed in general combining ability (GCA) (0.01 > P > 0.001) on both test sites and in specific combining ability (0.05 > P > 0.01) on one site. GCA variation for height was significant (0.05 > P > 0.01) on one site. The parent selected for height had the highest breeding value for height at age 10 yr. These results show that resistance to the fusiform rust disease, a serious problem in management of the species, can be improved in slash pine. These 6 parents and their 15 progenies in the half-diallel cross are a good source of rust resistance genes for use in slash pine improvement programs. South. J. Appl. For. 20(3):143-147.