Estimation of genetic data and breeding values of traits related to wax production in Rhus succedaneaL. clones using the REML/BLUP method

AbstractRhus succedaneaL. is cultivated in Japan for the wax that can be extracted from its fruits. We determined genetic data for specific traits associated with wax production (fruit number per cluster, FN, fruit weight, FW, number of clusters per area, CN, and wax content, WC) in five traditional cultivars and 13 newer clones. Data were collected over 4 years and alternate bearing was observed: 2001 and 2003 were years with high yields; in 2002 and 2004 yields were poor. The restricted maximum likelihood method was used to calculate (co)variance components for analysis. Broad sense heritability was estimated and ranged from low (FN and CN) to high (FW and WC) for the traits examined. There were positive genetic correlations between FW and WC and negative ones between FN and FW throughout the 4 years. Genetic correlations between CN and the other traits were positive in good crop years and negative in bad crop years. For each assessed clone, the four traits in the 4 years were evaluated using best linear unbiased predictors (BLUP) of the clonal breeding values. The BLUP scores for both FW and WC exhibited positive correlations between pairs of years, whereas there were positive BLUP correlations for CN when the high yield and low yield years were examined separately. The traditional cultivars and the newer clones were also characterized. Some of the clones were better than the traditional cultivars with regard to wax yield and reliability of production. The trait characteristics and the future breeding are discussed.