Relationships between yield and some structural traits of the laticiferous system in Hevea clones resistant to South American leaf blight
Dominique Garcia; Vincent Le Guen; Carlos Raimundo Reis Mattos; Paulo de Souza Gonçalves and André Clément-Demange
Latex yield and six anatomical bark traits were measured in a five-year-old rubber tree clonal trial planted in Ituberá (Bahia, Brazil), on forty-nine different clones. The clones were pre-selected for resistance to SALB (South American Leaf Blight) caused by the fungus Microcyclus ulei (P.Henn.) v. Arx. The studied traits were : average yield (AY), girth (SC), virgen bark thickness (BT), total number of latex vessel rings (NR), average density of latex vessel per ring (DV), average diameter of latex vessels (DL) and average distance between consecutive latex vessel rings (AD). Phenotypic, genotypic and environmental correlations, and coefficient of genetic prediction (CGP) were calculated for all characters. There were considerable genetic variations between clones for AY, NR and BT, as indicated by high values of CGP. The genetic correlations were significant between AY and NR. The possibility to use NR as predictor of AY is discussed and the expected gains in percent of several references for AY are computed. FDR 4575, FDR 6099, FDR 5240, FDR 2010, FDR5597, CDC308, FDR 4151, CDC 943, MDX 608 clones were retained for their potential yield and recommended for multilocation large scale trials.