Source Year: 1996

The variability and repeatability of characteristics of the laticiferous system of the bark of 76 3-year-old plants of rubber (Hevea) were studied in Sao Paulo, Brazil. Observations were made on bark thickness (BT), total number of latex vessel rings (NLVR), diameter of latex vessel rings (DIA), density of latex vessel rings per 5 mm per ring averaged over all rings (DD), and average distance between consecutive latex vessel rings (DLVR). Based on the analysis of variance, coefficients of repeatability and genetic gains were estimated for each charecteristic for 2, 3,4 and 5 different height samples taken from the stem of each seedling. The heighest average repeatability values were observed for DLVR and BT, respectively. These highest genetic advances were obtained for BT and NLVR with 4 and 5 samples, respectively. The repetability and genetic gain obtained with 3 bark samples were only slightly less than with 4 and 5 samples, and gave a better progress in the selection.