Estimates of genetic parameters in rubber tree (Hevea spp.). I. General combining ability in juvenile seedlings. In: Agrotrópica v. 11 p. 163-168, 1999.

Abstract

General combining ability estimates (GCA) were obtained for some yield components, plant vigor and disease resistance for an unbalanced mating design involving 15 parents (clones) representing the following populations: Hevea brasiliensis, H. pauciflora and H. benthamiana. The highest GCA values were observed for the clones Fx 3864, AVROS 1126, AVROS 255 and Fx 2261 for the characters dry rubber production. Among these clones, AVROS 1126 and AVROS 255, also presented high GCAs for trunk girth and bark thickness; and Fx 3864 and Fx 2261, small GCAs (low disease) for South American leaf blight severity. These traits seem to be under the genetic control of both additive and non-additive genes. These GCA estimates were greatly affected by the array of parents in the diallel, but not by the fact of considering the use of one or three cycles (10 tappings/cycle) of the modified Hamaker-Morris-Mann test.