Preliminary assessment of some new rubber tree clones in Manaus (AM)

Abstract

Twenty-five rubber tree (Hevea spp.) clones in two different immature stages were evaluated for their performance, by utilizing ten biometrical characters: yield, by the "yield minitest" (Mendes test); plant height; stem diameter; leaf whorls number; leaf whorls length; leaf thickness; total number of latex vessels rings; latex vessels diameter; density of latex vessels per 5 mm per ring; and average distance between consecutive latex vessels rings. The treatments were composed of primary clones (originated from a wild rubber tree selection), polyploids, and primary and second hybrids. The polyploid clones IAC 207 and IAC 222 showed the best performance concerned to yield. A poor adaptability to the ecological conditions of Manaus was observed for the primary clones from Acre and Rondônia, except for AC 53. In general, good vigor performance was observed in the clones IAN 6158, Fx 4037, AC 53 and IAN 717. However, great alterations in the vegetative development of the clones appeared in the second year in comparison to the first year: this means that the evolution must take place during a greater number of years. Largo effect of clones x year interaction on the yield, bark thickness, total number of latex vessels rings and density of latex vessels rings per 5 mm per ring was observed. A dose relationship between bark thickness and yields was also observed.