Polyploidy in rubber tree: III - comparative study among diploid and the new putative polyploids clones under the conditions of clonal garden

摘要

Rubber production and vigour of the plants were measured in putative clones of Hevea brasiliensis (Fx 3864 pl and Fx 985 pl). The first evaluation of production occurred in the juvenile phase (30 months of field age) by using the HMM-modified test. Asuperiority of the polyploid clones in relation to the diploids was observed for all the appraised characteristics. In the second evaluation, the polyploids did not keep the superiority observed in the first evaluation, presenting similar performance asthe diploid clones. These results, associated to those of cytogenetics analysis, give evidence of the difficulty in obtaining stable poliployds in rubber trees, independently of the polyploidization technique utilised. There is, still, indications of mixoploidy occurrence followed by a probable reversion of the diploid condition, fact this that can be attributed to the speed of multiplication of the cells in the tissues with smaller level of ploidy.