Goals of this work were to evaluate genetic variability and potential of successful simultaneous selection for short stature and high rubber yield, considering relational variables: rubber yield per height unit (PBA) and rubber yield per plant basal area (PBB), both as new traits in rubber tree genetic improvement. Selection based on these variables allows identification of new genetic material suitable for high density plantations. Twenty-two half-sib progenies of half-sibs were established in Votuporanga. The trial was carried out with 22 treatments with five replications each and 10 plants per plot, planted in single lines at density of 3 x 2m. Plots were randomly distributed. At three year old age, progenies were evaluated and showed that a combination of those two traits increased genetic variability available for selection. Results also demonstrated that it is possible to have an efficient genetic improvement for simultaneously increasing rubber yield while reducing plant height. Therefore, it is possible to improve these two traits (PB and PBB) simultaneously, without losses on the main traits (PB). High correlations between PBB and PBA (0.842) and between PBB and height (-0.578) show that selection based on PBB will lead to height reduction. The type of selection proved itself efficient for increasing rubber yield while substantially reducing plant height and less reducing trunk perimeter. All these effects are desirable in a rubber tree genetic improvement program aiming at selection of genotypes suitable for higher density plantations.
Hevea brasiliensis; genetic improvement; rubber yield; short plant height
