Genetic improvement of the seringueira tree (Hevea spp.) for the state of São Paulo

Abstract

One of the most important characters in the genetic improvement of the cultivated rubber tree is the production of latex, the citoplasmatic fluid extracted continually from the stem of the trees, through successive cuts of thin bark slices, denominated “tapping”. However, the expression of that potential is usually influenced by several inherent genetic factors to the tree, as vigour, bark thickness, resistance to wind, to diseases, etc. and for such environmental factors as: management practices such as tapping system, stimulation, planting density, nutrition, etc. The breeding cycle to obtain planting cultivates adopted by the Instituto and other research institutions, includes three selection stages. Initially, the development of progenies, by poen or controlled pollination, seeking the formation of progeny nurseries. At the age of two and a half years, based in preliminary evaluations of production through early tests, vigour and tolerance to diseases, the cuts are selected and cloned to be tested in Small Scale Clone Evaluation Trials (EAPEs). In this second stage of selection cycle, after the first year of tapping, the promising clones are multiplied and they start to be assessed Large Scale Clone Evaluation Trials (EAGEs). In this last stage it is usually spent from 12 to 15 years, until a clone can be recommend for planting in large scale without risk to the planter. Based on the exposed the project has as main objective the obtainance of superiors cultivate (clones) rubber tree with high yield potential and vigour, resistant the Microcyclus ulei (P. Henn.) v. Arx. for the different areas of the plateau and coast of the State of São Paulo. The project includes 28 trials of the three groups. The first related to study and selection of progenies, the second related to the Evaluation of Clones in Small Scale (EAPEs) and a third party to the Evaluation of Clones in Large Scale (EAGEs) most of them at the Instituto Agronômico de Campinas. All involve the controlled-pollination to the final liberation of clones at planter level. In the evaluation of the experiments, among other tarits, will be considered rubber production, annual evaluations of girth growth, leaf diseases and tapping panel, plant architecture aiming the resistance to wind and quality of the produced rubber. (AU)