Obtaining superior genotypes of rubber trees (Hevea spp.) for the state of São Paulo

Abstract

The most important character in the genetic improvement of rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss) Muell.-Arg.] is the production of latex. However, the expression of this potential is usually influenced by several genetic factors inherent to the tree, such as vitou as force, bark thickness, wind resistance, diseases resitance, etc. and by environmental factors such as management practices, tapping system, chemical stimulation, planting density, nutrition, etc. The breeding program adopted by the Agronomic Institute (IAC), comprises three stages of selection. Initially, the aim is to obtain progeny, via controlled or open-pollinated, Pollowed by the intalation of the pogenies tests. Two and a half years based on preliminary assessments of yield through early, vigour and disease tolerance tests, the ortetes are selected and cloned to be tested in Experiments Evaluation of Clones Small Scale (EAPEs). In this second phase of selection, after the first year of sangria, the promising clones are multiplied and will now be evaluated in experiments at the Large Scale Assessment (EAGEs). Based on the above the project's main objective is to obtain cultivars (clones) superior with high yield potential and force resistant to South American Leaf Blight (SALB), caused by the fungus Microcyclus ulei (P. Henn.) v. Arx. for different regions upland and littoral of São Paulo. The project comprises 13 experiments covering three distinct groups. The first is related to study and selection of progenies, the second assessment of Small Scale Clones (EAPEs) and a third one in the evaluation of Large Scale Clones (EAGEs), most in progress at the Agronomic Institute (IAC). All of them involve from controlled pollination until the final release of the cultivars (clones). In the evaluation experiments, among others will be considered rubber yield, vigor and deseases of leaf tapping panel, canopy shape overlooking the wind resistance and quality of rubber produced. (AU)