Performance of rubber tree crown clones resistant to South American leaf blight

Abstract

^{The objective of this study was to evaluate the performance of 18 rubber tree clones, resistant to Microcyclus ulei and used as budded crowns. Eight hybrid clones of Hevea pauciflora x Hevea guianensis var. marginata, eight of H. pauciflora x H. rigidifolia, and two clones of H. pauciflora were used as budded crowns onto CNS AM 7905 – a primary selection of H. brasiliensis – and cultivated in a Xanthic Ferralsol, in Manaus, Amazônia, Brazil. Trunk girth, nutritional status and rubber productivity were evaluated. The budded crowns of hybrids of H. pauciflora x H. guianensis var. marginata cause fastest trunk girth increment, with shortening of the imaturity period of rubber tree. The high resistance level of H. rigidifolia hybrids to Leptopharsa heveae justifies the introduction of other genotypes of this species, for new hybridizations. The clones CPAA C 01, 06, 13, 15, 16 and 45 present excellent potential for dry rubber production, in the climatic and upland soil conditions of Tropical Amazônia.}