Rubber tree cultivation [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell.-Arg.] uses mostly the budding propagation method, however the expected stand uniformity due to the use of vegetative propagation is theoretical, since high variation for yield and vigor is caused by rootstock influence. The objective of this study was to assess several combinations between clonal rootstocks and clone scions through diallel analysis, aiming at high productivity and vigor. Data consisted of five years of dry rubber yield and girth at panel opening from an experiment using a split-plot design with four replications, conducted at Pindorama, SP, Brazil, considering six rootstocks (GT 1, IAN 873, PB 235, RRIM 600, RRIM 701 and unselected seedlings) and six scions (GT 1, IAN 873, PB 235, PR 107, RRIM 600 and RRIM 701). A 6 × 6 partial diallel analysis summing up 36 combinations was undertaken, and general compatibility for each group of materials (rootstocks and scions) and specific compatibility among all combinations were estimated. The results have shown that PB 235 and IAN 873 rootstocks provided high yields and general compatibility values (7.9348 and 2.7647, respectively). The use of unselected seedlings as rootstocks is not recommended because they presented very low compatibility values for dry rubber yield. Towards growth vigor, the tested rootstocks have shown similar performance. Key words: compatibility, diallel analysis, girth, grafting, rubber tree INTERAÇÃO PORTA-ENXERTO X ENXERTO SOBRE VIGOR E PRODUÇÃO DE BORRACHA DE Hevea brasiliensisRESUMO: Na cultura da seringueira [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell.-Arg.], o método de propagação mais usado é a enxertia, mas a uniformidade esperada usando propagação vegetativa é teórica, uma vez que altas variações para produção e vigor são causados pela influência do porta-enxerto. O objetivo do presente trabalho foi avaliar várias combinações entre porta-enxertos clonais e enxertos (clones) através de análise dialélica, visando-se alta produção e vigor. Os resultados constaram de cinco anos de produção de borracha seca e perímetro de caule na abertura do painel de um experimento em parcelas subdivididas com quatro repetições, conduzido em Pindorama, SP, Brasil, considerando-se seis porta-enxertos (GT 1, IAN 873, PB 235, RRIM 600, RRIM 701 e sementes não-selecionadas -UnS) e seis enxertos (GT 1, IAN 873, PB 235, PR 107, RRIM 600 e RRIM 701). Foi realizada a análise do dialelo parcial 6 × 6, somando 36 combinações, e Compatibilidade Geral (GC) para cada grupo de materiais (porta-enxertos e enxertos) e Compatibilidade Específica (SC) dentre todas as combinações foram estimadas. Os resultados mostararam que os porta-enxertos têm forte efeito sobre a produção de borracha seca, e levaram à recomendação do PB 235 e do IAN 873 como escolhas seguras de porta-enxertos para as condições do Planalto Paulista, sendo que proporcionaram altas produções e altos valores de Compatibilidade Geral (7.9348 e 2.7647, respectivamente). O uso de sementes não-selecionada...

Six laticiferous system characters were investigated in 22 three-year-old, half-sib rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell.-Arg.] progenies, evaluated at three sites (Votuporanga, Pindorama and Jaú, all in the São Paulo State, Brazil). The traits examined were: average rubber yield (Pp), average bark thickness (Bt), number of latex vessel rings (Lv), average distance between consecutive latex vessel rings (Dc), density of latex vessels per 5 mm per ring averaged over all rings (Dd) and the diameter of the latex vessels (Di). The joint analysis showed that site effect and progeny x sites interaction were significant for all traits, except Lv. Estimates of individual heritabilities across the three sites were high for Bt; moderate for Lv, Pp and Dc; low for Dd and very low for Di. Genetic correlations in the joint analysis showed high positive correlations between Pp and the other traits. Selecting the best five progenies would result in genetic gains of 24.91% for Pp while selecting best two plants within a progeny would result in a Pp genetic gain of 30.98%.

In a field trial involving 68 rubber tree (Hevea spp.) clones calculation of genotypic correlation coefficients revealed significant age-age correlation from age 1 to 6 (immature period) for girth A and for age 7 to 12 (mature period) for girth B and for age 7 to 12 (production of latex) for yield. Rank correlation coefficients between all immature ages of girth (girth A), all ages of mature girth (girth B) and all annual rubber production (yield) were significant for the three traits, with the coefficients decreasing with increasing age. Selection of the sets of best 30, 15, 10 and 5 clones from the available 68 clones at a given age was generally accompanied by a descending order of percentage success. It was suggested: (a) to have the best 30 clones of age 6, select the set of best 36 clones at age 2, (b) to have the best 15 clones of age 6, select the set of best 20 clones at age 3, (c) to have the best 5 clones of age 6, select the set of best 8 clones at age 4, and (d) to have the best 3 clones of age 6, select the set of best 3 clones at age 5. More than 80% of the targeted clones on girth A or girth B basis and more than 76.7% clones on yield basis were found to get selected at steps (a) through (d). For achieving early multiplication of the most productive clone for deployment, multiplication should be started with the best 36 (i.e. 60%) clones selected at age 2.

RESUMONa cultura da seringueira [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell.-Arg.] o método de propagação mais utilizado é a enxertia. No entanto, observa-se que a uniformidade esperada pela propagação vegetativa não é verificada em condições de campo, pois altas variações para as variáveis vigor e produção de borracha são detectadas em seringais comerciais, causados pela influência dos portaenxertos utilizados. Com base nesse impedimento e na importância econômica da cultura para o Estado de São Paulo, este trabalho teve por objetivo principal indicar as melhores combinações de clones com porta-enxertos clonais para plantio no Estado, visando-se à alta produção de borracha. Foram analisados dados de cinco anos de produção de borracha seca de um experimento em parcela subdividida com quatro repetições, desenvolvido em Pindorama (SP). Os tratamentos constaram de seis porta-enxertos (GT 1; IAN 873; PB 235; RRIM 600; RRIM 701 e sementes não-selecionadas -SNS) e seis enxertos (GT 1; IAN 873; PB 235; PR 107; RRIM 600 e RRIM 701), totalizando 36 diferentes combinações, e os métodos de análise constaram de análise de variância individual e comparação de médias. Observou-se efeito pronunciado de porta-enxertos sobre a variável analisada, bem como comportamento diferencial entre as combinações testadas. A partir dos resultados, pôde-se concluir que os porta-enxertos PB 235, GT 1 e IAN 873 foram os que proporcionaram maiores rendimentos, podendo ser recomendados com segurança para as condições do Planalto Paulista; o uso de SNS como porta-enxerto não é recomendado, pois os rendimentos foram muito baixos quando comparado aos demais porta-enxertos testados.Palavras-chave: Hevea, borracha natural, enxertia, propagação vegetativa. ABSTRACT INFLUENCE OF SIX ROOTSTOCKS ON YIELD OF SUPERIOR RUBBER TREE CLONESIn the rubber tree cultivation [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell.-Arg.], the most used propagation method is budding. The expected uniformity by using vegetative propagation is however not verified in fields commercial, because high variation for vigour and yield traits are induced by the rootstocks used. Based on this issue and on the economical importance of the rubber tree in São Paulo State, this study had as main objective the indication of the best combination of clones and rootstocks for planting in the State, aiming at high vigour and productivity. Analysed data were five years of dry rubber yield from an experiment in split-plot design with four replications, conducted at Pindorama (SP). Treatments comprised 36 different combinations, subjected to analysis of variance and mean comparions of six rootsocks and six scions. It was observed strong effects of rootstock over the anylised variables, as well as differential behaviour among the tested combinations. It was concluded that, PB 235, GT 1 and IAN 873 induced the largest yields, and should be recommended to the conditions of Planalto Paulista; the use of unselected seedlings (SNS) as rootstocks is not recommended as it showed very low yiel...

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