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Relationships among yield, girth and some structural characters of the laticiferous system in young seedlings of Rubber trees (Hevea)

Paulo de Souza Gonçalves^I; Antonio Lúcio Mello Martins^II; Nelson Bortoletto^III; Alderley Zani Carvalho^IV

^IPrograma Seringueira, Divisão de Plantas Industriais (DPI) do Instituto Agronômico de Campinas (IAC), Caixa Postal 28, 13001-970 Campinas, SP, Brasil. Send correspondence to P.S.G.
^IIEstação Experimental de Pindorama, Divisão de Estações Experimentais (DEE) do IAC, Caixa Postal 24, 15830 Pindorama, SP, Brasil
^IIIEstação Experimental de Votuporanga, DEE do IAC, Caixa Postal 401, Votuporanga, SP, Brasil
^IVEstagiário do Programa Seringueira da DPI

ABSTRACT

The aim of the present investigation was to examine the relationship between growth, yield and characters of the laticiferous system of seedlings at the nursery stage. The main objectives were to seek information concerning the extent these characters are independent of each other and establish among the studied characters the principal ones that determine the yield.
Thirty seedlings at the nursery stage of [Hevea brasiliensis (Willd. ex Adr. de Juss.) Müell.Arg.], with yield levels ranging from high to low, were evaluated for juvenile growth (G), yield (Y) and bark structural characters to identify early selection parameters. The bark structural characters studied were: bark thickness (BT), total number of latex vessel rings (LV), overall density of latex vessels per ring per five square millimeters of bark (DV), average diameter of latex vessels (DL) and average distance between consecutive latex vessel rings (AD). The results showed significant linear correlations between Y and LV or DV. No correlations were detected, however, between Y and G or BT. The correlations between G and BT were positive and significant. Multiple regression studies of Y on DV, LV, DL, BT and G suggest that DV and DL, through non-significant, jointly accounted for 49% of the variation on Y. When G was used as the dependent variable, with BT and DV as independent variables, BT was the only important and significant variable, accounting for 41% of the variation on G. Studies of LV on AD or Y, shows that AD and Y were the dominant and significant variables accounting for 39% and 17% of the variation in LV. Girth and bark thickness do not appear to give significant positive predictive power for LV.

Keywords: laticiferous system; young seedlings; Rubber trees.

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