Abstract
Latex yield and six anatomical bark traits were measured in a five-year-old rubber tree clonal trial planted in Itubera (Bahia, Brazil), on forty-nine different clones. The clones were pre-selected for resistance to SALB (South American Leaf Blight) caused by the fungus Microcyclus ulei (P.Henn.) v. Arx. The studied traits were : average yield (AY), girth (SC), virgen bark thickness (BT), total number of latex vessel rings (NR), average density of latex vessel per ring (DV), average diameter of latex vessels (DL) and average distance between consecutive latex vessel rings (AD). Phenotypic, genotypic and environmental correlations, and coefficient of genetic prediction (CGP) were calculated for all characters. There were considerable genetic variations between clones for AY, NR and BT, as indicated by high values of CGP. The genetic correlations were significant between AY and NR. The possibility to use NR as predictor of AY is discussed and the expected gains in percent of several references for AY are computed. FDR 4575, FDR 6099, FDR 5240, FDR 2010, FDR5597, CDC308, FDR 4151, CDC 943, MDX 608 clones were retained for their potential yield and recommended for multilocation large scale trials.
Highlights
The first breeding projects for selection of South American leaf Bligh (SALB) resistant clones caused by the fungus, Microcyclus ulei (P.Henn) v.Arx., foliar pathogen of rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell-Arg.], were developed in Latin America by the Ford Motor Company (Holliday, 1970; Sérier, 1993)
Genetic variability was assured by progenies from an F clones set (Ford prospection in the Amazonian basin), an Fx set, an IAN set, an MDF set, and a TU set
The objective of this article is to present a synthesis on clonal information concerning early tests for yield and characters from the laticiferous system originated from SALB resistant clones
Summary
The first breeding projects for selection of South American leaf Bligh (SALB) resistant clones caused by the fungus, Microcyclus ulei (P.Henn) v.Arx., foliar pathogen of rubber tree [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell-Arg.], were developed in Latin America by the Ford Motor Company (Holliday, 1970; Sérier, 1993). The first breeding projects for selection of South American leaf Bligh (SALB) resistant clones caused by the fungus, Microcyclus ulei (P.Henn) v.Arx., foliar pathogen of rubber tree [Hevea brasiliensis Ex Adr. de Juss.) Muell-Arg.], were developed in Latin America by the Ford Motor Company (Holliday, 1970; Sérier, 1993). In 1928, in an attempt to bypass the British monopoly on natural rubber, the Ford Motor Company began a rubber tree plantation program near Tapajoz river (Para, Brazil). From the year 1947, Firestone participated actively in the SALB resistant clone breeding program and collaborated with the exchanges of germplasm in Latin America. Genetic variability was assured by progenies from an F clones set (Ford prospection in the Amazonian basin), an Fx set (cross of F resistant clones with Asiatic high yielding clones), an IAN set (selection of Instituto Agronomico do Norte), an MDF set (selection on 25000 seedlings evaluated for SALB resistance and yield in Peru), and a TU set (selection of seedlings in the plantation of Turrialba in Costa Rica)
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