Full text in pdf format
Correlations studies between plugging index, yield girth and bark thickness in Hevea clones
Paulo de Souza GonçalvesI; Mário CardosoI; Toshio IgueII; Antonio Lucio M. MartinsIII; Cezar LavorentiI
ISeção de Plantas Tropicais, Instituto Agronômico de Campinas, Caixa Postal 28, 13100 Campinas, SP, Brasil. Send correspondence to M.C.
IISeção de Estatística, Instituto Agronômico, Caixa Postal 28, 13100 Campinas, SP, Brasil
IIIEstação Experimental de Pindorama, Caixa Postal 24, 15830 Pindorama, SP, Brasil
ABSTRACT
The rubber tree, Hevea brasiliensis Muell. Arg. (Family Euphorbiaceae), which is extensively cultivated in Brazil and south-east Asia is indigenous.
Correlation studies were carried out using yield of dry rubber per tapping by Hamaker Morris-Mann test tannin (Y), plugging index (Pi), virgen bark thickness (B), mean Birth (G) and yielding index (Yi) from a fifty four month trial. Negative significant correlations between Pi and Y or Pi or Yi were found. No correlations were, detected, however, between Pi and G or B. The correlations between Y and G or Y and Yi were positive and significant. Among the other characters, significant positive correlations were found between G and B but there were no correlations between G and Yi, B and Pi or Yi. Multiple regression of Pi on Y, G, B and Yi suggest that Y was the only important and significant variable accounting for 35%; of the variation on Pi. The variables G and B do not appear to give significant positive predictive power for Pi. When Y was used as the dependent variable, with G and Pi as the independent variables, the coefficients of multiple determination (R2) varied from 0.21 to 0.43. Yi showed some additional contribution significant at P <0.01 when considered together with G.
Keywords: Correlations studies; Plugging index; Yield girth; Bark thickness; Hevea.
REFERENCES
Hamaker, C.M. (1914). Plantwijdte en uitdunning bij Hevea. Prac-advies verslagen van het. In: International Rubber Congress. s.l.
Ho, C.Y. (1972). Investigations on shortening the generative cycle for yield improvement in Hevea brasiliensis. Masters Thesis, Cornell University, N.Y.
Ho, C.Y. (1976). Clonal characters determining the yield of Hevea brasiliensis. In: Proceedings of International Rubber Conference, (Kuala Lumpur, 1975). pp. 27-38.
Milford, G.F.J., Paardekooper, E.C. and Ho, C.Y. (1969). Latex vessel plugging: Its importance to yield and clonal behavior. J. Rubb. Res. Inst. Malaya 21: 274-279.
Morris, L.E. and Mann, C.E.T. (1932). Selection and breeding. Early determination of yielding qualities of seedling. Annual Report 1931, Kuala Lumpur, Rubber Research Institute of Malaya. Botanical Division, p. 166-168.
Narayanan, R. and Abraham, P.D. (1976). Latex vessel plugging indices and their variations for clones, sites and tapping systems. J. Rubb. Res. Inst. Malaysia 24: 248-260.
Narayanan, R., Gomez, J.B. and Chen, K.T. (1973). Some structural factors affecting the productivity of Hevea brasiliensis. Il. Correlation studies between structural factors and yield. J. Rubb. Res. Inst. Malaysia 23: 285-297,
Narayanan, R., Ho, C.Y. and Chen, K.T. (1974). Clonal nursery studies in Hevea. III. Correlations between yield, structural characters, latex constituints and plugging index. J. Rubb. Res. Inst. Malaysia 24: 1-14.
Paardekooper, E.C. and Samosorn, S. (1969). Clonal variation in latex flow pattern. J. Rubb. Res. Inst. Malaya 21: 264-272.
Paardekooper, E.C. and Sookmark, S. (1969). Diurnal variation in latex yield. J. Rubb. Res. Inst. Malaya 21: 341-347.
Simmonds, N.W. (1969). Genetical bases of plant breeding. J. Res. Inst. Malaya 21: 1-10.
Tan, H. (1987). Strategies in rubber tree breeding. In: Improving vegetatively propagated crops (Abbot, A.J. and Atkin, R.K., eds.). London, Academic Press. pp. 27-62.
Tan, H. and Subramanian, S. (1975). A five-parent diallel cross analysis for certain characters of young Hevea seedlings. Proc. Int. Rubb. Conf. Kuala Lumpur, vol. II, pp. 13-25.
Wycherley, P.R. (1976). Tapping and partition. J. Rubb. Res. Inst. Malaysia 24: 169-194.