Journal of Biological Sciences1727-30481812-5719Asian Network for Scientific Information10.3923/jbs.2014.183.194Tectona grandis)]]>BahtiarEffendi Tri DarwisAtmawi 32014143Sigmoid curve was well known as a general curve to fit the
growth behavior of cell, organism, or population in accordance with limitation
of genetic, environmental capacity and density in their habitat. Unfortunately,
many growth behaviors did not follow the basic sigmoid curve because the prerequisite
assumptions were not fulfilled by actual condition. In this study, linear and
nonlinear function were used to modify the exponential curve become a new growth
curve which could be used in more general cases than available model nowadays.
Linear modification developed basic sigmoid curve. Nonlinear functions were
proposed to modify the exponential curve in this study were named after: Second
order polynomial (quadratic), logarithm and second order logarithm. Basic sigmoid
curve and logarithm modification on exponential curve resulted curve which always
had one asymptote line so it was suitable for fitting the fiber length data
at every growth ring if the samples were completely made from juvenile and mature
period. If the samples came from the juvenile period alone or the researcher
had not certainly sure yet, quadratic or second order logarithm modification
were highly recommended to be used because those equations could result two,
one, or none asymptote line. Second order logarithm was generally become the
best one among others. Mathematical curve fitting on fiber length growth in
this study was successfully pointed the transitional age of juvenile/mature
period of Teakwood with high coefficient of determination and low standard deviation.
Based on recommended mathematical method, the transitional age of Teakwood was
9-12 years old. It was more precise than visual assessment conducted by 30 undergraduate
students in wood science and technology class in Bogor Agricultural University
which resulted 7-15 years old. The mathematical method reduced the subjectivity
and variability compared to visual assessment.]]>Bailey, I.W.,1920Bath, M. and L.G. Mansson,2007Bowyer, J.L., R. Shmulsky and J.G. Haygreen,2003Cameron, A.D., S.L. Lee, A.K. Livingston and J.A. Petty,2005Daniels Jr., F. and J.D. Imbrie,1958Firmanti, A., E.T. Bahtiar, S. Surjokusumo, K. Komatsu and S. Kawai,2005Judd, D.B.,1952Kucharavy, D. and R. De Guio,2007Philipson, W.R. and B.G. Butterfield,1968Piazza, M. and M. Riggio,2008Pielou, E.C.,1977Tsoularis, A. and J. Wallace,2002Wu, Y.C., H.J. Yang, C.C. Yuan and K.C. Chao,2006