Plant Growth Analysis: The Use of the Richards Function as an Alternative to Polynomial Exponentials

The derived quantities in plant growth analysis, obtained byfitting the Richards function on the one hand and polynomialexponential functions on the other hand, are compared, usingtwo sets of experimental data. Results show that, although thereis rarely a statistical difference between the quantities derivedfrom the two types of function, the time trends are often morebiologically meaningful when derived from Richards functionfittings. Further, use of the Richards function does not entaila problem of choice, as occurs in the use of polynomial exponentialswhen particular members of the family must be selected for givendata sets; on the other hand, the Richards function will notfit those few sets of growth data which show insufficient curvaturetowards an upper asymptote. It is recommended that, wheneverpossible, the Richards function be used in plant growth analysisinstead of polynomial exponentials. Triticum aestivum L., wheat, Helianthus annuus L., sunflower, growth analysis, Richards function