A Power Parabola for an Asymmetrical Response
- Carol J. Adams and
- F. J. Hills2
As plant density increases, crop yield often increases, reaches a plateau, then decreases at a different rate. It is difficult to find a simple equation that will adequately describe this situation. A FORTRAN IV program is presented which can be used to fit a parabola to such an asymmetrical response by the transformation of abscissa and ordinate values to calculated powers, i.e. Yw = a + bXz + c(Xz)2. The procedure is illustrated with the response of sugar beet (Beta vulgaris L.) root yield to plant density in field plots and resulted in a power parabola of excellent fit (R2 = 0.955).Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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