Use of regression analysis in plant cell, tissue, and organ culture experiments

Abstract

Several authors have suggested that plant biotechnologists perform regression or trend analysis to compare means of related quantitative treatments (e.g., doses of inositol). The present paper compares two statistical strategies to determine the effect of inositol (0-400 mg l-1) on proteolytic activity in the culture medium during pineapple growth in temporary immersion bioreactors. Strategy 1 involved one-way analysis of variance (ANOVA) followed by Tukey's Honestly Significant Difference (HSD). Strategy 2 consisted in the development of different regression analyses to determine the best fit equations to describe the experimental results. Curvefit software (version 2.10-0, May 15, 1987, Thomas S. Cox) was used. Cauchy, Normal, Parabola, and Hoerl equations were the best fitted according to their determination coefficients (R2). The optimal inositol concentrations to increase proteolytic activity were determined from the equations. Quite different results were obtained following strategy 2: 126.76 mg l-1 inositol from Cauchy, 131.29 mg l-1 from Normal, 145.06 mg l-1 from Parabola, and 14.05 mg l-1 from Hoerl equations. In contrast, experimental data identified 200 mg l-1 inositol as the most adequate concentration to increase proteolytic activity in the culture medium. The statistical strategy 1, one-way ANOVA followed by Tukey HSD clearly supported this biological observation. In this paper, regression analysis was not useful to describe our experimental results. © 2007 The Society for In Vitro Biology.