Dummy variable approach for analysing yield response of plant genotypes to nitrogen levels: case study of tomato

Abstract

For analysing the data from field experiments involving qualitative and quantitative variables, a new approach of using dummy variables for qualitative variables in the regression equation was tried in with the help of two years data from the experiments conducted on tomato crop involving four genotypes and four nitrogen levels. The results of analysis showed that using dummy variables for qualitative variable viz., genotypes in the regression analysis has the advantage of single equation taking care of differences between genotypes as well as their individual contribution to yield along with other quantifiable inputs ake nitrogen. Besides having comparable predicting efficiency of yield with that of individual functions for each genotype based on ANOVA, dummy variable approach saves a lot of time and labour especially when a number of genotypes are involved in the experiment, as otherwise a separate equation has to be fitted for each genotype to catch their effect on yield.