Studies on Correlation and Path Analysis in Mutants of Coleus (Coleus forskohlii Briq.) for Yield and forskolin Content in V2M1 Generation

The present investigation was carried out during 2003-2007 involving terminal cuttings of coleus ecotype 'Garmai'. Genotypic correlation coefficient between yield and its components in mutants of coleus was studied, viz., plant height, number of branches plant^-1, number of leaves plant^-1, number of tubers plant^-1, tuber length and tuber girth were found to have positive and highly significant correlation with yield. However, forskolin and essential oil content showed negative correlation with yield. Path analysis of component characters on yield of Coleus in V₂M₁ generation exerted positive direct effect through the characters plant height, number of leaves plant^-1 and number of tubers plant^-1. Similarly, direct effect was observed to be negative through number of branches plant^-1 (-0.930), total amount of alkaloids (-0.066) and forskolin content (-0.026). The current investigation resulted in residual effect of 0.158 indicating the accuracy and appropriate selection of component character for crop improvement programme. Weightage must be given to component characters exhibiting positive attributes towards fresh tuber yield in Coleus. However, some traits with negative attributes are also chosen for getting improved quality, i.e., forskolin content, without much inhibition on fresh tuber yield plant^-1.