Exploitation of genetics for improvement of morphological traits in segregating population of underutilized ornamental herb (Catharanthus roseus (L.) G. Don)

Periwinkle (Catharanthus roseus (L.) G. Don) is a vital summer season perennial semi-shrub and multipurpose drought-resilient flower crop of the tropical region of the Indian subcontinent. This industrially dominant crop is primarily used as border, bedding and pot culture in landscaping. There is a lack of information on the genetics of important traits and its correlation with quantitative characters like flower yield and understanding the co-segregation of these traits might be useful in crop improvement. Therefore, the present study was performed using 30 F-2 segregating lines of Catharanthus developed from diallel crossing of six genetically dissimilar parents varied in many traits. Phenotyping of population was executed for 12 morphological traits. Results indicated that a significant positive association between days to flowering and plant height (0.753**), and leaf area and number of branches (0.463**) was recorded. Flowers per plant exhibit significantly positive correlation with all attributes except flower diameter (-005). The path coefficient analysis reported solely two traits, such as number of seeds per follicle (0.357) and corolla tube length (0.308) exerted positively significant direct effects on flower yield per plant. The scrutiny of principal components showed that the first three components demonstrated a cumulative variability of 70.1%. The dissipating of F-2 plants in bi-plot is impenitent to our prior reports that six inbred lines were genetically diverse and quite different for the characters under study. The current research might be useful in breeding programmes for selection and hybridization of periwinkle in future.