Ploidy level variation and phenotypic evaluation of turmeric (Curcuma longa L.) diversity panel

Turmeric (Curcuma longa L.) is an economically valuable spice crop widely utilized for its culinary and medicinal properties. It is mainly regarded as a triploid and is commonly propagated vegetatively by rhizomes. But occasional seed setting and open pollinated progenies have been reported in this crop. Understanding of genetic variability in conjunction with ploidy level offers insights into the multifaceted diversity existing in the crop. In this study, we carried out the phenotypic evaluation of turmeric diversity panel consisting of 93 turmeric genotypes and estimated their ploidy levels using flow cytometry. Phenotypic characterization was based on 25 characters that includes the general plant morphological characters, rhizome characters, yield and curcuminoids content. Flow cytometry is a potent and convenient method for ploidy level determination across plant species. Flow cytometric analysis revealed that among the 93 genotypes, majority were triploids (84) and nine were tetraploids. Most of the tetraploids have origins as seedling progenies while few are germplasm collection. Phenotypic characterization revealed significant genetic variation among 93 genotypes. It was found that triploids and tetraploids differ significantly in their plant height, number of shoots, number of leaves on main shoot, petiole length, leaf length, length of mother rhizome, length of primary rhizomes, length of secondary rhizomes, girth of secondary rhizomes, inner core diameter of primary rhizome, weight of mother rhizomes per plant, weight of primary rhizomes per plant, rhizome weight per plant and dry rhizome weight per plant. Further, variability analysis revealed that the characters, number of shoots per plant, length of mother rhizome, weight of mother rhizomes per plant, weight of rhizome per plant and dry weight of rhizome per plant were the most important traits with high genotypic coefficient of variation, phenotypic coefficient of variation, heritability and genetic advance for selection across ploidy levels. This is the first report of phenotypic evaluation of large turmeric diversity panel combined with ploidy level. As the ploidy information helps in development and selection of suitable seedling progenies in turmeric, this helps to improve clonal selection by enhancing variation.