Collection, characterization and conservation of genetic resources of native turmeric (Curcuma longa. L) landraces from Nepal

Turmeric is a profitable cash crop and the main source of income for the farmers of the tropical midhills in Nepal. A field experiment was carried out at the field genebank block of National Agriculture Genetic Resources Centre (NAGRC), NARC, with the aim of evaluating the agro-morphological traits and assessing the phenotypic diversity of turmeric landraces. This study involved the collection of 136 landraces from 62 districts across Nepal, characterized by an augmented block design. Thirteen quantitative and twelve qualitative traits were recorded and analyzed using R software, version 4.5. The Shannon–Weaver index revealed that qualitative traits exhibited a diversity range from low to high (0.19-0.99), while quantitative traits showed moderate to high diversity (0.38-0.91). The top three principal components accounted for 80.29% of the total phenotypic variation, with two components explaining 72.31%, primarily driven by plant height, leaf lamina length, rhizome breadth, petiole length, leaf lamina width, rhizome length, rhizome girth, rhizome weight and internode length. The cluster analysis divided the 136 accessions into two separate groups, with Cluster-1 being the largest, comprising 62.5% of the accessions, and Cluster-2 being the smaller group, representing 37.5% accessions. The phenotypic path analysis resolved that all of the traits showed a positive linear effect on the total yield except number of mother rhizomes, with an R squared value of 45.5%. The preliminary findings showed that NGRV0251, NGRV0179, and NGRV0219 were candidate landraces for the breeding program, as they were superior in terms of rhizome weight, number of mother rhizomes and total yield.