Genetic diversity, essential oil composition, and in vitro antioxidant and antimicrobial activity of Curcuma longa L. germplasm collections

Genetic divergence was estimated among sixty-five genotypes of turmeric (Curcuma longa L.) using Mahalanobis D2-statistics on thirteen agro-morphological quantitative traits. The genotypes were grouped into nine clusters. Cluster I had maximum number of genotypes (19) followed by cluster II (13), III (11), IV (5), V (4), VI (4), VII (4), VIII (3) and IX (2) in order. The genotypes which belongs to cluster VII had the maximum divergence (250.62), followed by cluster IX (244.61) and cluster VI (240.40). The highest inter-cluster distances were observed between cluster IX (1871.46) and cluster VIII (1296.51), suggesting that the genotypes included in these clusters may be used for future breeding programme. Traits like fresh weight of rhizome, dry weight of rhizome were the major contributors to the genetic divergence. The chemical composition of essential oils from eight selected genotypes of Curcuma longa L. was studied and identified by gas chromatography-mass spectrometry (GC/MS). The compounds cis-sesquisabinene hydrate (3.4%), curzerenone (0.6%), β-bisabolol (2.2%), and farnesol (1.2%) were found only in CIM Pitamber variety. The total percentage of compounds identified from the essential oil of Curcuma longa leaves was maximum in CIM Pitamber (98.1%) followed by Bhagauna (90.9%), Borai Khuwa (90%), TC 11 (86.9%), Bhagauna Baag (85.1%), CH 20 (84.3%), Paroraha JD Kola (75.4%) and JD Kola (74.8%). The antioxidant activity results demonstrated that Curcuma genotypes had marked ferric ions reducing ability and having electron donor properties for neutralising free radicals. All Curcuma genotypes exhibited bacteriostatic nature against Mycobacterium smegmatis strain, used for the screening of antitubercular activity.