J. JOHNNY SUBAKAR IVIN, Y. ANBUSELVAM, S. JEEVITHA, V. KANNAN1 AND R. ANANDAN*
Department of Genetics & Plant Breeding, Faculty of Agriculture, Annamalai University, Annamalai Nagar-608 002
(Tamil Nadu), India
*(e-mail : bioanandan@gmail.com; Mobile : 96263 31366)
(Received : January 11, 2022; Accepted : March 15, 2022)
ABSTRACT
The present study was undertaken to evaluate 28 traditional rice genotypes for various physiomorphological characters towards drought tolerance. Two experiments were conducted to assess the
responsiveness of genotypes for induced moisture stress. Field level screening for drought stress was
carried at three different environments and the pooled data were subjected to D2 Mahalonobis analysis
of genetic divergence. In second experiment, laboratory screening at growth stages was subjected to
four levels (0, 20, 30 and 35%) of polyethylene glycol (PEG-6000). Data on seed germination percentage,
shoot length, root length and dry weight were recorded. Most of the genotypes showed significant
differential responses for growth parameters towards the increasing concentration of PEG. Among the
28 genotypes, Kuzhiadichan, Karupu Kavuni, Mysore Malli, Sornamasuri and Raja pokame recorded
better growth parameters under drought stress conditions indicating their capability to combat with
severe moisture situation. Using D2 analysis, the 28 rice genotypes were grouped into 10 clusters. The
maximum intra-cluster distance was observed between Cluster I and Cluster VII. The maximum intercluster distance was noticed between clusters III and X. It showed that intra-cluster distances were
significantly lower than the inter-cluster distances indicating the existence of wider genetic diversity
among the genotypes. Genotypic correlation studies revealed that grain yield had positive significant
correlation with productive tillers, grains per panicle and 100-seed weight. Grain yield exhibited positive
significant association with number of productive tillers per plant, number of grains per panicle and
100-seed weight, while it was negatively correlated with days to 50% flowering. The genotypes Karudan
samba, Kichadi samba, Kattuyanam, Karupukavuni, Mapillai samba, Kuzhiadichan and Thanga samba
showed superior values in terms of grain yield under drought stress. It was/is advantageous to select
genotypes as donor parents from clusters showing high inter-cluster distance (Clusters III and X) for
crop breeding program.
Key words : Rice, polyethylene glycol, drought tolerance, cluster