Author(s):

Maliha A, M Balram, Ch V Durgarani, Y Chandramohan and T Ramesh

Abstract: Rice is staple food for every second person on the globe but its cultivation demands a very high proportion of agricultural water available on earth. With the current trends of water usage and cultivation practices followed for rice, soon the water would become a scarce resource. Among the alternative methods available for cultivation of paddy with limited water, aerobic rice cultivation is the most economically and environmentally feasible option. Systematic breeding programs for aerobic rice varieties have been very few thus allowing a very narrow understanding about the genetic diversity present among rice lines that can be good candidates for aerobic cultivation. Since understanding the genetic diversity of a set of lines is pre-requisite for a successful breeding program, this study has been conducted using 110 germplasm lines collected from different parts of the country and a set of 58 SSR markers were used for polymorphism. Out of 58 markers used, 40 were found to be polymorphic thus making the overall polymorphism percentage 69.0%. The polymorphism percentage ranged from 55.6% (Chr. 12) to 100% (Chr. 8). The PIC (Polymorphism Information Content) values for the polymorphic markers ranged from 0.55 (RM525) to 0.98 (RM488) with an average of 0.84. Number of alleles recorded per marker ranged from minimum 2 to maximum 4 (average 2.63 alleles) and the total number of alleles scored is 105. A total of three markers (RM572, RM1367 and RM38) showed presence of alleles of four different sizes in the germplasm. Out of the remaining markers, 19 markers had 3 alleles each and 18 markers had 2 alleles each. As a result of diversity analysis the genotypes grouped into four distinct clusters (I, II, III, IV) with 22, 9, 65 and 14 genotypes respectively which further diverged into two sub-clusters each (Ia, Ib, IIa, IIb, IIIa, IIIb, IVa, IVb). Cluster I predominantly contained varieties and landraces for irrigated conditions that were tested under aerobic cultivation in this study. Cluster II had lines that have established under aerobic situations and are also being used as competent parents for aerobic rice breeding. The third cluster with maximum number of genotypes (65) was dominated by ARC (Assam Rice Collection) lines and the last cluster was a mixture of lines suitable for aerobic cultivation and landraces from Tamilnadu. The present study is thus an attempt to understand the genetic relatedness/ diversity of rice germplasm to enable selection of diverse lines from different clusters to be used as candidates in future research towards aerobic rice breeding.

DOI: 10.22271/phyto.2020.v9.i4p.11864

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