Molecular diversity analysis and genetics of some morpho physiological and biochemical traits associated with moisture-stress tolerance in bread wheat (Triticum aestivum L.)
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Date
2023-03-25
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CSK HPKV, Palampur
Abstract
The present investigation entitled ‘Molecular diversity analysis and genetics of some morpho-physiological and
biochemical traits associated with moisture-stress-tolerance in bread wheat (Triticum aestivum L.)’ was conducted
to identify morpho-physiological and biochemical traits associated with moisture-stress tolerance and analyze
genetic diversity at morphological and molecular level. Experimental material for diversity studies comprised of 56
genetically diverse wheat genotypes; including some high yielding, drought tolerant lines, synthetics, local
collections, recombinant inbred lines of a drought tolerant cultivar C 306. Experimental lines were evaluated for
different traits in alpha-RBD design with three replications under irrigated (E1) and moisture-stress (E2) field
conditions during Rabi 2017-18. A modified TTC analysis comprising 48 progenies; 16 lines and 3 testers was
conducted under controlled irrigated (E1) and moisture-stress (E2) conditions during Rabi 2018-19. Significant
genetic variability was observed for days to 50% flowering, flag leaf area (FLA), specific leaf area (SLA), specific
leaf weight (SLW), relative water content (RWC), grain growth rate I (GGR-I), grain growth rate II (GGR-II), stem
reserve mobilisation (SRM), tillers/ plant, grains/ spike, 1000-grain weight, biological yield/ plant, dry matter
accumulation (DMA), grain yield/ plant, harvest index and proline content. High phenotypic coefficient of
variation (PCV) and genotypic coefficient of variation (GCV) along with high heritability and moderate genetic
advance were recorded for proline content under E1 and E2. Grain yield/plant showed significant positive
correlation with tillers/plant, 1000-grain weight, biological yield/plant, DMA and harvest index. Biological yield/
plant and harvest index appeared to be the best selection indices for increasing grain yield owing to high direct and
indirect effects of these traits in path analysis. Under E1 first six principal components revealed 72.40 % and under
E2 first five components explained 71.6 % of total variability. Variation for proline content contributed the
maximum to the observed genetic divergence under both conditions. Congruence between morpho-phyiological
and SSR data was observed under both the environments. Forty-six out of 56 test genotypes were common among
molecular and morphological clusters under moisture-stress, whereas 39 genotypes were common under irrigated
conditions. Genotypes SYN 105, IC 36737, HS 562, IC 594376 and VL 907 under irrigated conditions and
genotypes viz. IC 322025, HS 490, VHC 6081, VHC 6127, SYN 103, VL 892, VHC 6413, C 306, VL 907, HPW
236 and SYN 117 under moisture-stress conditions were most diverse. STRUCTURE divided the experimental
lines into two major populations. Modified TTC analysis was used to detect epistasis and estimates of additive and
dominance components of variance for observed phenotypes, which indicated that mean squares due to epistasis
were significant for all the traits except SLW and relative water content under irrigated conditions (E1) and FLA
under (E2). Additive × Additive (i) type interactions were significant for GGR-I and tillers/ plant under E1 and E2
conditions while j+l type interactions were significant for all the traits except SLW and RWC under irrigated
conditions (E1) and RWC under E2. The average degree of dominance (H/D)1/2 revealed similar gene action for
1000-grain weight and GGR-II under both E1 and E2. The comparison of estimates of genetic parameters using
Line × Tester and Triple test cross indicated the role of overdominance in genetic control of traits namely,
grains/spike, grain growth rate I and proline content under both the environments E1 and E2. Combining ability
analysis revealed VHC 6413, HS 562, NIAW 1415, WH 1105 as good general combiners for FLA, GGR- II,
grains/ spike, 1000-grain weight; Syntehtic 107 and NIAW 1415 for SRM; VHC 6081 and VHC 6127 for
tillers/plant; HS 490,VHC 6127 and HS 507 for DMA; VHC 6127, HS 490, NIAW 1415 and NI 5439 for grain
yield/plant; HS 562 and Synthetic 107 for harvest index; HS 507, Synthetic 107, Synthetic 112 and NIAW 1415
for proline content under both E1 and E2. HPW 89 x VL 907 recorded positive significant SCA effects for GGR- II;
HPW 349 × VL 907 and HS 562 × HPW 368 for stem reserve mobilisation and VHC 6127 × HPW 368 for
grains/spike and dry matter accumulation. These crosses were found promising and could be utilized for
developing high yielding drought tolerant lines.