Evaluation of drought tolerance potential in early generation progenies of sugarcane (Saccharum Sp. Complex)
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Date
2018-08
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
The present investigation entitled “Evaluation of drought tolerance potential in early generation progenies of sugarcane (Saccharum Sp. Complex)” was conducted with 65 Bi-parental progenies along with parents and six check varieties viz., Co 0238, Co J 64 and Co Pant 03220 (early) and Co Pant 97222, Co Pant 05224, CoS 8436 (mid-late) to investigate drought tolerance potential based on physio-biochemical characters, studies on genetic parameters and revalidation of candidate gene specific molecular markers to aid breeding programme. The experiment was conducted in augmented block design- II in two seasons with two environments such as control at N.E.B.C.R.C. and stress at P. C.P.G.R. G.B.P.U.A&T, Pantnagar during spring 2017 and autumn 2017-18. The drought stress was created by withdrawing the irrigations during the 50 DAS to 200 DAS. The data was recorded on 16 physiological and biochemical characters for estimation of genetic parameters, genetic diversity analysis and selection indices. Further, Twenty five selected clones were utilized for candidate gene specific molecular markers validation study at Plant Biotechnology lab, Department of Genetics and Plant Breeding. Analysis of Variance (ANOVA) for four environments revealed that traits like proline content and leaf firing exhibited significant differences in stress unlike control environment indicating that these traits are of very high utility in selection for drought tolerance. The effect of water stress was clearly reflected by the reduced mean values for almost all the traits except an increase in proline content under stress. High PCV and GCV along with high heritability and high genetic advance as percent of mean was observed for CTD 60, CTD 120, CTD 180, Chl a, Chl b, Total chlorophyll, Total carotenoids Proline content, RWC % and Leaf firing indicating the prevalence of additive gene action in expression of these characters. Estimates of path coefficients revealed that Traits like Chl a, Chl b, total chlorophyll, SPAD 120, SPAD 180 and proline content were found to confer positive direct as well as indirect effects on DTC which supports their utilization as a reliable tool in selection for drought tolerance in sugarcane. Under both the environmental conditions highest inter-cluster distances were found to be between a drought tolerant cluster and a drought sensitive cluster. Cluster I, III and IV were found to comprise desirable clones for most of the traits. Germination percent, Chl a, RWC percent, leaf firing, total carotenoids, SPAD 60, Chl b, DTC and proline content contributed approximately 70 percent of the total divergence. Based on the selection scores the genotypes namely PC (2015-16)-55, PC (2015-16)-26, PC (2015-16)-40, PC (2015-16)-54, and PC (2015-16)-1 were found best ones among drought tolerant genotypes. Validation analysis of the marker trait association with respect to candidate gene specific markers and drought tolerance through t-test revealed that four markers DREB 1A, NAC 2, Snac 1 and LEA 3 recorded significant difference between the means of the two groups. The significant association proves their worth for future use of these markers in marker-assisted selection for drought tolerance in sugarcane.
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