Molecular diversity and heterosis studies based upon Ogura CMS system in Indian mustard
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Date
2020-01
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CCSHAU, Hisar
Abstract
Realizing the potential of hybrids in increasing the productivity of Indian mustard, the present study was conducted during Rabi 2016-17 and Rabi 2017-18at Oilseeds Research Area, Department of Genetics and Plant Breeding, CCS Haryana Agricultural University, Hisar to estimate the extent of heterosis in the Ogura CMS based crosses, identification of crosses with good general and specific combining ability, diversity analysis at molecular level among 45 genotypes including five CMS lines and 40 restorers and to optimize the planting ratio of A and R lines for economic hybrid seed production. For heterosis analysis, 50 crosses were developed by crossing five Ogura CMS lines with ten restorers in L x T fashion. A total 65 genotypes including (50 hybrids, 15 parents and three checks) were evaluated for 12 different traits in RBD in three replications. Analysis of variance revealed sufficient differences among lines, testers and crosses for most traits.
Line RH 0555-OA and tester IOR-12 were found as good general combiners possessing highly significant positive GCA effects for seed yield and component traits. Crosses viz., RH 0555-OA × IOR-12, RH 0555-OA × IOR-1, RH 0555-OA × IOR-19 and RH 30-OA × IOR-1 were observed with significant positive economic heterosis over commercial check DMH 1 for seed yield per plant. These crosses may be considered as most promising for further testing in hybrid trails.
Fifty eight SSR primers were used for molecular diversity analysis among 45 genotypes (5 CMS +40 restorers). Out of 58 primers, 33 primers were found polymorphic. A total of 95 alleles were detected across all the 45 genotypes. The PCR amplified products ranged from 70 bp to 350 bp in size. The number of alleles per locus varied from 2 to 5 with an average of 2.89. The PIC value varied from 0.206 to 0.749 with an average of 0.519. The highest PIC value was obtained for BG 132 (0.749) followed by BG 114 (0.744). Forty five genotypes were distributed into six groups where three groups had a single genotype (restorer line) each. Cluster VI consisted of all five Ogura CMS lines only. In remaining clusters, restorer lines were distributed. Based on similarity coefficient, cross combinations viz., RH 0749-OA & IOR-17, RH 0749-OA & IOR-20 and RH 119-OA & OR-17 were identified as diverse and may be suitable for heterosis exploitation.
To find out optimum planting ratio for hybrid seed production two CMS lines along with one common restorer were grown in five planting ratios viz., 2:1, 3:1, 4:1, 5:1 and 6:1. The ANOVA revealed significant differences due to different ratios for characters viz., number of siliqua on main shoot, siliqua length (cm), number of seeds/siliqua, seed yield /plant (g) and seed yield per plot (kg/ha). Among all five planting ratios, 2:1 was superior for seed yield and its related characters but it was statistically at par with 3:1 ratio and therefore 3:1 was observed as optimum ratio(A:R) for economic hybrid seed production at large scale.