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20201
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Subject: Genetics and Plant Breeding × Author: Akhil, K P × End date: 2020 × Start date: 2020 ×
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    ThesisItemOpen Access
    Genetics of shattering resistance in rice (Oryza sativa L.)
    (Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2020) Akhil, K P; KAU; Biju, S
    Rice is the staple food crop of Kerala. Among the plethora of rice varieties available Jyothi is by far the most popular in the state owing to its consumer preference. Easy seed shattering leads to significant loss in Jyothi which can be overcome by transferring shattering resistance to it. Screening of genotypes for shattering resistance identified donors like Athira and Triveni with good combining ability. The present experiment was thus envisaged to transfer shattering resistance to Jyothi from the donors and to study the nature of inheritance of seed shattering trait using six parameter model of generation mean analysis. Observations were recorded in the two crosses viz., Jyothi x Aathira and Jyothi x Triveni for eleven quantitative characters viz. days to 50 per cent flowering, plant height, tillers per plant, panicles per plant, panicle length, spikelets per panicle, seeds per panicle, days to maturity, test weight, grain yield per plant and shattering per cent in six generation (P1, P2, F1, F2, B1 and B2) obtained from the two crosses. Panicle per plant, test weight, grain yield per plant and shattering per cent recorded significant heterosis in the desirable direction in both the crosses. Mean effect (m) was significant and positive for all the characters studied in both the crosses. The additive component (d) was significant and positive for days to 50 per cent flowering, tillers per plant, panicles per plant, days to maturity, grain yield per plant and shattering per cent in the cross Jyothi x Triveni while the other characters recorded significant and negative additive gene effect. The characters tillers per plant, test weight and shattering per cent showed significant positive additive gene effect in the cross Jyothi x Aathira and rest of the characters showed significant and negative additive component. Dominance gene effect was observed to be significant and negative for most of the characters studied in both the crosses. Non-allelic interactions were observed to be significant in most of the characters except days to 50 per cent flowering, tillers per plant, days to maturity and shattering per cent in the cross Jyothi x Aathira. The epistatic interaction model of generation mean analysis was found adequate for obtaining gene actions for all the characters. Among the three type of interactions dominance x dominance interaction was found to be more important for all the characters. Additive x additive and additive x dominance gene interactions were found to be equally important for most of the characters studied in both the crosses. Dominance gene effect was observed controlling the genetic variance in most of the traits studied. Presence of additive and non-additive along with epistatic interaction revealed the complex nature of inheritance of the characters. Predominant dominant gene effect along with duplicate epistasis limits the scope of direct selection. In the F2 populations characters showed high heritability in both the populations studied. Plant height, panicle length and days to maturity were found to have low genetic advance. Plant height recorded moderate genetic advance, whereas, other characters exhibited high genetic advance in F2 population derived from the cross Jyothi x Triveni. Days to maturity showed low genetic advance, days to 50 per cent flowering and panicle length recorded moderate genetic advance and other characters recorded high genetic advance in F2 population derived from the cross Jyothi x Aathira. As shattering resistance is governed predominantly by additive gene effects selection in the early segregating generations will be highly rewarding. The selected lines may be advanced to further generations to identify lines with high yield coupled with shattering resistance and can be forwarded to develop high yielding varieties with low shattering or bi-parental mating among the selected lines may be undertaken to recover superior recombinants with high yield and shattering resistance.