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2005 - 200912010 - 20111
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Author: Gayathri, G × Author: KAU × End date: 2011 × Start date: 2000 ×
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    ThesisItemOpen Access
    Heterosis breeding in sesame (Sesamum indicum L.).
    (Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2011) Gayathri, G; KAU; Dijee, Bastian
    The study entitled ‘Heterosis breeding in sesame (Sesamum indicum L.)’ was undertaken at the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara. The objectives of the study were to collect and evaluate different genotypes of sesame for morphological traits and yield attributes, to identify useful parents producing heterotic crosses and developing hybrids in sesame. The study also intended to develop male sterile lines in sesame through interspecific hybridization with Sesamum malabaricum. Sesamum indicum and Sesamum malabaricum accessions were collected from Kerala and Tamil Nadu and evaluated for their morphological traits. Wide range of variation was noticed for characters like plant height, number of days to flowering and seed yield per plant which contributed maximum to genetic divergence. The genotypes studied were grouped into six clusters. High genotypic coefficient of variation (GCV) was recorded for number of capsules per plant, plant height, seed yield per plant and number of branches per plant. High heritability with high genetic advance as per cent of mean was recorded for number of days to flowering, plant height, number of branches per plant, number of capsules per plant and seed yield per plant. This indicates that the characters are governed by additive gene effects and selection for these traits will be effective. Association analysis revealed that seed yield per plant was correlated to plant height, number of capsules per plant and number of days to flowering. Path coefficient analysis indicated maximum positive direct effect by number of capsules per plant, capsule length, plant height and 1000 seed weight on seed yield per plant. In order to develop hybrids, fourteen parents were selected based on the per se performance of the genotypes. They were crossed in line X tester mating design. Forty eight hybrid combinations obtained were raised in the field along with the parents and evaluated for their heterosis and combining ability effects. Parental genotypes AVTS-06-5, AVTS-06-10, IVTS-06-12, KYM-1, Tilak and TMV-6 were identified as high combiners based on general combining ability (gca) effects. Two combinations viz. AVTS-06-5 X KYM-1 and IVTS-06-12 X TMV-3 had significant values of per se performance, specific combining ability (sca) effects and standard heterosis for seed yield per plant. They can be evaluated for their hybrid vigour over locations and seasons. The crosses AVTS-06-5 X TMV-3, AVTS-06-5 X TMV-6 and TCR 3279A X KYM-1 have been identified as potential cross combinations for isolation of promising segregants as the parents involved in these crosses had high significant gca effects for seed yield per plant but the hybrids recorded non significant sca effects. Interspecific hybridization between S.malabaricum and S.indicum was attempted to develop male sterile lines. Seed set was noticed in three interspecific hybrids which failed to germinate due to embryo abortion. Hence these embryos were rescued and raised in vitro to obtain the hybrids.
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    ThesisItemOpen Access
    Standardisation of in vitro propogation techniques in thathiri (Woodfordia fruticosa (L.) Kurz.)
    (College of Horticulture, Vellanikkara, 2005) Gayathri, G; KAU; Arya, K
    The present study ‘Standardisation of in vitro propagation techniques in thathiri [Woodfordia fruticosa (L.) Kurz.]’ was undertaken in the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara during 2003-2005 through the conduct of two experiments viz. (i) direct regeneration and (ii) regeneration through callus mediated organogenesis. SH medium was found to be the best basal medium for in vitro culture of thathiri. Shoot tips were the best explants for direct organogenesis and nodal segments were used as explants for indirect organogenesis. Surface sterilization of the explants was done by soaking them in 70 per cent alcohol for two minutes followed by soaking them in 0.1 per cent HgCl2 for five minutes. One subculturing three days after inoculation checked the polyphenol interference. Multiple shoot induction was obtained when shoot tips were cultured in medium supplemented with BAP 0.5 mg/l and NAA 0.5 mg/l. The shoot elongation was best in media with BAP 0.2mg/l. Callus formation in the nodal explants of thathiri was best in media with NAA 0.5 mg/l while callus regeneration was superior in media containing BAP 0.5 mg/l and NAA 0.5 mg/l. The best response in rooting was observed in media with IBA 0.2 mg/l. Rooted plants were hardened in earthen pots containing sterile sand and covered with polythene cover. After four weeks they were transferred to larger pots in the main field.