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2011 - 20152
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Subject: Plant Breeding × Author: KAU × End date: 2015 × Start date: 2011 × Thesis Type: Ph.D ×
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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
    Assessment and induction of variability through in vitro mutagenesis incassava (Manihot esculenta, Crantz)
    (College of Horticulture, Vellanikkara, 2015) Hilario Ernesto Magaia; KAU; Jiji Joseph
    The study entitled “Assessment and induction of variability through in vitro mutagenesis in cassava (Manihot esculenta, Crantz.)” was carried out between 2012 and 2014 in the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara. The objective of the study was to assess the genetic variability in the short duration cassava germplasm and induction of variability through in vitro mutagenesis in selected genotypes. Field evaluation, standardization of protocols for in vitro regeneration, in vitro mutagenesis and assessment of variability of in vitro mutated plants were done. Wide genetic variability existed among the collected short duration cassava genotypes. The colour of petiole and root cortex was found to be the most variable qualitative trait for above ground and tuber portions respectively. High magnitude of phenotypic and genotypic coefficient of variation along with high heritability and high genetic gain was observed for branch number, branch height, tuber fresh weight, and Cassava Mosaic Disease. All traits except tuber neck, branch number, scar number and internode length were positively correlated with fresh tuber yield. High direct contribution towards tuber yield was exerted by shoot biomass, tuber dry matter content and harvest index indicating that these are reliable predictor variables for increased yield. Among the biochemical traits, high heritability and high genetic gain was observed for HCN content, amylose content and starch content. Biochemical analysis indicated the occurrence of high starch genotypes (Sree Jaya, CC10 and CC7) suitable for industrial starch production. Vellayani Hraswa with lower starch content was more suited for food or feed purposes, than industrial purposes. The genotype CC10 with easiness in peeling, good taste after cooking and less cooking time scored maximum in organoleptic evaluation. Sree Jaya was sweet on chewing, had highest starch content, lowest HCN content and less fibre content. 213 Diversity analysis indicated that the cassava genotypes grouped into five clusters. No parallelism was found to occur between geographic distribution and genetic diversity. Selection index constructed for the identification of the best genotypes indicated that CC1 and Sree Jaya were the most promising genotypes. CC1, a farmers’ variety from Malappuram district was found to be the best genotype with respect to yield and resistance to CMD, but with a comparatively high HCN content. In vitro mutagenesis in cassava was done using the genotypes CC1 and Sree Jaya. Sterilization of cassava nodal and leaf explants was accomplished by washing with 5 per cent Teepol solution for two minutes, followed by washing for one minute with 75 per cent ethanol and washing for one minute with 0.05 per cent solution of mercuric chloride. Friable embryogenic callus (FEC) for both CC1 and Sree Jaya genotypes was obtained from immature leaf explants cultured in MS media with 3.0 per cent sucrose (MS3), either with 6.0 to 8.0 mg l-1 of 2,4- D , or with 1.0 mg l-1 BAP + 0.2 to 0.5 mg l-1 NAA. Somatic embryos for both genotypes were obtained from FEC cultured in media MS3 with 8.0 to 10.0 mg l-1 picloram and germinated into the plantlets on MS3 media with 4.0 mg l-1 BA or 0.25 mg l-1 TDZ. In vitro regeneration and multiplication from nodal explants were obtained in MS3 media containing either 0.25 mg l-1 TDZ or 2.0 mg l-1 BAP. Rooting of the in vitro plantlets was obtained in MS3 + 0.25 mg l-1 TDZ or 1/2MS1. The LD 50 value varied with the cultures used for in vitro mutagenesis. The LD 50 value for gamma radiation was 40 Gy, 30 Gy and 50 Gy for FEC, somatic embryoids and plantlets, respectively. LD 50 value for EMS was 1.20 per cent for FEC and somatic embryoids and 0.90 per cent for plantlets. Variation in response to mutagenesis was also observed between the two genotypes subjected to in vitro mutagenesis. There was significant difference in the growth characteristics of the mutagen treated in vitro cultures in both genotypes. Reduction of the number of shoots and leaves were more in CC1 compared to Sree Jaya. 214 A combination of SoilriteTM with pure sand at 1:1 proportion was the best substrate for acclimatization of the plantlets outside the tissue culture lab. Fan and pad green house was the best structure for in vitro acclimatization of plantlets resulting in 47 per cent of success rate. Variability with respect to quantitative traits like height, number of shoots and number of leaves was observed in vitro plantlets in the hardening stage. The qualitative traits like colour of the petiole, stipule, emerging leaf and of the stem and the shape of central lobe of leaves varied between the mutated plants.