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ThesisItem Open Access Genetic analysis of high yielding rice varieties of diverse origin(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 1998) Vanaja, T; KAU; Luckins, C BabuThe research project 'Genetic Analysis of High Yielding Rice Varieties of Diverse Origin' was carried out in the College of. Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur during the period 1995-'98. The major objectives of the study were to understand the genetic architecture of high yielding rice varieties of diverse origin so as to evolve appropriate breeding methodology, to isolate promising lines having the new ideotype concepts from the segregating generations and to identify alternative source of cytoplasmic male sterile system suitable to warm humid climatic conditions experienced in Kerala. The study, about components of heritable variation revealed that the characters, number of panicles m-2 number of tertiary branches panicle-1, yield ha-1, spikelet sterility percentage and alkali spreading value exhibited high broad sense heritability coupled with high expected genetic advance and high genotypic coefficient of variation. High broad sense heritability and high expected genetic advance coupled with moderate genotypic coefficient of variation were manifested by the characters, namely, height of plant at harvest, second uppermost internodal length, length of flag leaf, ratio of vegetative phase to reproductive phase, number of spikelets panicle-1 number of grains panicle-1, LIB ratio of grain, milling percentage, amylose content, volume expansion ratio and water uptake. '1 Correlation studies revealed that the principal yield determining components in rice are harvest index, number of tertiary branches panicle-1 number of panicles m-2 number of grains panicle-1 number of spikelets panicle-1. ratio of vegetative phase to reproductive phase, 1000 grain weight, number of days to 50 per cent flowering, number of days to harvest and spikelet sterility percentage. While selecting genotypes for higher yield potential, emphasis should be given for comparatively long vegetative period, short period from panicle initiation to 50 per cent flowering and long ripening period. A selection model was formulated consisting of the characters, namely, yield ha-1 harvest index, number of days to harvest, number of tertiary branches panicle-1 ratio of vegetative phase to reproductive phase and number of grains panicle-1 Cluster analysis revealed that there was no parallelism between geographical distribution and genetic diversity. The 56 genotypes representing different eco-geographical regions were grouped into nine clusters based on genetic distances. Combining ability studies showed that both additive and non-additive gene effects were important, with predominance of non-additive gene action, for all the characters except for 1000 grain weight, second uppermost internodal length and height of plant at harvest. The varieties Vytilla3, Mahsuri, Mattatriveni and Karthika were identified as good general combiners. The varieties Mahsuri, Karthika, Vytilla 3, Mattatriveni and IR62030-18-2-2 showed pronounced cytoplasmic effect on yield and various yield contributing characters. The crosses Vytilla 3 x Mattatriveni, Mahsuri x Vytilla-3 an,d Mahsuri x Mattatriveni are recommended for recombination breeding. The crosses Vytilla 3 x IR36, Vytilla 3 x IR60133-184-3-2, PK3355-5-1-4 x Bhadra, Vytilla 3 x Mattatriveni, Karthika x Bhadra, PK3355-5-1-4 x Karthika and PK3355-5-1-4 x IR620'30-18-2-2 are recommended for heterosis breeding. The cytoplasm of Vytilla 3 (an improved saline tolerant variety of Kerala) was identified as an alternative source for cytoplasmic male sterility in rice, suitable to warm humid tropical climate, experienced in Kerala. The varieties IR36 (international check) and Hraswa (extra short duration high yielding variety of Kerala) are the proposed maintainer lines. Mattatriveni is the proposed restorer line for the proposed IR36 'A’ line and Hraswa 'A’ line. The generation mean analysis using six parameter model revealed that both additive and non-additive gene effects played an important role in the inheritance of yield and important yield components, with predominance of dominance, additive x additive and dominance x dominance type of gene effects. Results of inbreeding depression indicated absence of reduction in vigour in the F2 generations for yield and all other yield attributes. Investigation on pattern of inheritance of kernel colour revealed that kernel colour in rice is a complex qualitative character. Each red and white colour may be separately controlled by two or more sets of genes having both inhibitory and duplicate type of gene interactions with predominance of inhibitory type gene interaction. From 22F2 generations, seven early stabilized promising lines and 26 promising segregants were selected. Two early stabilized lines were found to possess most of the ideotype features proposed by IRRI with preferable cooking quality characters. Their further evaluation and multiplication are being carried out at the Agricultural Research Station, Mannuthy, Kerala Agricultural University. By hybridization, it was possible to successfully transfer the non sticky nature and red kernel colour of Mattatriveni to a high yielding Taiwan variety whose kernel is white and sticky on cooking. The gene action studies revealed that there is ample scope for yield improvement in rice both through pedigree breeding and heterosis breeding. As yield and yield components were found to be under the control of all the three types of gene actions namely, additive, dominance and epistasis, intercrossing of early segregating generations derived from multiple crosses seems to be the best suited method of breeding for yield improvement in rice. Future line of studies suggested 1. Conversion of the already obtained cytoplasmic male sterile F1 crosses to fully sterile CMS lines by repeated back crossing with the respective recurrent parents. 2. Screening from the segregating populations of these cytoplasmic male sterile crosses for 100 per cent cytoplasmic male sterile lines. 3. Confirmation of the restoring ability of the proposed Mattatriveni 'R' line and identification of other restorers. 4. Incorporation of the sterile cytoplasm of Vytilla 3 into other elite genotypes other than IR36 and Hraswa. 5. Screening for cytoplasmic male sterile system in other saline tolerant lines. 6. Screening of promising segregants selected, for high yield and quality with multiple resistance to pest and diseases, for developing varieties suited to various climatic and soil conditions of Kerala.ThesisItem Open Access Genetic analysis of seed dormancy and productivity in groundnut (Arachis hypogaea L.)(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 1997) Tessy Joseph; KAU; Namboodiri, K M NInvestigations on genetic analysis of seed dormancy and productivity in groundnut (Arachis hypogaea L.) were carried out in the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara from 1992-95. The objective of the study was to find out the gene effects of biometric traits and seed dormancy in groundnut, so as to suggest appropriate breeding methodology and parental combinations to evolve domant, high yielding and early manuring varieties. The findings of the study are briefed below. Evaluation of 28 genotypes (14 domant and 14 non domant) for two seasons revealed that wide range of variability existed among them. Donors for specific traits were identified . The genotypes were also genetically diverse and could be grouped into four clusters. The line x tester analysis with three lines and five testers revealed that additive gene effects governed most of the characters except pod yield and number of mature pods , for which , non addictive gene effects were important. To harness both the types of gene effects pedigree method followed by selection in advanced generations will be fruitful.ThesisItem Open Access Identification of stable male sterile lines and better combiners for exploitation of hybrid vigour in rice (Oryza Sativa L.)(Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 1998) Rosamma, C A; KAU; Vijayakumar, N KInvestigations to identify stable male sterile lines and better combiners for the exploitation of hybrid vigour in rice were conducted at College of Horticulture, Vetlantkkara and at Agricultural Research Station, Mannuthy during 1994-98. The study included evaluation of cytoplasmic - genic male sterile (CMS) lines to identify stable lines, identification of maintainers and restorers for different CMS lines, inheritance of fertility restoration, studies on the genetic distance between maintainers and restorers and genetic analysis of the hybrids. Out of the ten CMS lines evaluated, seven were identified as stable for pollen and spikelet sterility behaviour. Studies on the floral traits which influence outcrossing expressed variation between CMS lines and between seasons. Jyothi, Aruna, Pavizham and Ptb 10 produced more number of sterile hybrids when crossed with CMS lines having WA cytoplasm and hence these varieties can be used as maintainers. More number of fertile hybrid combinations were produced by Annapoorna, Matta Triveni, Kanchana, IR 36 and Aiswarya indicating the use of these varieties as restorers for WA cytoplasmic source. All the genotypes under study produced sterile hybrids when crossed with CMS lines having O. perennis cytoplasm and no restorers could be identified for this new source of cytoplasmic male sterility. Inheritance studies on fertility restoration indicated polygenic mode of inheritance for this particular character. Forty four rice genotypes included in the hybrid rice breeding programme were grouped into nine clusters, each having different number of genotypes. Maintainers and restorers were distributed in different clusters and no direct relation could be established between heterosis and genetic distance of the parents. Genetic analysis of the 34 fertile hybrids resulted in the identification of five hybrids having significant positive standard heterosis. Among the male sterile lines IR 68890A was identified as the best combiner for most of the agronomic traits and IR 68890A/Aiswarya was the best specific hybrid combination. Magnitude of the gca variance was more than the variance due to sca for days to flowering, total duration, harvest index, 100 seed weight and other grain characters indicating predominance of additive variance for these characters. Variance due to sca was more for plant height, tillers per plant, total dry matter production, grain yield per plant, straw yield per plant, panicle length and filled grains per panicle indicating predornlnance of variance due to dominance and epistasis. Studies on association of characters in hybrids revealed that total drymatter accumulation, harvest index, number of filled grains per panicle, grain breadth, panicle weight, grain density, flag leaf area and leaf area index at 60 days after sowing were positively correlated with grain yield produced by the hybrids. Negative influence of sterile cytoplasm was identified for most of the agronomic attributes.