PG Thesis

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Subject: search.filters.subject.Oryza Sativa

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    Genetic analysis in F2 And F3 progenies of selected crosses of rice varieties of diverse origin
    (Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, 2000) Faseela, K V; Rajan, S
    The research project 'Genetic Analysis in F2 and F3 Progenies of Selected Crosses of Rice Varieties of Diverse Origin' was carried out in the College of Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur durinq the period January to December, 1998. The major objectives of the study were to understand the various genetic parameters of characters under study, identification of yi&ld components and formulation of selection model so as to isolate promising lines having desirable ideotypic features • from the segregating generations. The high yielding varieties developed from such lines will have a broad genetic base as the parents of selected crosses are of diverse origin. Components of heritable variation revealed that the characters showed decreased trend of variability from F2 to F3. PCV was higher than GCV in both generations for all the characters studied. Low PCV and GCV were observed for grain length, panicle length and duration to 50% flowering in both generations, while grain density showed low PCV and GCV in F3 only. In general, broad sense heritability estimates were observed to be higher in F2 than F3. The characters, plant height at harvest, total tillers plant", LIB ratio, 1000 grain weight, secondary branches panicle' and tertiary branches panicle:' provided great help in direct selection from phenotypic performance, as they exhibited higher values of genotypic coefficient of variation, heritability and expected genetic advance. The .. character, grain length showed little scope of improvement through selection due to low GCV and GA . • Correlation studies in F2 and F3 revealed that positive correlation existed between yield and component characters, namely, total tillers, panicle bearing tillers and tertiary branches panicle". Negative correlation was observed for 1000 grain weight with yield in both the generations. Panicle length and duration to 50% flowering exhibited absence of association with yield in F2 and F3, which indicate that these traits can be recombined as desired. In F3, LIB ratio and grain length exhibited positive correlation and grain breadth exhibited negative correlation, with yield, while these characters showed absence of association with yield in F2• Plant height and number of grains panicle:' exhibited negative association with yield in F2 where as number of grains panic!e' exerted positive association with yield in F3 and plant height showed absence of association with yield in F3. Genotypic correlation among di~ferent yield components in F2 and F3 revealed that semidwarf plants with higher number of productive tillers produced grains with higher LIB ratio and lesser grain weight, which in turn increased the yield. The study also showed that, when number of grains and compactness of• panicles increase, grains become more slender with reduced grain weight. Study of path coefficient analysis revealed that all the characters influenced the yield directly or indirectlv through some other traits. The correlation and path analysis study suggested that during selection, breeder should give emphasis on" semidwarf olant stature, higher number of productive tillers, compact panicles, reduced number of secondary branches, high LIB ratio of grains with reduced density and weight. A selection model was formulated consisting of the characters, , namely, yield ha:'. total tillers plant". LIB ratio, grain breadth and grain density. Using this model, ranking of 105 genotypes in F3 was done and identified that the accessions, V 82 and V 89' belonging to lA 36 x Mattathriveni, were the best genotypes. Study revealed that all the four crosses namely, Vytilla 3 x Mattathriveni, Vytilla 3 x Kaohsiung Sen Vu 338, Mattathriveni x Mahsuri and lA 36 x Mattathriveni, were promising enough to derive superior segregants, the best among them being IR 36 x Mattathriveni. The plants with red kernel, identified in F3 of the cross IR 36 x Mattathriveni, can be used for the development of high yielding varieties with red kernel and preferable cooking qualities suited to Keralites, as well as resistance to biotic and abiotic stresses. This investigation also suggested that crosses from parents of diverse origin will broaden the genetic base of the varieties to be developed in future and will help to break the yield plateau in rice.
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    Response of seed priming nutrient management and irrigation on upland rice
    (Department of Agronomy, College of Agriculture, 2000) Usha Thomas, C; Kuruvilla, Varughese
    A field experiment was conducted at the Instructional Farm attached to the College of Agriculture, Vellayani during the late first crop season of 1999 to study the effect of nutrient management and seed priming on upland rice under varying levels of irrigation. The experiment was laid out ill split split plot design with three replications. The treatments included three levels of irrigation (IW /CPE ratio of 1.5, 1.0 and no irrigation) in the main plots, three levels of NPK (20 : 10 : 15, 40 : 20 : 30 and 60 : 30 : 45 kg ha-I) in the sub plots and two levels of seed priming (1 per cent KCI and 2.5 per cent KCl immersed for 15 hours) in the sub sub plots. Results of the experiment revealed that effect of both irrigation and nutrients and their combinations had significant influence on most of the biometric and yield attributing characters of upland rice. Irrigation at an IW/CPE ratio of 1.5 and fertilizer dose 'of 60 : 30 : 45 kg ha" NPK were found significantly superior to lower levels. Eventhough, the effect of seed priming was significant on almost all the growth characters, the effect was not visible on the yield attributing characters and yield of the crop. Irrigation and fertilizer treatments exerted a remarkable influence on the proline content of leaves and grain protein content while irrigation alone exerted significant influence on RL WC and partitioning of biomass. The uptake of nutrients was profoundly influenced by the treatments. N and P uptake was influenced by irrigation and NPK levels whereas that of K was influenced by nutrient and seed priming levels. . The root morphology was substantially altered by irrigation treatments and I I recorded the highest value for all the characters studied. Though WUE was highest at the no irrigation treatment (13) it was very inferior and uneconomic III grain and straw yields. Hence, h level of irrigation is considered as the best treatment for attaining higher WUE. Among the fertilizer levels, F 3 (60 : 30 : 45 kg ha-I NPK) registered the highest WUE. Impact of seed priming also was significant and S I recorded the highest WUE. The results of economic analysis revealed that BC ratio was maximum when the irrigation was scheduled at an IW /CPE ratio of 1.5. The nutrient dose at F3 (60 : 30 : 45 kg NPK ha-I) and seed priming at SI (1 per cent KCI) was also found to be profitable.
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    Genetic diversity analysis of indigenous rice varieties in Kerala using molecular markers
    (Department of Plant Pathology, College of Agriculture, Vellayani, 2019) Ajith, M K; Jayalekshmy, V G
    The present study entitled “Genetic diversity analysis of indigenous rice varieties in Kerala using molecular markers “was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, Thiruvananthapuram during 2017-2018. The study was conducted with the objective to analyze the genetic diversity of traditional rice varieties in four agro climatic zones of Kerala using RAPD and SSR markers. Five varieties were collected from the each agro climatic zones viz., hill areas of Wayanad, rice growing tract of Palakkad, saline soils of Pokkali and Kuttanad soils. The DNA was isolated and RAPD analysis with 10 Operon primers and SSR analysis was done with ten RM primers. In the RAPD analysis the ten operon primers produced 88 amplicons with an average polymorphism 82%. Resolving power OPC-07 (15.4) had the highest value but its Polymorphism Information Content and Effective Multiplication Ratio (EMR) were considerably low. Considering all the three parameters together primer OPF-06 is found to be the best RAPD primer with considerably high polymorphism information content, resolving power and effective multiplication ratio. The dendrogram constructed based on the RAPD scoring showed that varieties Pokkali and VTL-2 had maximum similarity. These two were from Pokkali rice tract. PTB 12 from Pattambi was found to be unique and it clustered with others only at 30% similarity.The clustering of the genotypes did not show any correlation with the geographic origin. ABL 12 and VTL- 2 showed 70 % similarity but those two were from Wayanad Hills and Pokkali tract respectively. Vellakuttadan from Moncombu clustered with PTB 2 from pattambi at 72% a similarity. Kochuvith and Vellakuttadan from Moncombu clustered at 67 %. All the SSR markers produced two alleles except RM 210 and RM 204 which produced four alleles and one allele respectively. All the alleles of all the markers were polymorphic except that of primer RM204. The polymorphism information content of the SSR primers used in the study ranged from 0 to 0.88. In this study the highest PIC value of 0.88 was reported by RM 210 followed by RM 567 (0.85). The resolving power and EMR was also highest for RM 210. The dendrogram constructed based on the SSR markers could give a clustering of genotypes more correlated with the geographic origin. Genotypes Kochuvithu and Vellakuttadan showed 100 % similarity both where from Kuttanad. But Karavalakochuvith, T.virippu, and PTB 2 also showed 100% similarity but these three were from Moncompu, Pokkali and Palakkad respectively. At around 90 % similarity AMB 14, AMB 22 from Wayanad, Pokkali andVTL-2 from Pokkali, PTB 13 and PTB 8 from Palakkad clustered showing more correlation to the Geographic origin. SSR markers being sequence specific and flanking the repeat sequence which has more role in evolution, are more reliable in predicting the Genetic diversity based on origin. Since both of them could not give a clear-cut clustering based on geographic origin an analysis using both the markers together was done. This gave a better picture of the clustering as it involved more number of variables. But here also the varieties from Wayanad A1 to A5 were scattered in different clusters. Only A 14 and A15 (AMB 14 and AMB 5) clustered at 60 percentage similarity. The accessions from moncompu (A6-A10) clustered at around 50 % similarity. In the accession from Pokkali tract (A11-A15) only T.virippu to VTL-2 clustered at 78 % similarity. Accession from central zone Pattambi (A16-A20) was scattered into different clusters. PTB 12 was unique from other accessions. This molecular diversity analysis of the traditional rice genotypes from four different agro climatic zones could find that the maximum similarity was 78% and that too only between two accessions. The diversity among the genotypes was 64% as all the genotypes clustered at 36% similarity. The clustering of the genotypes did not show any correlation with the geographic origin. Exchange of varieties between the farmers and some amount of natural crossing would have led to the mixture of populations of rice genotypes in different agro climatic zones.
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    Agronomic biofortification of zinc in rice (oryza sativa L.)
    (Department of Agronomy,College of Agriculture, Vellayani, 2019) Amal Jose; Jacob, D
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    Molecular characterization of shattering in weedy rice (Oryza sative f. spontanea) biotypes of kerala
    (Department of Plant Biotechnology, College of Agriculture, Vellayani, 2017) Shelvy, S; Ameena, M
    The study entitled “Molecular characterization of shattering in weedy rice (Oryza sativa f. spontanea) biotypes of Kerala” was conducted at the Integrated Biotechnology Block, College of Agriculture, Vellayani, Thiruvananthapuram during 2015-2017. The objective of the study was isolation and sequencing of genes related to shattering viz. sh4 and qsh1 in weedy rice biotypes and characterization by expression profiling and phylogenetic analysis. Degenerate primers were designed for sh4 and qsh1 genes based on the gene sequences retrieved from NCBI database (sh4 and qsh1 forward and reverse primers) which were used to isolate and identify the genes. Both genomic DNA and Total RNA of weedy rice and cultivated rice Uma were isolated. PCR was done using both genomic DNA and cDNA. Amplification was obtained in two sets of designed primers i.e. sh4 (FW2 x RW2) and qsh1 (FW2 x RW2). When DNA was used as template for PCR, two of the sh4 primers and one of the qsh1 primers designed for shattering yielded amplicons at the expected size of 649bp, 696bp and 747bp respectively. PCR in cDNA samples of RNA amplicon of size ~690bp with the primer combination of sh4 (FW2 x RW2) in flag leaf was observed. Also, an amplicon of size ~750bp in flag leaf cDNA was produced using degenerate qsh1 FW2 x RW2 primers. None of these primers produced an amplification in any of the cDNA samples of cultivated rice Uma. The tBLASTx programme showed that the amplicon of size ~690bp was similar to shattering 4 (sh4) genes of Oryza populations, whereas the amplicon of size ~750bp belonged to qsh1 gene for putative transcription factor qsh1 of rice populations and mRNA of Oryza sativa japonica group. The result clearly revealed that the gene responsible for shattering viz., sh4 and qsh1 are present in both weedy rice and cultivated variety Uma as evidenced from the PCR amplification of genomic DNA. However, the genes responsible for shattering investigated in the present study viz., sh4 and qsh1 were not expressed in any of the growth stages in cultivated rice variety Uma. The NCBI conserved Domain Search programme, showed that the qsh1 FW2 x RW2 sequence of amplicon at ~750bp (obtained by reaction using weedy rice flag leaf cDNA) belonged to homeobox kn domain. The sequence of the amplicons of qsh1 obtained was the partial fragments of the first ever qsh1 gene for putative transcription factor qsh1 to be isolated from Oryza sativa f. spontanea. Phylogenetic tree constructed for sh4 FW2 x RW2 sequence, had highest similarity to shattering (sh4) gene of Oryza meridionalis voucher and also had relationship with Oryza rufipogon and Oryza sativa. However, the weedy rice qsh1 FW2 x RW2 query sequence was closely related to qsh1 gene of Oryza rufipogon, together with Oryza sativa indica group and Oryza sativa japonica group. Semi quantitative analysis with sh4 and qsh1 gene primers showed that the sh4 gene was expressed in flag leaf and grains and qsh1 gene was expressed only in the flag leaf. From this study it can be inferred that the gens responsible for shattering in weedy rice biotypes of Kerala viz. sh4 and qsh1 are present both in cultivated rice and weedy rice. However, the genes are expressed only in weedy rice during the flowering stage.