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2011 - 20152
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Subject: Agricultural Biotechnology × Author: KAU × End date: 2015 ×
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    ThesisItemOpen Access
    Molecular marker development for cassava mosaic disease resistance using bioinformatics tools
    (Department of Plant Biotechnology, College of Agriculture, Vellayani, 2015) Ambu, Vijayan; KAU; Sreekumar, J
    The study entitled “Molecular marker development for cassava mosaic disease resistance using bioinformatics tools” was conducted at ICAR-CTCRI, Sreekariyam, Thiruvananthapuram during October 2104 to October 2015. The objectives of the study included development and evaluation of various SNP and SSR prediction pipelines, computational prediction and characterization of SNP and SSR in cassava, verification of SNP and SSR markers for cassava mosaic disease (CMD) resistant and susceptible breeding lines. The preliminary data set for the identification of SSR and SNP markers was obtained from the EST section of NCBI and the cassava transcript sequences from the Phytozome. A total of 120461 sequences was classified into 20 cultivars. The dataset was reduced to 14336 sequences after several pre-processing and screening steps. The resulting sequences were assembled and aligned using CAP3 and 2088 contigs were obtained. SNPs and SSRs were predicted from these datasets using respective prediction tools. The SNP prediction tools such as QualitySNP and AutoSNP were compared for their performance. Analysis was performed to identify the tool with the ability to annotate and identify more viable nonsynonymous and synonymous SNPs. The SSR prediction tools such as MISA and SSRIT was compared for their performance. Analysis was performed to identify the tool having the ability to predict more viable SSRs and the ability to classify them as mono, di, tri, tetra, penta, hexa and poly SSRs. Using QualitySNP, thirty nonsynonymous SNPs and twenty-six synonymous SNPs were identified. Using MISA, n 217 mono SSRs, 132 di SSRs, 139 tri SSRs, 3 tetra SSRs, 1 penta SSRs, 3 hexa SSRs and 42 complex SSRs were identified. Five sequences from identified SNPs and SSRs which have high hit percentage were selected for validation and primer designing for CMD resistant genes. These primers were validated using 5 resistant and 5 susceptible cassava varieties. Among the 10 primers after validation in wet lab, one SNP (SNP896) and one SSR (SSR 2063) primer was able to clearly differentiate between the resistant and susceptible varieties which can be used as potential markers in the breeding program for screening CMD resistance in cassava.
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    ThesisItemOpen Access
    Production technology for organic watermelon
    (College of Agriculture, Vellayani, 2011) Sheeba, B S; KAU; Sajitha, Rani T
    The present investigation was carried out at College of Agriculture, Vellayani to find out a suitable date of planting and the effect of different doses of FYM on the growth, yield and economics of organic watermelon from October 2010 to March 2011. The experiment was laid out in Split plot design with four replications. The Main plot treatments consisted of five dates of planting (D1- October 15th, D2- November 1st, D3- November 15th , D4- December 1st and D5- December 15th. The sub plot treatment consisted of four levels of nutrients viz. (T1-5 kg FYM plant-1, T2-4 kg FYM plant-1, T3-3 kg FYM plant-1 and T4-2 kg FYM plant-1 + 7:2.5:2.5 g NPK plant-1 [control] - POP Recommended dose of KAU). Plants sown on earlier planting date recorded significantly more number of branches, maximum vine length, female flowers plant-1, total fruit plant-1, total fruit ha-1, marketable fruit plant-1, marketable fruit ha-1, marketable yield ha-1, average fruit weight, fruit diameter, flesh thickness and fruit girth compared to the later planting dates. Flower opening was significantly influenced by planting dates. The earlier planting took maximum days to first harvest and maximum crop duration compared to later planting dates. Quality attributes like total sugar and non-reducing sugar were significantly higher for earlier planting dates. Uptake of N and K was more in earlier planting dates compared to that of later planting dates. Gross return, Net return and B: C ratio of water melon were recorded higher for earlier planting dates. The highest level of nutrient (5 kg FYM plant -1) recorded maximum days to first harvest and took more crop duration. Maximum number of branches plant-1, maximum vine length , total fruit plant-1, marketable fruit ha-1, marketable yield ha-1, average fruit weight, fruit length, fruit diameter, flesh thickness and fruit girth was also recorded by the highest level of nutrient ( 5 kg FYM plant -1) compared to the lower levels of nutrients. Uptake of N, P and K was also significantly more in plots receiving highest level of nutrient. The available N, P and K content in soil was also significantly more in plots receiving highest level of nutrient. The highest Gross return, Net return, B: C ratios for watermelon were also recorded by the highest level of nutrient (5 kg FYM plant -1).