1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Phenotypic and molecular characterisation of phytophthora sp. inciting leaf fall of nutmeg(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2015) Sumbula, V; Sally K MathewItem Identification of the donors for blast resistance from traditional rice varieties of Kerala using functional markers(Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, 2014) Henry Nickolas; Jayalekshmy, V GThe research project entitled “Identification of the donors for blast resistance from traditional rice varieties of Kerala using functional markers” was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani, Thiruvananthapuram and farmer’s field at Pattambi, Palakkad district during 2012 - 2014. The major objectives of the study were to identify the traditional rice varieties with blast resistance genes (Pi 1, Pi 2, Pi kh) using associated functional markers and the field scoring of the lines under disease stress condition. In the present study, thirty traditional rice varieties of Kerala were taken for resistance gene source identification and field level evaluation. The selected rice varieties were screened for the presence of the reported blast resistance genes Pi 1, Pi 2 and Pi kh using three SSR (Simple Sequence Repeat) markers RM224, RM527 and RM206 respectively. C101Lac (Pi 1), C101A51 (Pi 2) and Tetep (Pi kh) from DRR, Hyderabad were taken as the resistant gene source check. Functional marker analysis showed the presence of gene Pi 1 in nine varieties. Twenty varieties showed the presence of gene Pi 2 and six varieties showed the presence of gene Pi kh. Among these, three varieties were having a gene combination of Pi 1 and Pi 2. Three varieties were having genes Pi 2 and Pi kh and two varieties had Pi 1 and Pi kh gene combination. Five varieties did not show the presence of molecular marker linked to any of the genes under study. Field screening was done for scoring the varieties for blast disease resistance by growing in the disease prone farmer’s field at Pattambi. From screening, ten varieties were found to be moderately resistant and fifteen varieties displayed moderately susceptible response. Analysis of variance of the infection index calculated from disease score showed that, nine varieties were having low index and they were on par. All the remaining varieties showed susceptible response. None of the varieties were immune or resistant. Popular rice varieties Uma and Jyothi showed a high infection index. Comparing the disease score and the presence of genes, it was inferred that, genes Pi 1 and Pi kh in combination, imparted moderate resistance under Kerala condition. Varieties Parambuvattan and Kavunginpoothala having these two genes showed low infection index in the field screening. Considering single gene effect, gene Pi 1 imparted moderate resistance. Varieties Thekkan chitteni and Njavara from Kunnathoor are having this gene showed a low infection index. Pyramiding of genes Pi 1 and Pi kh can impart durable resistance to rice varieties of Kerala. Parambuvattan and Kavunginpoothala having these two genes in combination can be used as donors for the genes.Item Molecular characterization of Envinia species causing rhizome rot in banana(Centre for Plant Biotechnology and Molecular Biology, College of Horticulture, Vellanikara, 2017) Geethu Gokul,G; Vimi LouisItem Phenotypic and pathogenic variability of sclerotium rolfsii sacc. infecting fruit crops and ornamentals(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2011) Hajara, P H; Beena, SItem Growth enhancement and management of Phytophthora - Rot in Vanilla Nurseries using microbial inoculants(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2007) Shahida, K; Surendra Gopal, KA study on “Growth enhancement and management of Phytophthora rot in vanilla nurseries using microbial inoculants” was carried out in the Department of Plant Pathology, College of Horticulture, Vellanikkara. The salient findings are abstracted below: The study revealed that Phytophthora meadii Mc. Rac.was the pathogen causing Phytophthora rot in vanilla nurseries. Even though, the treatments did not influence growth characters significantly, AMF (Perumbavoor) and Azospirillum (Mazhuvannur) were the most effective AMF and Azospirillum isolates for enhancement of growth and nutrient content in vanilla. In vitro screening of antagonists against P. meadii revealed that Trichoderma (Vellanikkara) and rhizobacteria ( Mazhuvannur) were very effective against the pathogen. The effective microbial isolates obtained were identified. Among the fungicides tested, Bordeaux mixture, copper hydroxide and copper oxychloride (at all concentrations) and potassium phosphonate (at higher concentrations) completely inhibited the growth of the pathogen. Compatibility studies revealed that potassium phosphonate was compatible with antagonists, while copper fungicides were not compatible with antagonists. Results on compatibility between Trichoderma and antagonistic bacteria showed that Trichoderma was compatible with antagonistic rhizobacteria as well as Azospirillum. The experiment on growth enhancement and Phytophthora rot management in vanilla revealed that all the microbial isolates gave early sprouting. Azospirillum (MVR) gave maximum length. AMF (PBR) and P. fluorescens (commercial) were found to be effective against Phytophthora rot in artificially inoculated vanilla cuttings. Among chemicals tested, potassium phosphonate gave best control against Phytophthora rot.