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Theses

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1986 - 19874
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Subject: Plant Pathology × End date: 1987 × Start date: 1985 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Study of bacterial leaf spot of betel vine- biochemical changes and control
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1986) Koshi, Abraham; KAU; James, Mathew
    The bacterial leaf spot is one of the most serious diseases of betel vine in Kerala. The bacterium is one of the most serious disease of betal vine. Confidering the seriouness of the disease , studies were undertaken on the different aspects of the disease and to find out a suitable control /management practice.
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    ThesisItemOpen Access
    Strain variation in Rhizoctonia solani Kuhn [Thanatephorus cucumeris (Frank) Donk] causing sheath blight of rice
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1986) Vijayan, M; KAU; Chandrasekharan Nair, N
    Symptoms of sheath blight disease usually develop towards the tillering stage of the rice crop. Discolouration initially appearing on the sheath at or above the water level develop into ellipsoidal lesions. The lesions are light greenish gray in colour with dark brown margin. As the disease progress the lesions coalesce and become oblong to irregular in shape. In severe condition the lesions encircle the culm and cause rotting of the sheath. The disease then spreads to the leaves and such plants are killed. Sclerotia and silvery threads of the fungal mycelium appear on the affected regions under high humid conition. The casual organism was Isolated and identified as Rhizoctonia solani Kuhn. The hyphae branched near the distal septus with a costriction at the branch base. Hyphae were multinucleate and in culture showed brown pigmentation. Nature sclerotia were subglobose with rough regular surface.
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    ThesisItemOpen Access
    Effect of application of plant protection chemicals on the survival of Rhizoctonia solani Kuhn
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1986) Lulu Das; KAU; Chandrasekharan Nair, M
    In Kerala, the incidence of sheath blight of rice is endemic causing great economic loss. The present investigation was undertaken to make a critical assessment of the efficacy of various palnt protection chemicals, viz., fungicides, insecticides and herbicides on the incidence and intensity of sheath blight of rice and on the survival of the pathogen. The organism was isolated from naturally infected rice fields and its pathogenicity proved. Studies on the viability of sclerotia revealed that they sclerotia remained viable upto 210 days in all the different types of soils namely sandy, clayey and loamy. The organism could survive on straw bits upto 180th ady only.
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    ThesisItemOpen Access
    Monographic studies on edible species of pleurotus and standardisation of the techniques for large scale cultivation
    (Department of Plant Pathology, College of Agriculture, Vellayani, 1987) Suharban, M; KAU; Chandrasekharan Nair, M
    Mushrooms have long been recognized as a food because of their nutritive value and flavour and hence are grown on commercial scale on many parts of the world. In recent years cultivation of Pleurotus species are becoming popular in many of the tropical areas. No effort has been made in the past to collect, identify, describe and catalogue the Pleurotus mushroom flora of Kerala and standardise the techniques for their large scale cultivation. The present study was therefore initiated to achieve the above objectives. Collection, identification and description of the Pleurotus flora naturally occurred in and around the College of Agriculture and parts of Trivandrum district were carried out with the help of a data sheet. Twenty species of Pleurotus properly identified were further subjected to detailed study. A key was constituted to enable easy identification of gill the twenty described species. Out of the twenty species described, eight species are new records for India. Among the common cultivable species of Pleurotus. P .sajor-caju was found to be the most suitable mushrooms for the warm humid climatic condition of Kerala. The optimum temperature for maximum growth of this mushroom was found to be between 15 to 50 *C. Comparative efficacy of various containers and substrates used for spawn production revealed that Maize and empty wine bottle were the best substrate and container respectively for spawn production. Trials on cultivation of P. sajor-caiu on logs of common trees revealed Mango tree log to be the best in getting higher yield. Polythene bag was found to be the best container in supporting maximum sporocarp formation. Straw of local varieties of rice were better than high yielding varieties of rice in supporting sporocarp, formation. Comparative efficacy of straw made into bits and small twists with six species of Pleurotus revealed higher yield of 775 g per kg of substrate with spawn of Pleurotus- sajor-caju establishing its superiority for cultivation in Kerala. Cultivation of P .saior-caju in different seasons of the year revealed that this mushroom can be successfully cultivated in Kerala all through the year on paddy straw.