Browsing by Author "APURVA, V"
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ThesisItem Open Access STUDIES ON CASTOR (Ricinus communis L.) WILT CAUSED BY Fusarium oxysporum f. sp. ricini Nanda and Prasad(University of Agricultural Sciences, Bangalore, 2020-10-01) APURVA, V; KARUNA, K.Castor wilt caused by Fusarium oxysporum f. sp. ricini is a potential threat for commercial cultivation of crop. The fungus isolated from roots of wilted castor plants on PDA produced fluffy mycelia with purple pigmentation. Pathogenicity was established by proving Koch’s postulates. Based on pathogenicity and morphological characters the pathogen was identified as F. oxysporum f. sp. ricini by comparing with the original descriptions. Cultural studies revealed that highest growth on different media viz., Sabourauds dextrose agar, carrot agar and Richard’s synthetic agar. But profuse sporulation was in rose Bengal agar, host leaf extract and PDA. The fungus grew well at temperature of 25°C with highest dry mycelial weight of 373.3 mg with abundant sporulation at 25°C and 30°C whereas slightly acidic pH (5-6) favoured good growth and sporulation. Among the fungal bioagents Th14 strain of Trichoderma harzianum exhibited maximum inhibition and Bacillus velezensis (P42) showed highest inhibition among the bacterial bioagents. Among the fungicides tested in vitro, combi products viz., carbendazim + mancozeb, tebuconazole + trifloxystrobin and azoxystrobin + difenoconazole showed complete inhibition at 150, 250, 500 ppm; contact fungicide mancozeb at 1000 ppm; systemic fungicide carbendazim at 150 ppm were found to be superior in inhibiting growth. Out of 39 entries screened under glasshouse condition, six genotypes viz., Konehalli, ICS-252, BCH-43, BCH-89, BCH-95, 48-1 were found highly resistant.ThesisItem Open Access A STUDY OF CARBON SEQUESTRATION POTENTIAL OF ARECANUT BASED CROPPING SYSTEMS OF COASTAL AND HILLY ZONES OF KARNATAKA(University of Agricultural & Horticultural Sciences, Shivamogga, 2017-07-15) APURVA, V; Dr. GANAPATHI; Dr. K.T. GURUMURTHYAn investigation was undertaken at, Department of Soil Science and Agricultural Chemistry, College of Agriculture, UAHS, Shivamogga to know Carbon Sequestration potential of areca nut based cropping systems of coastal and hilly zones of Karnataka.The study area coveredthe soils of Mangaloreand Udupidistrict of coastal (zone-10) and Chikkamagalur, Kodugu and Shivamogga district of hilly (zone-9 ).Representative soil samples were collected from 0-30 cm, 30-90 cm and 60-90 cm depth from areca nut Sole, arecanut + banana, arecanut+cocoa, arecanut+pepper, arecanut+mixed, arecanut+coffee and areca nut +orangefrom 2 location.The results revealed that soil pH were acidic to neutral with normal EC and Sandy loam to sandy clay loamin texture. TheSOC contents were medium to high ranged and decreases with depth. Among the cropping systems studied, arecanut+mixed recorded higher mean potassium permanganate oxidizable organic carbon(1387.33mg kg-1), cold water extractable carbon (409.06mg kg-1), total carbon (29.39g kg-1), total organic carbon (18.70g kg-1),total inorganic carbon (0.2136g kg-1) andsoil microbial biomass carbon (370.33mg kg-1) fractionsas compared to other cropping systems and decreases with lower depth. Among different areca nut based cropping system E4/E6 values were higher in areca nut +mixed (1.166).Carbon fractions were higher in 0-30cm soil depth and decreases in lower depth of areca nut based cropping systems. Humic acid was higher in areca nut +mixed (5.35) and fulvic acid was higher in arecanut+ coffee (5.01).Correlation study showed that the various carbon fractions were positively and significantly correlated amongst themselves and with pH, clay and CaCO3 (%) content of the soils.