Browsing by Author "Kumari"
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ThesisItem Open Access Role of nematodes in soil health sustenance: relating their assemblages to soil types and cropping systems(UAS Dharwad, 2013) Kumari; S. LingarajuNematodes are functionally diverse. Most research on them is focused on plantparasitic nematodes that attack the roots of cultivated crops. Less attention has been given to nematodes that are not plant-feeders and play beneficial roles in soil environment. Therefore, the present study was taken up with the objective of determining nematode assemblages in different soil types and cropping patterns. Two agro-ecological Zones of Karnataka were selected (Zone III and IX), soil were vertisols and alfisols. The dominant cropping patterns were cotton, onion+chilli, paddy-paddy-paddy and paddy-paddy-paddy respectively. In addition to this, a field trial was taken was taken up at MARS, UAS Dharwad in two consecutive seasons, viz. Rabi-2011 and Kharif-2012 with major cropping pattern of this area (chickpea and soybean respectively) to know the influence of fertilizers and manures (singly and in combinations) on nematode assemblages. Also influence of soil physical and chemical properties were studied during the course of present investigation employing the soil samples which were collected during surveys and during field experimentation. Differences in nematode assemblages were observed during the study in different soil types with respect to trophic groups across different agro-ecological zones and during field study. MWC had positive correlation with nematode assemblages. BD on total nematode abundance was negative and showed significant positive correlation. Whereas pH showed negative correlation and effect of EC was almost negligible. Under field study, both FYM and vermicompost singly and in combination increased the numbers of bacterivores and fungivore nematodes and lowered that of plant parasitic nematodes. Different indices viz., NCR, NGR, H’, combined maturity index (MI) were calculated - a slight change across the sampling period was noticed. Results suggested that a bacterial decomposer pathway dominated, mediated by bacterivorous nematodes. In a microcosm experiment it was observed that there was increase in total available nitrogen from 12 to 14 (kg/ha) over control in presence of bacterivorous nematodes.ThesisItem Open Access Role of nematodes in soil health sustenance: relating their assemblages to soil types and cropping systems(UASD) Kumari; S. LingarajuNematodes are functionally diverse. Most research on them is focused on plantparasitic nematodes that attack the roots of cultivated crops. Less attention has been given to nematodes that are not plant-feeders and play beneficial roles in soil environment. Therefore, the present study was taken up with the objective of determining nematode assemblages in different soil types and cropping patterns. Two agro-ecological Zones of Karnataka were selected (Zone III and IX), soil were vertisols and alfisols. The dominant cropping patterns were cotton, onion+chilli, paddy-paddy-paddy and paddy-paddy-paddy respectively. In addition to this, a field trial was taken was taken up at MARS, UAS Dharwad in two consecutive seasons, viz. Rabi-2011 and Kharif-2012 with major cropping pattern of this area (chickpea and soybean respectively) to know the influence of fertilizers and manures (singly and in combinations) on nematode assemblages. Also influence of soil physical and chemical properties were studied during the course of present investigation employing the soil samples which were collected during surveys and during field experimentation. Differences in nematode assemblages were observed during the study in different soil types with respect to trophic groups across different agro-ecological zones and during field study. MWC had positive correlation with nematode assemblages. BD on total nematode abundance was negative and showed significant positive correlation. Whereas pH showed negative correlation and effect of EC was almost negligible. Under field study, both FYM and vermicompost singly and in combination increased the numbers of bacterivores and fungivore nematodes and lowered that of plant parasitic nematodes. Different indices viz., NCR, NGR, H’, combined maturity index (MI) were calculated - a slight change across the sampling period was noticed. Results suggested that a bacterial decomposer pathway dominated, mediated by bacterivorous nematodes. In a microcosm experiment it was observed that there was increase in total available nitrogen from 12 to 14 (kg/ha) over control in presence of bacterivorous nematodes.ThesisItem Open Access Studies on molecular variations in Phaeoisoropsis personata (Berk and M.A. Curtis) van Arx. Causing late leaf spot of groundnut (Arachis hypogea L.)(2008) Kumari; S.S.AdiverThe present investigation on molecular variability in Phaseoisariopsis personata was carried out during the period 2006-08 at the Department of Plant Pathology, College of Agriculture, University of Agricultural Sciences, Dharwad. The study includes molecular variability in P. personata through isozyme and RAPD technique. Pathogenic isolates of P. personata were obtained from 15 commonly grown groundnut cultivars (resistant and susceptible genotypes) in MARS, UAS Dharwad and also collected in nine locations of Karnataka (Arabhavi, Annigere, Bijapur, Indalgi, Hammanamatti, Shirahatti, Nippani, Raichur and Dharwad) for investigation on molecular variability. Based on isozyme analysis of four enzymes (peroxidase, Polyphenol oxidase, catalase and super-oxide-dismutase) two major clusters were obtained which revealed little variation in their protein makeup. Based on isozyme bands it was possible to categorize the isolates into different groups. From the investigation it is clear that the isolates V14 (LSVT-1-2006-2) and HAN (Hanumanamatti) exhibited more peroxidase activity followed by isolates V15 (TAG-24) and IND (Indalgi) from Dharwad and other locations respectively by expressing more number of bands. Based on RAPD data distinguished the fifteen isolates from Dharwad and eight isolates from other locations into two major clusters, A and B each. Among the isolates from Dharwad location, isolates V12 (ICGV-86950) and V13 (LSVT-I-2005-7) had maximum similarity, whereas isolates V8 (JL-24) and V1 (DH-212) showed least similarity. Among the isolates obtained from different locations; isolates from Annigere and Bijapur had maximum similarity whereas isolates from Raichur and Arabhavi showed least similarity. So the results obtained from the cluster analysis revealed that sub-cluster groups composed of isolates belonging to same geographical locations with certain variability. The present investigation revealed a great molecular variation existing among the isolates of P. personata which could be used to distinguish variation among the isolates of P. personata. The study also brought out that, the pathogen showed molecular variation over locations and also in a location depending on the genotypes grown there.