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M. Sc. Dissertations

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2011 - 20123
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Subject: Nematology × End date: 2012 × Start date: 2010 × Type: Thesis × Thesis Type: M.Sc ×
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Now showing 1 - 3 of 3
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    ThesisItemOpen Access
    Studies on gnotobiology, and effect of sowing dates and varieties of wheat on reproduction of root lesion nematode (Pratylenchus thornei Sher and Allen)
    (CCSHAU, 2011) K Kranti K V V S; Kanwar, R. S.
    Investigations were carried out on in vitro culturing of Pratylenchus thornei, and effect of sowing dates and wheat varieties on reproduction of this nematode. In gnotobiology study, carrot discs on 1% water agar and alfalfa callus on MS medium with 4 mg 2, 4-D were compared for culturing P. thornei, by inoculating 40 surface sterilized nematodes per flask. For callus production, 5-day-old seedlings grown aseptically from alfalfa seed sterilized in conc. sulphuric acid for 15-20 min were used. Carrot disc proved better than alfalfa callus technique in having higher nematode multiplication rate (18.01 in carrot disc, 13.25 in alfalfa callus). In date of sowing experiment, December 5 sowing resulted in maximum final nematode population (394) with reproduction factor 1.9. Reproduction factor was 1.0 and 0.6 in November 15 and October 30 sowings, respectively. The nematode reproduction rate increased with the delay in sowing from October 30 to December 5. Of the 20 wheat varieties/lines evaluated for resistance and tolerance, nine varieties/ lines namely AUS 15854, PBW 343, PBW 550, Raj MR1, Raj 3765, Turkey line (CROC 1/AE. SQUARROSA (224)//OPATA), WH 542, WH 896 and WHD 943 were rated as resistant (Rf <1) whereas 11 varieties viz., C 306, DBW 16, DBW 17, PBW 373, UP 2425, WH 147, WH 711, WH 912, WH 1021,WH 1025 and WH 1080 were rated as susceptible (Rf ≥ 1). Varieties PBW 550, UP 2425, Raj 3765, WH 147, WH 912, WHD 943 and WH 1025 were found tolerant and remaining varieties (AUS 15854, C 306, DBW 16, DBW 17, PBW 343, PBW 373, Raj MR1, Turkey line, WH 542, WH 711, WH 896, WH 1021 and WH 1080) were found intolerant. Bread wheat varieties PBW 550 and Raj 3765 and durum variety WHD 943 proved resistant as well tolerant to this nematode.
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    ThesisItemOpen Access
    Effect of some biotic and abiotic factors on the endospore adherence and development of bacterial parasite, Pasteuria penetrans on meloidogyne javanica
    (CCSHAU, 2011) Jasbit Singh; Walia, R. K.
    Influence of plant root exudates, and culture filtrates (CFs) of rhizobacteria and fungi on the attachment of Pasteuria penetrans endospores to J2 of Meloidogyne javanica was studied in lab experiments. Soil leachate did not affect the endospore attachment. Endospore attachment increased significantly with time. Brinjal, tomato, chickpea and onion root exudates enhanced endospore attachment. Garden bean root exudates promoted the growth and multiplication of protozoans that decreased the number of leftover endospores drastically. CFs of Azotobacter chroococcum, Gluconoacetobacter diazotrophicus and Providentia rettgeri promoted, while that of Enterobacter cloacae reduced the endospore attachment to J2 of M. javanica. The CFs (autoclaved or not) of soil fungi adversely affected the endospore attachment to nematode juveniles. Studies on attempted in vitro culture of P. penetrans in CFs of rhizobacteria revealed the growth of P. penetrans-like stages (tetrads, diads etc.) only in case of A. chroococcum, E. cloacae and G. diazotrophicus. In a screen-house experiment to study the development of P. penetrans during rabi season, it was observed that the life cycle of host nematode M. javanica was prolonged; although eggs were formed in the genital tracts of females but no egg masses were formed till the end of March. The sporogenesis phase of P. penetrans did not occur in any of the five sets inoculated on different dates. P. penetrans development was restricted to vegetative phase only (microcolonies and thallus stages). The nematode development continued albeit slowly; while that of bacterium failed to synchronize with that of nematode.
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    ThesisItemOpen Access
    Studies on bacterial parasite, pasteuria penetrans (Ex thorne) sayre & starr on root-knot nematode, meloidogyne javanica (Treub) chitwood
    (CCSHAU, 2012) Matcha, Udaya Kumar; Walia, R.K.
    Influence of root exudates (REs) and cell free plant root extracts (CFPREs) of brinjal, cowpea, cluster bean, garden bean, okra and tomato was tested on the germination of Pasteuria penetrans endospores. REs and CFPRE of all the plant species did not induce the germination of P. penetrans endospore. In garden bean CFPRE, cauliflower-like colonies similar to P. penetrans were observed in endospore suspension treated with alcohol. In all the treatments rod-shaped lumps of bacteria were evident; they may be contaminants because intact endospores of P. penetrans were also present. Based on a laboratory bioassay, a statistical model was developed for the estimation of P. penetrans endospores in field soils. The regression equation y= 0.045x + 3.779 with R2 = 0.89 was calculated for M. javanica. In a green-house experiment, the role of P. penetrans in the suppression of M. javanica was estimated in naturally infested field soil. Field soil was steam sterilised or treated with formalin/fungicides. Formalin and Bavistin proved to be phytotoxic. P. penetrans alone infected 87.5% nematode females and reduced egg production by ca. ten times. Native fungal and bacteria promoted attachment of P. penetrans endospores but inhibited parasitisation of nematode females by P. penetrans in untreated soil. The development of P. penetrans under open-field and poly-house (ordinary and hi-tech) conditions was studied in winter season. Poly-houses (both ordinary and hi-tech) enabled raising the maximum temperature by 10-12 °C during day time, but there were negligible differences in the minimum temperatures. M. javanica completed it life cycle (females with egg sacs) in 60 days in hi-tech, 70 days in ordinary poly-house and 80 days in open-field conditions. P. penetrans development could not keep pace with that of nematode and it stopped at thallus stage. No mature endospores were found. P. penetrans failed to curtail the reproduction of M. javanica even in hi-tech poly-house, although infection did take place.