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M. Sc. Dissertations
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ThesisItem Open Access Development of bacterial adjuvants for foliar zinc spray in wheat (Triticum aestivum)(2016) Jangra, Raman; Rakesh KumarKeeping in view, importance of zinc for various crops and role of phyllospheric bacteria in making it available to the plants, a total of forty eight bacterial isolates were obtained from five different crops (wheat, mustard, cotton, pearl millet and moong). All the bacterial isolates were characterized for ammonia excretion, IAA production, zinc and Phosphate solubilization. Out of 48 isolates, 32 isolates solubilized zinc oxide in which Isolate MNN1 showed highest Zn solubilization index (37.05). A total of 42 isolates were producing IAA and highest IAA production was observed in isolate MNJ1 (28.173 μg/ml). Ammonia excretion was detected in 42 isolates and highest ammonia excretion was showed by isolate COJ1 (4.890 μg/ml). A total of 29 isolates showed phosphate solubilization and highest P-solubilization index was observed in PMN1 (18.78). On the basis of plant growth promoting traits, total 6 isolates (COJ1, PMN1, MNN1, MNN2, WHN3 and MNJ1) were selected for the pot house studies in wheat. Different yield attributing traits such as chlorophyll content, total leaf soluble protein, dehydrogenase activities, acid and alkaline phosphatases activities, total phyllospheric and rhizospheric bacterial population, plant height and root and shoot weight (fresh and dry) were observed at different interval of time. Maximum chlorophyll content (7.65 mg/g fresh weight), leaf soluble protein (13.33 mg/g fresh weight), soil dehydrogenase activity (209.00 μg TPF/g soil/h), alkaline phosphatase activity (226.07 μg PNP released/g soil/h) was observed in plant treated with foliar application of Zn and isolate COJ1 along with RDF i.e. treatment T11 at 90 DAS. Maximum soil acid phosphatase activity was observed in RDF and Zn foliar application i.e. treatment T3 (178.86 μg PNP released/g soil/h). Total phyllospheric & rhizospheric viable count was observed maximum in foliar application of Zn and isolate COJ1 along with RDF i.e. treatment T11 (7.00 log no. cfu/g leaves & 8.66 log no. cfu/g soil respectively) after 90 days of sowing. Maximum plant height (cm) was observed with foliar application of Zn and isolate COJ1 along with RDF i.e. treatment T11 (24.11 cm). Highest root weight (fresh & dry) were observed in foliar application of isolate MNN2 along with RDF i.e. treatment T9 which were 12.40 g and 4.00 g respectively. Highest shoot weight (fresh & dry) were observed in foliar application of Zn and isolate COJ1 along with RDF i.e. treatment T11 (61 g and 19.8 g respectively). Among the six bacterial isolates (COJ1, PMN1, MNN1, MNN2, WHN3 and MNJ1) tested for plant growth promotion effect in wheat crop, maximum plant growth promotion effect was observed with bacterial isolate COJ1 along with zinc spray. So, bacterial isolate COJ1 can be explored for the field experiments as zinc adjuvant for the growth promotion of wheat plant.ThesisItem Open Access Symbiotic effectiveness of abiotic stress tolerant pigeon pea [Cajanus cajan (L.) millspaugh] rhizobia(CCSHAU, 2016) Boora, Sonu; Gera, RajeshPigeon pea [Cajanus cajan (L.) Millsp.], is a plant of Fabaceae family grown in semi-arid tropics in Asia and Africa. Pigeon pea is a versatile, stress-tolerant, and nutritious grain legume, possessing traits of value for enhancing the sustainability of dry sub-tropical and tropical agricultural systems. Environmental stress is a major component of natural selection in soil ecosystem. Among several environmental conditions, the most prominent problematic abiotic factors in the arid regions are drought, salinity and high temperature. Unlike legumes, rhizobia have high affinity to tolerate stress conditions. Hence, inoculation of stress tolerant strains of rhizobia may enhance the nodulation and nitrogen fixation ability of plants under stress conditions. So in the present study, 54 abiotic stress tolerant pigeon pea rhizobial isolates already existing in the department were checked for their purity on YEMA media and maintained on same medium for further studies. All these isolates were able to form nodules, when tested in cups under sterilized condition, however, 10 pigeon pea isolates showed better nodulation as compared to commercial rhizobial strain, 1021. Nitrogenase activity of these isolates was tested by using acetylene reduction assay (ARA) and only 9 isolates showed good nitrogenase activity, which ranged between 11- 208 nmoles ethylene h -1 tube -1 . Most of the rhizobial isolates were able to solubilize P and their P-solubilization index (P-SI) varied from 1.1 to 2.1 and 13-49µg TCP ml -1 on solid and liquid Pikovskaya’s medium, respectively. Ammonia excretion was also observed in most of the isolates, which varied from 0.5 to 4.53 µg ml -1 ammonia after 4 days of incubation, while bacteriocin production was observed only in 12 isolates. These isolates showed resistance towards ampicillin, nalidixic acid, chloramphenicol, neomycin and streptomycin up to a concentration of 100µg ml -1 , while some of the isolates were found to be sensitive to streptomycin and neomycin antibiotics even at a concentration of 10µg ml -1 . On the basis of nodulation efficiency under sterilized conditions and different agricultural useful traits, 10 multi-trait rhizobial isolates were selected to check their efficacy in pigeon pea under field conditions. The nodulation efficiency of all these rhizobial isolates in Micro plots under field conditions also found to be better than reference strain 1021 and un-inoculated control. These isolates also performed better in terms of shoot length, shoot dry weight, no. of branches, no. of pods, seed weight per plant, grain and straw yield as well as N & P uptake, when compared with control and reference strain, 1021 in Drought plots after harvest. Some of the pigeon pea rhizobial isolates like PPM37D, PPH8C, PPH10B and PPM33B, which performed better as compared to commercial strain, 1021 under field conditions, can be used as potential candidates for biofertilizer production in pigeon pea crop under rain-fed conditions.ThesisItem Open Access Impact of biochar on rhizospheric bacterial community structure(CCSHAU, 2016) Sihag, Khushboo; Rakesh KumarBiochar is a fine-grained, carbon rich, porous product remaining after plant biomass has been subjected to thermo-chemical conversion process (pyrolysis) at low temperatures in an environment with little or no oxygen. There is a wide variety of char products produced industrially. Biochar is added to soil with the intention to improve soil functions and to reduce emissions from biomass that would otherwise naturally degrade to greenhouse gases. It has been shown to change soil microbial community and composition which leads to change in functional ecology of microbial diversity. The composition of bacterial community in soils high in black C or biochar differs significantly from that of unmodified soils with the same mineralogy. Biochar amended soil samples were collected from IARI, New Delhi and a control soil without biochar was taken from the adjoining field. Physico-chemical properties of the soil sample such as EC, pH, field capacity moisture content, total N, P and K were estimated using standard procedures. It was observed that EC, pH, field capacity moisture content were increased after addition of biochar from 0.15 to 0.21, 7.4 to 7.6 and 24 to 39%, respectively. Microbial community structure analysis was performed using PCR-DGGE method. Soil DNA was extracted from the soil sample using Zymo Research Soil DNA Kit. Extracted DNA was amplified using 16S rDNA universal primers (27F &1378R). Seminested PCR was conducted using 986 F primer with GC clamp and 1378 R primer. Amplified 16S rDNA product was used as template DNA. The GC clamped 16S rDNA was run on DGGE (35-65% Denaturant). Most prominent bands in DGGE were eluted out following the prescribed protocol of Gene JET Gel Extraction Kit, purified and sequenced to identify the community using BLAST from NCBI. Dendrogram was constructed using NT-Sys software based on the banding pattern of DGGE. There was 80% similarity among non-amended biochar soil and 35% similarity with biochar amended soil suggesting wide diversity. Four prominent bands were eluted using Gene JET Gel Extraction Kit and sequenced. Present study concludes that the prominent microbial community belongs to uncultured Proteobacteria and Proteobacterium spp. In control soil, many uncultured bacterium spp. were found and Bacillus thuringenesis was found in biochar amended soil.