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2019 - 201912020 - 20231
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Author: Kiranjot Kaur × Start date: 2019 × Type: Thesis × Thesis Type: M.Sc ×
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    Prospecting plant growth promoting and endophytic bacteria for improving growth and yield of sunflower (Helianthus annuus L.)
    (Punjab Agricultural University, 2023) Kiranjot Kaur; Vyas, Pratibha
    The current study was carried out with the aim to develop a plant growth-promoting bacterial inoculant for improving the growth and yield of sunflower. A total of 64 morphologically distinct bacteria were isolated from leaves, stem, roots and rhizosphere of sunflower collected from the fields of Punjab Agricultural University, Ludhiana. The isolates were screened for multifarious plant growth-promoting traits viz. solubilization of phosphate and zinc; production of auxins, siderophore, ammonia, hydrogen cyanide, and growth on nitrogen free medium. Thirty-three bacterial isolates showed solubilization of phosphate with solubilization index ranging from 2.7 to 3.8 by rhizospheric bacteria and 2.4 to 5.4 by endophytic bacteria on modified Pikovaskaya agar. In liquid medium, phosphate solubilization ranged from 3.6 to 171.6 μg/ml by the rhizospheric bacteria and 1.1 to 889.5 μg/ml by endophytic bacteria. Thirty isolates showed zinc solubilization, 25 isolates showed siderophore production while 40 isolates showed luxuriant growth on different nitrogen free media. All the isolates were positive for auxin and ammonia production but negative for hydrogen cyanide production. Based on multiple plant growth-promoting traits, nine potential bacterial strains were tested for growth promotion of sunflower in pots. The isolates showed a significant increase in growth, chlorophyll content and N, P and K contents of plant and soil samples with the bacterial inoculations over the uninoculated control. Three isolates showing the highest growth promoting activity were identified by phenotypic features, biochemical tests and MALDI-TOF-MS analysis as Pseudomonas aeruginosa SRB1, Advenella kashmirensis SLE1 and Brevendimonas dimunata SLE15. The field evaluation of three potential bacterial strains Pseudomonas aeruginosa SRB1, Advenella kashmirensis SLE1 and Brevendimonas dimunata SLE15 and their consortium was carried out with and without 75 and 100 per cent recommended dose of fertilizers for sunflower. The highest growth promotion, nutrient content and yield enhancement was recorded with the treatment AkSLE1 + BdSLE15 + PaSRB1 with 100 per cent RDF which was statistically not different from that obtained with the treatment AkSLE1 + BdSLE15 + PaSRB1 with 75 per cent RDF, indicating the potential of these three PGPB strains in saving around 25 per cent N, P and K fertilizers for sunflower. The study has led to the selection of a plant growth-promoting bacterial consortium as a potential bacterial inoculant for improving the growth, yield and nutrient content in sunflower.
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    ThesisItemOpen Access
    Influence of ohmic heating on electrical properties of tomato puree
    (Punjab Agricultural University, Ludhiana, 2019) Kiranjot Kaur; Paramjit Singh
    Ohmic heating is a green processing technique that is different from other processing methods. In this process electric current is allowed to pass through the food sample and heating occurs due to inherent resistance of sample. It is highly efficient technology and provides rapid and uniform heating. In this study, ohmic heating treatment was applied to different concentrations (100, 90, 80, 70 and 60%) of tomato puree. The puree was ohmically heated from 30 to 70⁰C at four different voltage gradients of 8, 6, 4 and 2V/cm for different concentrations. Measurements have been made on electrical conductivity, ohmic heating rate, density, pH, TSS and specific heat. The voltage gradient and concentration has significant effect on electrical conductivity of tomato puree. Electrical conductivity and ohmic heating increases linearly with rise in temperature, concentration and voltage gradient. pH and TSS are also noted before and after the ohmic heating treatment. Statistical analysis has been conducted and observed that this treatment has no significant effect on pH and TSS values. System performance coefficient was also calculated for ohmic heater at different voltage gradients and observed that as the concentration of tomato puree decreases the efficiency of ohmic heating apparatus shift towards higher voltage gradient in prescribed voltage range.