Thumbnail Image

Thesis

Browse

2019 - 201912020 - 20232
Reset filters
Author: Kiranjot Kaur × Start date: 2019 × Thesis Type: M.Sc ×
Reset filters

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    ThesisItemRestricted
    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.
  • Thumbnail Image
    ThesisItemRestricted
    Evaluation of Micro and Nano Emulsions of Monarda citriodora Essential Oil Against Penicillium digitatum
    (Punjab Agricultural University, Ludhiana, 2022) Kiranjot Kaur; Tandon, Ritu
    Postharvest fungal pathogenic invasions are the major root cause of reduced shelf life of kinnow fruit, thereby contributing to the postharvest losses. Development of eco-friendly alternates are the need of the hour owing to health safety concerns for replacing the ongoing synthetic fungicide use. Essential oils with promising antimicrobial activities offer a promising solution but their hydrophobicity poses a big hindrance for exploiting the same. Present work was planned to explore their antimicrobial potential by developing their hydrophilic formulation with the use of nanotechnology. An in vitro study was conducted to assess the efficacy Monarda citriodora essential oil and its emulsions against major postharvest fungal pathogen of Kinnow; Penicillium digitatum. The total phenol and flavanoid content in Monarda citriodora essential oil is estimated to be about 28.3 µg ml-1 and 35.54µg ml-1 respectively. Both micro and nanoformulations were prepared for different ratios of Monarda citriodora essential oil (0.5 to 3%) with different surfactant combinations and oil-surfactant-ratios of 1:1 to 1:3. The influence of several process factors such as surfactant and oil phase concentrations, as well as sonication time intervals, on emulsion stability was investigated using droplet diameter, Polydispersity index (PDI) and zeta (δ) potential. An emulsion formulated with 1% oil and 1:1 OSR and treated with ultrasonic waves for 15 min was optimized with droplet diameter of 52.2 nm, 0.245 PDI, and -21 mV of δ potential with consistent stability till 1 month. Further, in vitro antifungal activity of the optimized Monarda citriodora essential oil nanoemulsion exhibited the best efficacy with 100% inhibition at 200 mg L-1. The treated Monarda citriodora essential oil emulsions showed morphological alteration with additional reduction in hyphal diameter on optical micrographs. Further studies need to be conducted to explore the potential of Monarda citriodora essential oil nanoemulsions for enhancing shelf life of Kinnow fruits.
  • Thumbnail Image
    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.