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2017 - 20202
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Subject: Plant Physiology × Author: Rawat, Pratibha × Start date: 2015 × Type: Thesis ×
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    ThesisItemOpen Access
    Implications of indigenous phosphate solubilizing bacteria in association with phosphorus fertilizer on growth dynamics, phosphorus biofortification and yield attributes in upland rice (Oryza sativa L.) under field conditions
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2020-10) Rawat, Pratibha; Shankhdhar, S.C.
    The present investigation was an attempt to evaluate the impact of phosphate solubilizing bacterial strains viz., Bacillus licheniformis, Pantoea dispersa, and Staphylococcus sp. isolated from paddy rhizosphere on growth, phosphorus biofortification, phosphorus related efficiencies, and yield parameters in rice genotype Pant Dhan 26 under upland conditions. A field experiment was laid out in split-plot design during the Kharif season of 2018 and 2019 in triplicates with nine treatments viz., T1- uninoculated control with 0%, 50%, 75%, and 100% recommended phosphate fertilizer dose (i.e. 45 kg P2O5 ha-1); T2- PSB1; T3- PSB2; T4- PSB3; T5- PSB1+PSB2; T6- PSB1+PSB3; T7- PSB2+PSB3; T8- PSB1+PSB2+PSB3; T9- Standard PSB strain. The rice plants treated with PSB alone or in combination with varied phosphate fertilizer doses showed improved growth traits like plant height, leaf area index, leaf and culm dry weight, root parameters, and total dry matter as well as physiological attributes like flag leaves chlorophyll and carotenoid content, chlorophyll fluorescens, and antioxidants compared to uninoculated control. A significant increment in yield parameters like panicle weight, panicle length, spikelet fertility, grain yield, and harvest index was recorded in all PSB treated plants blended with phosphate fertilizer rates compared to control plants. Phosphorus uptake in grains and vegetal tissues, and phosphorus use efficiency was significantly augmented in the consortium of PSB blended with 50% fertilizer rate. Iron content improved significantly in all the PSB treated plants whereas zinc content and disease incidence reduced in PSB treated plants compared to control plants. The present findings provide an overview that PSB alone or their consortium blended with an optimum 50% recommended phosphate fertilizer dose can be an effective strategy for biofortification of crops in an eco-friendly and economical manner for a sustainable agriculture system.
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    ThesisItemOpen Access
    Physiological and biochemical characterization of rice genotypes for low light stress tolerance
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2017-06) Rawat, Pratibha; Bains, Gurdeep
    Rice is a global food for more than 60% of the world’s population. It is very sensitive to environmental factors such as temperature, light, drought etc. during critical stages of growth, such as flowering and seed development. Low light stress is an important constraint for rice productivity in Southeast Asia. For physiological and biochemical characterization of rice genotypes for low light stress tolerance, a field experiment was conducted in Norman E. Bourlog crop research center, G. B. Pant University of Agriculture and Technology, Pantnagar during kharif season 2016 with different rice genotypes, namely, IET 24195, IET 24183, IET 24189, IET 24188, Vivekdhan 86, IET 24197, IET 24192, IET 25149, IET 25157, Shalimar Rice 3, IET 25144, IET 25154, IET 27P63, US-314, Tulasi and Swarnaprabha, respectively. These genotypes were transplanted in two blocks, one for control and another block for imposing low light stress by covering the block with 50 % shade net supported by bamboo sticks. Both the entry ends were open for sufficient ventilation. A number of parameters such as plant height, tiller number, leaf area, chlorophyll, protein, carbohydrate, amylose, phenol and Zinc content, grain yield, thousand grain weight and spikelet fertility, total dry matter, root length, root weight, stem weight, panicle number were recorded in different rice genotypes and it was found that except plant height and chlorophyll content, all the parameters reduced significantly under low light stress. The genotypic variations in these characteristics were also found. Some genotypes showed tolerance for low light stress and some were found to be susceptible. Finally the grain yield, harvest index, number of filled spikelet and percent spikelet fertility indicated that low light stress adversely affected these parameters. The low light stress tolerant genotypes performed better in terms of filled grain numbers and percent spikelet fertility per panicle, harvest index as compared to susceptible genotypes. In present study, US-314, IET 27P63, and Swarnaprabha were found to be tolerant. Low light stress effect on soil microbial community was also studied by molecular methods like RT PCR and DGGE and it was found that low light stress significantly reduced the soil microbial community as compared to control conditions.