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20215
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Subject: Plant Physiology × End date: 2021 × Start date: 2021 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Effect of shade stress on physiological, biochemical and agronomic traits of various rice (Oryza sativa L.) genotypes
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2021-09) Bhatt, Priyanka; Shankhdhar, S.C.
    Rice (Oryza sativa L.) is the world single most important food crop, being the primary source for more than one third of the world population. Rice is not only the most widely used food crop by a third of the population of the world, but it has also been established as the model monocot plant for study. Rice is extremely sensitive to the environmental factors as, solar radiation, temperature, rainfall, relative humidity and wind. Light is one the most important factor that determines plant growth and development. In some areas of the world with continuously cloudy weather or rainfall, rice yields can be reduced by 30% to 50% indicating that low light is an indispensable problem for rice production. For the Morpho - physiological, biochemical and agronomic responses of rice (Oryza sativa L.) under low light stress condition, a field experiment was conducted in A2 block of Norman E. Borlaug crop research center, G.B. Pant University of Agriculture and Technology, Pantnagar during Kharif season 2020 with twenty one rice genotypes namely, IET 27537, IET 27547, IET 28264, IET 28276, IET 28281, IET 28283, IET 28286, IET 26692, Pooja, IET 26744, Swarnaprabha, IET 29025, IET 29026, IET 29027, Gayatri, IR-8, IET 29029, IET 29030, IET 29031, IET 29032, IET 29033. Swarnaprabha was taken as a check variety among all the parameters. All twenty one genotypes were transplanted in two blocks control i.e., normal light and treatment i.e., which was imposed with low light stress by covering the blocks with 50% shade net supported by bamboo sticks and both the entry ends were left open for proper ventilation. Among the twenty one genotypes only five genotypes attained maturity specifically, IET 28281, IET 29025, IET 29027, Gayatri, and Swarnaprabha. Several parameters namely, plant height, tiller number, leaf area index, leaf dry weight, stem dry weight, total dry matter, panicle number, panicle weight, spikelet number, filled grains, thousand grain weight, grain yield, harvest index, chlorophyll content, carbohydrate content and malondialdehyde content were recorded for the rice genotypes and it was recorded that except plant height, leaf area index, chlorophyll content all the parameters significantly reduced under low light stressed conditions. Due to some genotypic variations some genotypes were regarded as the tolerant genotypes and some as the susceptible genotypes. The low light tolerant genotypes performed better in terms of grain yield, harvest index in comparison to less tolerant and susceptible genotypes. In the present study, genotype IET 28281 was found highly tolerant to low light stress followed by moderately tolerant genotype IET 29027 and the genotype IET 29025 was found least tolerant to low light stress. A positive correlation of most of the morpho-biochemical and yield parameters with grain yield at control (normal) light conditions and a negative correlation of these parameters were found at low light conditions.
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    ThesisItemOpen Access
    Physiological characterization of rice (Oryza sativa L.) genotypes grown under multiple abiotic stresses
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2021-01) Sharma, Diksha; Shankhdhar, Deepti
    Various abiotic stresses limit rice production in the environments, which comprise about 45% of the global rice area. From several years breeders are trying to solve this problem and develop many stress tolerant rice varieties that could be easily accepted by farmers in antagonistic environments. Important stresses include drought, submergence, salinity and cold stress. The present study was aimed at assessing the response of 23 rice genotypes to different levels of mannitol (1% and 2%) as drought stress, salinity using NaCl concentration as salt stress under hydroponic conditions, submergence in 10 cm standing water and cold stress at early seedling stage. The experiment was replicated three times in a Completely Randomized Design. The 23 rice genotypes evaluated for percent germination, root length, dry root weight, shoot length, dry shoot weight, seedling vigour, total chlorophyll content and sodiumpotassium content. Overall reduction was observed in all the morphological (germination percentage, root length, shoot length, root weight, shoot weight and seedling vigour) and physiological parameters (chlorophyll content).Further, six genotypes were selected, two as tolerant, two as moderately tolerant and two as sensitive on the basis of seedling vigour. The sodium content was enhanced under salt stress in the selected genotypes whereas the potassium content was declined in both root and shoot of the seedling. Positive co-relation was observed between total chlorophyll content and seedling vigour of the genotypes with R value = 0.681274. Total proline and protein content of the seeds of selected genotypes was determined which was highest for the tolerant genotypes and lowest for the sensitive one. The interaction between treatments and the genotypes was significant for all the parameters. Several criteria are needed to make a tolerant variety adoptable by the farmers because they seek for adequate grain qualities in the stress tolerant high yielding varieties.
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    ThesisItemOpen Access
    Morpho-physiological and biochemical assessment of heat tolerance in various rice (Oryza sativa L.) genotypes
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2021-02) Thakur, Roshan Suresh; Shankhdhar, S.C.
    Rice is a staple food crop in global food system fulfilling the energy requirement of major part of world 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. High temperature can irreversibly damage the rice grain quality, yield and plant processes. A research investigation was carried out to evaluate the effect of high temperature stress on morphophysiological and biochemical parameters; and to study the yield attributes of different rice genotypes under heat stressin B1 block of N. E. Borlaug crop research center, Pantnagar during kharif season 2019. Heat treatment was given to different rice genotypes during flowering by making a polythene tunnel in one block which traps heat and other block kept open as control. Both the ends were open for sufficient ventilation. Among 30 genotypes only five genotypes, viz., Vandana, IET 28417, N-22, IET 28409 and IET 27908 were selected for the further research work on the basis of their sensitivity to high temperature and on yield attributes. Parameters such as plant height, effective tiller number, total dry matter, leaf area index, chlorophyll content, chlorophyll fluorescence, stem weight, panicle weight, number of filled grains per panicle, number of spikelet, spikelet fertility, test weight, grain yield, harvest index, total carbohydrate and protein content of harvested seeds etc. were recorded. It was found that chlorophyll fluorescence, leaf weight, stem weight, panicle weight and TDM reduced after flowering. At maturity, there was a decrease in shoot weight, TDM, panicle weight, spikelet fertility, grain yield, harvest index andproteindue to high temperature. Physiological and biochemical analysis revealed that the carotenoid content and LAI were increased in all; whereas, carbohydrate, chlorophyll a, chlorophyll b content, test weight, spikelet number, grain number, panicle number, effective tillers and plant height were increased/decreased in some genotypes. The parameters which were positively correlated with grain yield were leaf weight, stem weight, panicle number, panicle weight, shoot weight, and TDM whereas test weight was negatively correlated. Genetic diversity was responsible for the stress effects and stress mitigation in the crop as different genotypes from diverse backgrounds showed varied results; since, out of five genotypes, IET28417 was found to be tolerant while IET 27908 and Vandana were sensitive to high temperature in the present investigation.
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    ThesisItemOpen Access
    Physiological and biochemical responses of rice (Oryza sativa L.) genotypes grown under fifty percent shading conditions
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2021-02) Tamta, Akashdeep; Shankhdhar, S.C.
    Rice (Oryza sativa L.) is imperative to the greater part of the world's population. It serves as most consumed cereal crop by mankind. Temperature, solar radiation, rainfall, pH, relative humidity and wind directly impacts the production and various growth stages during its developmental stages. Intensity of light determines the basic character of rice growth and development. Continuously cloudy weather and rain fed conditions particularly during grain filling period result in low quality of grain and loss in yield, yield attributes. For Physiological and biochemical responses of rice (Oryza sativa L.) genotypes were grown under fifty percent shading at B1 Block of Dr N. E. B CRC and department of Plant Physiology of GBPUA&T Pantnagar during kharif season 2019 with different rice genotype, namely IET 27570, IET 27571, IET 27572, IET 27577, IET 27581, IET 27584, IET 27586, IET 27588, IET 26687, IET 27590, IET 27592, IET 27595, IET 27596, IET 27597, IET 27598, IET 27559, Swarnaprabha and IR-8.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 and both the entry ends were open for sufficient ventilation. Among 18 genotypes only seven genotypes attained maturity namely IET 27572, IET 27584, IET 27588, IET 27590, IET 27592, IET 27559 and Swarnaprabha. Among all parameters it was found that except plant height and chlorophyll content, all the parameters reduced significantly under low light stress. Some genotypes showed tolerance for low light stress and some were found to be susceptible. Finally the grain yield, harvest index and number of filled spikelet indicated that low light stress adversely affected these parameters.Genotype IET 27588 was found to be tolerant for low light stress and performed better because it attained highest grain yield, harvest index and spikelet fertility under the low light stress condition, followed by moderately tolerant genotypes IET 27592.
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    ThesisItemOpen Access
    Elucidating the impact of applied silicon on improving biotic and abiotic stress tolerance in rice (Oryza sativa L.) genotypes
    (G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2021-01) Singh, Nancy; Atul Kumar
    Rice is the staple food for more than three billion people in the world. With increasing global population, the demand for rice has been steadily increasing. Rice yield has been significantly increased over the recent decades. However, due to various reasons like low profitability of crop production, limited access to new agricultural technologies and climate change, “the objective of increasing rice yield per unit area with less harmful impact to the environment has become a major global concern.” In rice cultivation, fertilizers represent about 19% of production costs; however, proper fertilization management helps increase performance and could reduce production costs and increase crop yields. Silicon is attributed with many beneficial effects for the cultivation of rice, as it increases the tolerance to abiotic and biotic stress. This nutrient reinforces the cell wall and, thereby, increases the biomass and grain production. A field experiment was performed in split-plot design replicated thrice with four treatments viz., T1: Control, T2: Si fertilized T3: Si + water stress and T4: water stress. Stress was imposed by withholding irrigation 12 days prior to flowering and again 10 days after anthesis. The experiment was conducted during the kharif season of 2019 to evaluate the influence of foliar applied Si on biotic and abiotic stress tolerance in different rice genotypes. Various morphological, yield attributes and biochemical parameters in nine genotypes namely IIRRH-122, IIRRH-131, IIRRH-132, HRI-174, KRH-4, JKRH-3333, US-314, 27P63 and Sahabhagidhan were observed. Silicon displayed positive influence on the growth and development and yield under both well watered as well as water-deficit conditions. Growth parameters such as plant height, tiller number, leaf number, LAI and biomass accumulation as well as yield and yield attributes such as panicle number, spikelet number, grain number, test weight and harvest index were found to enhance. The biological yield was recorded to be increased by 16% and grain yield increased by 26% under stress. Chlorophyll by 31%, protein by 17% and carbohydrate content by 49% were enhanced on application of silicon under stress. The insect and pest infestation decreased under silicon application. A decrease of 49% was recorded in stem borer and leaf infestations while blast disease decreased by 33% and blight by 41% under stress. Genotypes IIRRH-132, KRH-4 and US-314 showed great response to silicon fertilization under well-watered as well as water deficit conditions.