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Subject: Plant Biochemistry × Author: Shashikumara R. × End date: 2017 × Start date: 2012 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Enzymatic and Metabolic Studies of Salinity Stress Response in Rice (Oryza sativa L.)
    (University of Agricultural Science, Dharwad, 2016-06) Shashikumara R.; Mirajkar, Kiran K.
    A pot experiment was conducted at Main Agriculture Research Station, University of Agricultural Sciences, Dharwad during 2015 - 2016. The experiment was conducted in factorial CRD with three replications. Salt stress can lead to increase in the generation of reactive oxygen species (ROS) such as superoxide, hydrogen peroxide, hydroxyl radical and oxygen and plants possess complex antioxidative defense system comprising of non-enzymatic and enzymatic components to scavenge ROS. The current work aims to study the defense mechanism of rice genotypes (CSR 23 and BPT 5204) to salinity and the activity of the defensive enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), nitrogen assimilatory enzymes such as nitrate reductase and nitrite reductase in both leaves and roots, the amounts of total phenol, reducing sugar and chlorophyll content in leaves were analyzed in different levels of salinity (0, 8, 12 and 16 dSm-1). Salinity stress increased the activity of catalase, glutathione reductase and superoxide dismutase and total phenol content in both the genotypes, but the level of increases was high in CSR 23 compare to BPT 5204. Nitrogen assimilatory enzymes such as nitrate and nitrite reductase were very sensitive to salt stress and both the genotypes showed decreased activity under salinity. A decrease in reducing sugar content in both the genotypes i.e. percentage decreases was high in BPT 5204 compare to CSR 23 and photosynthetic pigments such as chlorophyll ‘a’, chlorophyll ‘b’ and total chlorophyll was observed in the leaves of rice genotypes under salinity stress. Photosynthetic pigments high in control and decreases in salinity stress. The improved performance of salt tolerant genotype (CSR 23) was associated with more efficient antioxidant system response under conditions of stress compare to salt sensitive genotype (BPT 5204).