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2016 - 20172
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Subject: Agricultural Biochemistry × End date: 2017 × Start date: 2012 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Seed Deterioration and Biochemical Changes Associated with Accelerated Ageing in Groundnut (Arachis hypogaea L.)
    (University of Agricultural Science, Dharwad, 2017-07) Gautam Kumar; Olekar, Nagaratna S.
    Studies to determine the extent of loss in seed viability in groundnut (Arachis hypogaea L.) under accelerated ageing condition, and to identify important deteriorative processes that induce cellular debility within kernels and pods were carried at the Department of Biochemistry, University of Agricultural Sciences, Dharwad during 2016-17. Two genotypes of groundnut viz., GPBD-5 and DH-86 were aged under accelerated ageing chamber (45° C and 90 % RH) up to eight days at two days interval for viability tests and biochemical analysis. The experiment was laid out in two factorial Completely Randomized Design with four replication. The results indicated a significant variations for the seed quality parameters due to accelerated ageing for different intervals. Seed deterioration was evident from losses in seed viability and vigour from (2042 to 584) i.e 71.40 %, electrolyte leakage from (0.25 to 1.56 dS m-1) i.e 16.02 %, loss in lipid content and changes in enzymes activity. An increase in lipase activity from (0.50 to 0.76 µ eq of free fatty acid released/ min) i.e 52 % and decrease in β-amylase activity from (1.46 to 0.92 µmol/min/mg of protein) i.e 36.98 % were recorded. Other biochemical changes due to ageing include increase in total soluble sugar (107.35 to 189.20 mg/g) i.e 76.24 % and decline in total soluble protein from (159.50 to 141.50 mg/g) i.e 11.28 %. Among the two genotypes, GPBD-5 was superior over DH-86 in all the seed quality parameters and biochemical analysis due to ageing. Physiological and biochemical changes due to accelerated ageing were similar to those which can observed during natural ageing. This study can be useful for comparison and selection of genotypes for better resistance to ageing and gives a clear picture of the effect of accelerated ageing on the mode of deterioration in the seeds of groundnut genotypes when stored in pod and kernel form.
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    ThesisItemOpen Access
    Biochemical Investigation of Biotic Stress Response of Mango (Mangifera indica L.) to Powdery Mildew Disease
    (University of Agricultural Science, Dharwad, 2016-07) Hipparagi, Laxman; Olekar, Nagaratna S.
    Plants respond to various biotic and abiotic stresses through the production of large amounts of reactive oxygen species (ROS). The research work aimed to study the defense mechanism of locally grown mango (Mangifera indica L.) varieties (Neelum and Totapuri) and hybrids (Neelgoa and Mallika) against mango powdery mildew. This study was attempted to evaluate the role of phytochemicals (total phenol, reducing sugar and antioxidant enzymes) as defence response against powdery mildew infection in mango genotypes. A number of biochemical compounds including sugars, phenolic compounds, superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), polyphenol oxidase (PPO) and ascorbate oxidase (AO) have been implicated to play a crucial role in the tolerance/resistance of different mango cultivars to powdery mildew infection. After powdery mildew infection, there was increased antioxidant enzyme activity in all infected leaves compared to healthy leaves. Among all genotypes Mallika showed higher activity for all the enzymes mentioned above except in case of glutathione reductase activity and lower antioxidant activity of all enzymes were observed in Neelum except in case of glutathione reductase where in lower activity was observed in Totapuri. The total phenols were observed more in Neelum compared to other genotypes and lower phenols were observed in Neelgoa. Reducing sugar decreased because of powdery mildew infection and higher sugar content was observed in Neelum where as lower content was recorded in Mallika. As powdery mildew disease infects mainly to leaf portion because of this chlorophyll content was reduced. The higher total chlorophyll content was observed in Mallika and lower content was recorded in Neelum due to disease infection. This study underlines the significance of enzymatic ROS scavenging system in disease resistance/susceptibility.