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Subject: Plant Physiology × End date: 2015 × Start date: 2011 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Biochemical and molecular studies on post-harvest physiological deterioration of cassava (Manihot esculenta crantz)
    (Department of plant physiology, College of agriculture,Vellayani, 2015) Saravanan, R; KAU; Roy Stephen
    The project entitled “Biochemical and molecular studies on post-harvest physiological deterioration of cassava (Manihot esculenta Crantz)” was conducted at the Dept of Plant Physiology, College of Agriculture, Vellayani and at ICAR-CTCRI, Thiruvananthapuram during 2013 to 2015. The main objective of the work was to analyse the physiological biochemical and molecular mechanisms associated with post harvest physiological deterioration (PPD) and develop methods to delay the PPD in cassava. The initial screening of the cassava genotypes for their performance of PPD was done with 61 different genotypes including some released varieties. Significant differences were observed for PPD development and shelf-life of harvested roots. Cassava genotypes such as IMS2-8, 9S-172, 11S-53, IRS 2-10 and 9S-286 started showing the visible discolouration in the parenchyma tissue earlier (less than 3 days of storage). Genotypes such as 9S-7, 9S-98, 11S-31, 11S-86, 11S-14, CE63-3, CI43-2, CR43-2, CR54-A5, CR59-8R, Sree Athulya and Kalpaka showed low PPD scores and better shelf-life. Tissue imprinting for peroxidase enzyme showed that there was a remarkable increase in peroxidase activity in the root tissues with increasing PPD symptoms. There was no correlation between the root morphological traits and PPD severity. Carotene and starch content of root did not influence the PPD in the genotypes studied. Chemotypic profile of roots with PPD symptoms was used to classify the genotypes based on PPD. To develop an objective screening tool, Near Infrared Spectroscopy (NIRS) was utilized to analyse root samples for PPD. Principal component analysis (PCA) and chemometric tools clearly grouped the different PPD category in root tissues. Various stains such as saffranin, aniline blue, erythrocin, fast green and phloroglucinol stained the tissue specifically at vascular tissues and other cell components and were not suitable for detecting PPD. Storage techniques such as storing the harvested roots in de-aerated bags, wax coating and burying the roots under the soil were employed with selected cassava varieties like Sree Athulya, Sree Jaya, Vellayani Hrashwa, Kalpaka and Sree Padmanabha to delay PPD. Wax coating was suitable to reduce PPD for few weeks. Effect of different storage temperature on PPD was studied for five cassava varieties. Root respiratory flux was higher in roots stored at ambient conditions compared to high (40o C) or low temperature (4o C) storage. There were significant positive correlation between root respiratory flux at 3 and 9 days of storage to the CAT and POX activities studied in different cassava varieties. Roots were treated with various food preservatives at two different concentrations (0.5 and 1%). There was a weak, but significant reduction in symptom development in butylated hydroxy touline – (BHT, at 0.5 and 1% level) treated roots compared to other treatments. Nearly three folds increase in total phenol content was noticed in BHT and butylated hydroxy anisole (BHA) treated roots. The plant hormones related to wound response such as Salicylic acid and jasmonic acid were used to study the PPD response in roots under storage. The roots did not show marked influence to hormone application. Significant genetic variation was observed for PPD. The low PPD type genotypes such as 9S-7, 9S-98, 11S-31, 11S-86, 11S-14, CE63-3, CI43-2, CR43-2, CR54-A5, Sree Athulya and Kalpaka can be utilized for breeding programmes. High temperature storage of cassava at 40 oC resulted in reduced respiratory rate and increased antioxidant scavenging enzyme activity and also reduced the PPD. Differentiation of cassava roots at the metabolites level corresponding to visual symptoms and chemotypic profile of PPD and NIR spectroscopy offer a rapid screening tools. Among the different storage treatments, wax coating with antiseptic pre-treatment is most suitable and economical for increasing shelf-life of roots. Food preservatives like BHT and BHA have a significant, albeit marginal influence on PPD symptom development in cassava.
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    ThesisItemOpen Access
    Biochemical and molecular studies on post-harvest physiological deterioration of cassava (Manihot esculenta crantz)
    (College of Agriculture, Vellayani, 2015) Saravanan, R; KAU; Roy, Stephen
    The project entitled “Biochemical and molecular studies on post-harvest physiological deterioration of cassava (Manihot esculenta Crantz)” was conducted at the Dept of Plant Physiology, College of Agriculture, Vellayani and at ICAR-CTCRI, Thiruvananthapuram during 2013 to 2015. The main objective of the work was to analyse the physiological biochemical and molecular mechanisms associated with post harvest physiological deterioration (PPD) and develop methods to delay the PPD in cassava. The initial screening of the cassava genotypes for their performance of PPD was done with 61 different genotypes including some released varieties. Significant differences were observed for PPD development and shelf-life of harvested roots. Cassava genotypes such as IMS2-8, 9S-172, 11S-53, IRS 2-10 and 9S-286 started showing the visible discolouration in the parenchyma tissue earlier (less than 3 days of storage). Genotypes such as 9S-7, 9S-98, 11S-31, 11S-86, 11S-14, CE63-3, CI43-2, CR43-2, CR54-A5, CR59-8R, Sree Athulya and Kalpaka showed low PPD scores and better shelf-life. Tissue imprinting for peroxidase enzyme showed that there was a remarkable increase in peroxidase activity in the root tissues with increasing PPD symptoms. There was no correlation between the root morphological traits and PPD severity. Carotene and starch content of root did not influence the PPD in the genotypes studied. Chemotypic profile of roots with PPD symptoms was used to classify the genotypes based on PPD. To develop an objective screening tool, Near Infrared Spectroscopy (NIRS) was utilized to analyse root samples for PPD. Principal component analysis (PCA) and chemometric tools clearly grouped the different PPD category in root tissues. Various stains such as saffranin, aniline blue, erythrocin, fast green and phloroglucinol stained the tissue specifically at vascular tissues and other cell components and were not suitable for detecting PPD. Storage techniques such as storing the harvested roots in de-aerated bags, wax coating and burying the roots under the soil were employed with selected cassava varieties like Sree Athulya, Sree Jaya, Vellayani Hrashwa, Kalpaka and Sree Padmanabha to delay PPD. Wax coating was suitable to reduce PPD for few weeks. Effect of different storage temperature on PPD was studied for five cassava varieties. Root respiratory flux was higher in roots stored at ambient conditions compared to high (40o C) or low temperature (4o C) storage. There were significant positive correlation between root respiratory flux at 3 and 9 days of storage to the CAT and POX activities studied in different cassava varieties. Roots were treated with various food preservatives at two different concentrations (0.5 and 1%). There was a weak, but significant reduction in symptom development in butylated hydroxy touline – (BHT, at 0.5 and 1% level) treated roots compared to other treatments. Nearly three folds increase in total phenol content was noticed in BHT and butylated hydroxy anisole (BHA) treated roots. The plant hormones related to wound response such as Salicylic acid and jasmonic acid were used to study the PPD response in roots under storage. The roots did not show marked influence to hormone application. Significant genetic variation was observed for PPD. The low PPD type genotypes such as 9S-7, 9S-98, 11S-31, 11S-86, 11S-14, CE63-3, CI43-2, CR43-2, CR54-A5, Sree Athulya and Kalpaka can be utilized for breeding programmes. High temperature storage of cassava at 40 oC resulted in reduced respiratory rate and increased antioxidant scavenging enzyme activity and also reduced the PPD. Differentiation of cassava roots at the metabolites level corresponding to visual symptoms and chemotypic profile of PPD and NIR spectroscopy offer a rapid screening tools. Among the different storage treatments, wax coating with antiseptic pre-treatment is most suitable and economical for increasing shelf-life of roots. Food preservatives like BHT and BHA have a significant, albeit marginal influence on PPD symptom development in cassava.
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    ThesisItemOpen Access
    Marker assisted transfer of thermosensitive genic male sterility to high yielding red kernelled varieties of rice (Oryza sativa L.)
    (College of Agriculture, Vellayani, 2015) Niya, Celine V J; KAU; Roy, Stephan
    The project entitled “Marker assisted transfer of thermosensitive genic male sterility to high yielding red kernelled varieties of rice (Oryza sativa L.)” was conducted in the Department of Plant Physiology, College of Agriculture, Vellayani during 2011 to 2014. The main objectives were to develop molecular markers associated with TGMS gene and to transfer TGMS character to red rice background. For the present investigation, two TGMS lines were imported from International Rice Research Institute (IRRI) namely, TGMS1 and TGMS2which are from two different TGMS sources ID24 and IR32364 respectively. The TGMS lines along with two popular red rice varieties of Kerala, Uma and Jyothi were sown on monthly intervals for their initial phenological study. The critical sterility temperature and period of TGMS lines were characterised in the field using tracking method. The activity of antioxidant enzymes plays an important level in causing sterility in rice pollen grains, though the reason behind male sterility is unknown. Morphological, agronomic and floral traits were studied during the specific crop growth stage and were recorded as per the standard evaluation systems given by IRRI. Phenological, floral and morpho-agronomic characterisation of TGMS lines revealed that the line TGMS1 performed better with short stature, early maturity, more productive tillers, wider glume opening, higher panicle and stigma exertion, more filled grains and longer panicles. Stages of panicle development were determined by various methods viz., physical method, morphological index method and tracking method. The results have shown that TGMS1 is a better candidate for Kerala condition with critical sterility period of 15-22 days before heading and the sterility inducing average temperature of 27.25 o C. For hybridisation, TGMS1 plants were grown under sterility inducing condition and they were crossed with a popular red rice variety, Uma to produce F1. The F1 s were then selfed to get F2 population. A gene specific primer was designed for the red pericarp colour (Rc) which can be used as a background selection marker. Fifty F2 plants were used for marker analysis. Microsatellite analysis was done to find out the SSR markers polymorphic to the tms gene. DNA was isolated from the 50 F2 plants and performed PCR using 45 SSR markers. Capillary electrophoresis was done for the allele sizing of PCR products. Among 45 SSR markers used, three primers RM 3351, RM23 and RM31 could differentiate Uma, Jyothi andTGMS1, TGMS2. A set of twenty one primers were able to distinguish TGMS1 and Uma. The F2 plants sterile as per the TGMS markers were found to be sterile under sterility inducing condition. Under low temperature their fertility was transformed indicating the presence of tms gene. Linkage analysis using MAPMAKER version 3.0, seven linkage groups and a few unlinked primers were found. A segregation ratio of 2.57:1 was obtained between fertile and sterile lines. This ratio explains the monogenic nature of tms gene.Among 20 polymorphic markers, six (RM23, RM31, RM3351, RM 212, RM258 and RM244) were found significant. These on further analysis using χ 2-test revealed the possible association between the sterility phenotype and marker. From the present study, the sterility tms gene got successfully transferred into 14 sterile F2 plants and RM31, RM23, RM3351, RM212, RM244 and RM258 can be used for the evaluation of TGMS1 X Uma hybrids and their F2s.