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    Item type:Publication,
    Differential accumulations of proline and flavonoids in indica rice varieties against salinity
    (2009-10-01) ;
    Cha-Um, Suriyan
    ;
    Four varieties of indica rice differing in salt sensitivity were used for comparative study of defense systems in response to salinity. Rice seedlings were transferred into the photoautotrophic system containing NB medium with 100 mM NaCl as a salt stress treatment for 4 days. The physiological responses of jasmine rice (KDML105) and Sangyod (SY) varieties showed the better tolerance to salinity than those of Pathumthani 1 (PT1) and Black Sticky (BS) varieties. In salt stress treatment, the relative water content (RWC) of rice seedlings was decreased when compared to untreated seedlings. The RWC of salt-tolerant seedlings (KDML105 and SY) were decreased (0.33-0.53%) less than those of salt-sensitive seedlings (PT1 and BS), which exhibited 1.18-2.63% reductions. The salt-tolerant KDML105 and SY showed the lesser extent of membrane damage (lipid peroxidation; 7.94-19.26%) while enhanced the proline level (56.56-78.56%) and the flavonoid level (1.72-3.48%) more than those of the sensitive PT1 and BS varieties. Moreover, the positive correlation between proline or flavonoid accumulations and RWC was observed whereas the correlation between proline or flavonoid accumulations and MDA content was negative. These results suggest that high proline and flavonoids levels accumulated in each varieties of rice might be closely related to tolerant abilities indicating by physiological performances.
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    Item type:Publication,
    An evaluation of water deficit tolerance screening in pigmented indica rice genotypes
    (2012-02-01) ;
    Cha-Um, Suriyan
    ;
    Eight pigmented genotypes of indica subspecies were geminated and then treated by mannitol-induced water deficit stress. A change of growth characteristics, photosynthetic pigments, lipid peroxidation, DNA content, proline content and anthocyanin accumulation in stressed seedling (100 mM mannitol) and control plant (0 mM mannitol) were calculated. Growth performances, photosynthetic pigment concentrations, and DNA contents in all rice genotypes were dropped whereas proline, anthocyanin contents and the lipid peroxidation levels were enriched. The stabilization in total photosynthetic pigment concentrations of stressed-seedlings were positively correlated to the proline or anthocyanin accumulation. In contrast, MDA content, the increases in the percentages of drought-stressed seedlings were negatively correlated to the proline or anthocyanin accumulation. The changes in biochemical, physiological and growth parameters were subjected to Ward's cluster analysis for water deficit tolerance. These cultivars could be classified into two groups, water deficit sensitive, SY, KD, KLD and TD49 and water deficit tolerance, KS, KK1, KK2 and BSR.