| Summary: | 碩士 === 國立中興大學 === 農藝學系 === 90 === This study was conducted to investigate seedling growth response of rice to glyphosate, and explore the physiological mechanism of differential tolerance of glyphosate in rice lines.
According to the analysis of does-response to glyphosate for the six growth characters including plant height, fresh weight and dry weight of shoots and roots, and injury index of rice, cv. TNG 67, seedlings at V3 stage, 3.31 mM of glyphosate was used to screen tolerant and susceptible lines. In addition, dose-response to glyphosate was also tested in suspension cell cultures, and this response was more sensitive that in whole plant.
After three times of screening, two lines, NY 1376 and GS 12, were referred as a tolerant and a susceptible line, respectively. A large accumulation of shikimic acid and a decrease of aromatic amino acids in susceptible line, suggested that the EPSPS activity in susceptible line was more inhibited by glyphosate.
Regard to the differential tolerance between two rice lines, both absorption and metabolism of glyphosate were seemly not involved, in the tolerance mechanism. However, little glyphosate accumulation was found in leaves above treated leaf, i.e. the apical meristem, for the tolerant line. And more glyphosate translocated to this part for the susceptible line, suggesting that the different partition patterns of glyphosate between two lines meight result in differential tolerance to glyphosate.
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