THE MECHANISM OF ACTION OF FLUAZIFOP-BUTYL, HALOXYFOP-METHYL, AND SETHOXYDIM HERBICIDES ON WHEAT (TRITICUM AESTIVUM L.) SEEDLINGS (CHLOROPLAST DEVELOPMENT).
AuthorSATTI, MOHAMED AHMED EISA.
AdvisorBartels, Paul G.
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PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractHaloxyfop-methyl 2-[4-[ [3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoate, fluazifop-butyl (±)-2-[4-[ [5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoate, and sethoxydim 2- [1-(ethoxyimino)butyl]-5- [2-(ethylthio)propyl] -3-hydroxy-2-cyclohexen-1-one modified chloroplast pigment, growth, anatomy, and ultrastructure of pre- and postemergent-treated wheat (Triticum aestivum 'Pavon 76') seedlings. Seedlings were grown under 16 h photoperiod (105 μE/M²/S) at 32/24 C day/night temperature. Pigment, growth and anatomical studies were made on pre- and postemergent-treated seedlings. Postemergent treatments were applied to 6-day-old seedlings. Carotenoid levels were reduced by 90 to 94% in preemergent-treated seedlings at 5 x 10⁻⁵ M for each herbicide. Postemergent application of 10⁻³ M haloxyfop-methyl and sethoxydim caused a reduction of 11 and 15% in carotenoid concentration than the control, respectively. Also, they produced a significant reduction in chlorophyll a and total chlorophyll concentration. Preemergent treatment with 5 x 10⁻⁶ M of each herbicide caused a reduction of 78 to 91% in leaf fresh weight and 72 to 84% reduction in root dry weight as compared to the control. Height of the seedlings was reduced by 79 to 86% of the control. Postemergent treatments with 10⁻³ M of each herbicide reduced the length of the second leaf by 98%, whereas length of the first leaf was reduced by 36% following haloxyfop-methyl treatment and 45% following fluazifop-butyl or sethoxydim treatments. Fresh weight of leaf tissue treated with 10⁻³ M of each herbicide was reduced by 40%. Preemergent treatment of the seedlings with 3 x 10⁻⁶ and 5 x 10⁻⁶ M haloxyfop-methyl or with 5 x 10⁻⁶ M fluazifop-butyl or sethoxydim caused 35 to 50% enlargement of mesophyll cells as compared to the control. These cells appeared to contain less cytoplasm. Post- emergent application of 10⁻³ M of each herbicide caused swelling of mesophyll cells. Ultrastructural studies showed that plastids of seedlings germinated in 5 x 10⁻⁶ M of each herbicide were disrupted, swollen, and lacked internal thylakoids but contained masses of plastoglobuli. The chloroplasts of postemergent-treated seedlings had fewer granal and intergranal thylakoids, but the injury to plastids was less severe than in preemergent treatments.
Degree ProgramPlant Sciences