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8 Cards in this Set
- Front
- Back
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What do carotenoids do?
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- they accept excess energy from triplet stae chlorophyll, preventing the chlorophyll molecules from photoxidation.
- carotenoids then re-radiate this energy as heat. - if this energy is not dissipated by the carotenoids then signlet oxygen will form, leading to the destruction of chlorophyll and cell membranes. |
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What herbicides are the pigment synthesis inhibitors?
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Amitrole
Clomazone Fluridone Norflurazon Isoxaflutole Mesotrione |
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What is the mechanism of amitrole?
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- it inhibits the accumulation of chlorophyll and carotenoids
- in the absence of carotenoids, chlorophyll photooxidizes, resulting in bleached, whitened tissue - causes an inhibition of cell division and elongation |
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What is the mechanism of Clomazone?
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- blocks before farnesyl pyrophosphate, prevents formation of certain plant hormones, pigments
- inhibits phytol tail formation of chlorophyll molecule |
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Why is clomazone inactivated in put with an insecticide?
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Clomazone is a proherbicide so if it is put with an insecticide, it can't metabolize, by MFO, into an active ingredient
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What is the mechanism of fluridone and norflurazon?
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- specific site of action is a reversible and noncompetitive binding with the enzyme phytoene desaturase, preventing the conversion of phytoene to phytofluene
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What is the mechanism of Isoxaflutole?
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- toxic intermediate is produced from parent compound in the soil and the plant - diketonitrile derivative
- inhibits biosynthesis of the terpenoid pathway, which affects chlorophyll, carotenoid, gibberellin and abscisic acid levels - specifically inhibits 4-hydroxyphenylpyruvate dioxygenase (HPPD), which catalyzes the formation of homogentisate, a precurson for PQ which in turn reduces phytoene desaturase. Therefore, inhirectly inhibits phytoene desaturase similar to fluridone and norflurazon |
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What other herbicide inhibits HPPD?
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Mesotrione
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