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8 Cards in this Set

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  • Back
What do carotenoids do?
- 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.
What herbicides are the pigment synthesis inhibitors?
What is the mechanism of amitrole?
- 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
What is the mechanism of Clomazone?
- blocks before farnesyl pyrophosphate, prevents formation of certain plant hormones, pigments
- inhibits phytol tail formation of chlorophyll molecule
Why is clomazone inactivated in put with an insecticide?
Clomazone is a proherbicide so if it is put with an insecticide, it can't metabolize, by MFO, into an active ingredient
What is the mechanism of fluridone and norflurazon?
- specific site of action is a reversible and noncompetitive binding with the enzyme phytoene desaturase, preventing the conversion of phytoene to phytofluene
What is the mechanism of Isoxaflutole?
- 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
What other herbicide inhibits HPPD?