Mesotrione, topramezone, and tembotrione inhibit 4-hydroxyphenylpyruvate dioxygenase (HPPD), an enzyme integral to carotenoid biosynthesis. Research was conducted to evaluate the efficacy of visual bleaching and chlorophyll fluorescence yield (F v/F m) measurements for estimating common bermudagrass [Cynodon dactylon (L.) Pers.] carotenoid and chlorophyll concentrations following mesotrione (0.28, 0.35, and 0.42 kg ha -1), topramezone (0.018, 0.025, and 0.038 kg ha -1), and tembotrione (0.092, 0.184, and 0.276 kg ha -1) applications. Measurements of VB and F v/F m were evaluated 3, 7, 14, 21, 28, and 35 d after application. Leaf tissues were sampled on the same dates and assayed for chlorophyll and carotenoid compounds by using high-pressure liquid chromatography methodology. Carotenoid and total chlorophyll concentrations were regressed upon VB and F v/F m on each evaluation date. While significant (P < 0.05) relationships were detected on each date, variation explained by linear regression was modest (R2 < 0.65); thus, neither VB nor F v/F m assessments are good predictors of carotenoid and chlorophyll concentrations after HPPD-inhibiting herbicide treatment. Comparisons of R2 values for VB and F v/F m data suggest no advantage in using F v/F m in place of VB measurements when evaluating HPPD-inhibiting herbicide activity.
All Science Journal Classification (ASJC) codes
- Agronomy and Crop Science