Figure 1.

Measurements of H₂O₂ levels during development of field-grown cotton fibers. Flowers of field-grown cotton were tagged at anthesis and bolls were collected at the indicated times postanthesis. A, H₂O₂ was determined in detached fibers according to the method of Snell and Snell (1949). B, H₂O₂ production was followed in whole locules by incubating them in DCFDA for 60 min. 2′,7′-Dichlorofluorescein, the H₂O₂-dependent oxidation product, was measured at indicated times at 485-nm excitation and 525-nm emission wavelengths. Catalase (x) was added to the 19-DPA sample. 9 DPA (♦), 19 DPA (▴), and 26 DPA (▪). d.w., Dry weight.