Carbon partitioning within organs after 9 h of low R:FR. Cotyledon (A), hypocotyl (B), and root (C) samples of 5-d-old seedlings grown in long days, harvested after a 1-h chase following exposure to a 10-min pulse of 14CO2, 9 h after start of light treatment. Samples were processed into primary fractions of ethanol-soluble, H2O-soluble, and insoluble components. The water-soluble fraction was further fractionated into basic, acidic, and neutral fractions and the insoluble fraction into starch and a remaining fraction containing proteins and cell walls (D). Data represent means ± 2 SE; n = 4. Asterisks indicate significant difference. Significance codes: *0.05 > P > 0.01, **0.01 > P > 0.001, and ***P < 0.001.