Cumming 1969 has demonstrated that the short-day plant Chenopodium rubrum (60°47′ N) is induced to flower if inductive darkness is substituted by a relatively long exposure to a low intensity light of a low red/far-red ratio (light emitted by BCJ lamps). DCMU (3(3,4-dichlorophenyl)-1,1-dimethyl urea), a photosynthetic inhibitor, inhibited flowering if applied during this inductive BCJ light period.Our experiments show that ascorbic acid and dichlorophenol-indophenol (which have been used as reducing agents in photosynthesis by various workers) overcome the effect of DCMU on flowering. Sugars are also effective in overcoming the DCMU effect. This indicates that DCMU acts specifically on photosynthesis and that there are no side effects.In Cumming's experiments DCMU was supplied at the start of a BCJ inductive period and then washed off at the end of the BCJ period. However, there are indications that DCMU may persist in the plant for several days after the medium on which plants are growing has been thorou...
R. Sawhney, B. Cumming