End-of-day far-red treatment enhances responsiveness to gibberellins and promotes stem extension in chrysanthemum

Abstract

SUMMARYA brief end-of-day (EOD) far-red (FR) exposure promotes extension growth in plants. This change suggests a role for gibberellins (GA). For chrysanthemum (Chrysanthemum morifolium Ramat.), we show that EOD-FR exposure enhances shoot extension and is mediated, at least in part, by increased responsiveness (sensitivity) to GA. In addition, our analysis showed how light, especially EOD-FR, influenced shoot extension. The effect of EOD-FR on promoting extension growth was maintained, not only during the dark period, but also in the subsequent light period. Furthermore, our observations suggest that dark reversion of certain phytochromes is involved in the determination of flowering time. We also discuss the applicability of EOD-FR treatment to reduce the overall duration of cultivation, while maintaining a sufficient stem height during cut chrysanthemum production.