CuSO 4 filters influence flowering of Chrysanthemum cv. Spears

Abstract

`Spears' chrysanthemums ( Dendranthema × grandiflorum [Ramat.] Kitamura) were grown under solar filters filled with CuSO 4 in solution which absorbs FR, or water, which does not absorb FR, and were exposed to marginally long natural photoperiods, artificially long photoperiods, or artificially short photoperiods. Internode length and plant height were reduced under CuSO 4 filters compared to plants grown under water filters, regardless of photoperiod. Plants grown under water- or CuSO 4–filled filters that received artificial short days flowered 7 days ahead of the plants grown in natural, marginally long photoperiods under CuSO 4 filters and 17 days ahead of the plants grown under water filters and receiving natural, marginally long photoperiods. The number of nodes was the same for the plants grown in short and marginally long days under CuSO 4 filters and in short days under water filters, indicating that flower induction occurred simultaneously in these treatments. Development of additional nodes on plants under water-filled filters and receiving natural long-days indicated that floral induction was delayed. A cool white fluorescent light night break prevented or delayed flowering of plants grown under water- and CuSO 4–filled filters during natural short days. The results demonstrate that standard practices of photoperiodic control can be used to time chrysanthemums `Spears' grown under CuSO 4 filters for pot mum production.