Critical day-length and photoinductive cycles for the induction of flowering in halophyte Suaeda salsa

Abstract

Seedlings of Suaeda salsa were exposed to various day lengths (8, 10, 12, 14, 15, 16 h) and with various numbers of photoinductive cycles when the fifth leave appeared on the plant. Plants formed flower buds and flowered in photoperiods of 8–14 h but not with 15 h or longer. The critical day length is 14 h. Eight photoinductive cycles were needed to induce flowering. Thus, the critical photoinductive cycle of S. salsa is about eight cycles. The longer the day length, the more the photoinductive cycles, and the more the number of flowers in range of eight to 13 photoinductive cycles. On the other hand, we discovered the phenomenon of flowering reversion in this experiment. Before the plants had finished their flowering induction (only exposed to photoinductive photoperiod for four to six photoinductive cycles), when they were transposed to non-photoinductive photoperiod of 16 h day-length, rather than flower organs, succulent leaves grew up from the original flower primordia. These experiments show that the halophyte S. salsa has a habit of photoperiodic response similar to those of nonhalophytes.