Seasonal response of night-breaking on floral bud formation in red pitaya (Hylocereus sp.) in a noninductive period

Abstract

Off-season flowering in red pitaya (Hylocereus sp.) can be achieved by night-breaking (NB) with artificial light in a noninductive season. To ensure abundant flowering, 4–6 h of NB is applied and often resulted in over flowering. This study compared the effects of four NB durations (4 h [2200–0200HR], 2 h [2300–0100HR], 1 h [2330–0030HR], and 0.5 h [2345–0015HR]) on floral bud formation in late autumn and early spring. In late autumn, the accumulated number of flowering shoots (FStotal) increased as the NB duration increased and 0.5 h was not sufficient to force 50 % of shoots flowering. The number of days to 50 % of the shoots flowering (FS50 %) was 35 for 1−4 h NB duration treatments. In late spring, the shoots were more responsive to the NB treatment and the duration effect on FStotal was less distinct; however, days to FS50 % decreased as the NB duration increased, and the shortest was 28 days in the 4-h treatment. Therefore, for obtaining shortest days to FS50 %, we suggest that the NB duration in late autumn and early spring should be 1 and 4 h, respectively. Thinning out the new sprouting are also in off-season production in early spring.