The Photoperiod-regulated Bud Formation of Red Pitaya (Hylocereus sp.)

Abstract

<jats:p>Red pitaya (<jats:italic>Hylocereus</jats:italic> sp.), which flowers between May and October and sprouts between November and May in Taiwan, has been confirmed to be a long-day plant. The areoles on the old shoots may be induced to flower after the March equinox naturally, and the floral bud formation occurs in two to three waves from May to October. We conducted experiments on photoperiodic regulation of floral bud formation from June to Dec. 2009 and tested the feasibility of off-season production in 2011. Shortening summer daylength to 8 h inhibited the areoles at the distal end of the shoots to develop into floral buds and promoted sprouting at the proximal ends of the shoots. Night-breaking treatment between the September equinox and the winter solstice led to floral bud formation. The critical daylength seemed to be ≈12 h, and night-breaking treatment would be applicable between the September and the next March equinoxes to produce off-season crops. The duration of night-breaking required for flower differentiation was longer in the cooler than in the warmer season. Four weeks of night-breaking treatment was sufficient to promote flowering in late fall (mid-October to mid-November), but 3 months were required to generate similar result in the winter and early spring (January to March) in southern Taiwan.</jats:p>

Net Houses Effects on Microclimate, Production, and Plant Protection of White-fleshed Pitaya

“…5). In September, the critical daylength was shorter than the 12-h period required for floral bud differentiation (Jiang et al, 2012). The decrease in August may be due to the period of heavy flowering and fruit bearing.…”

“…Cladodes aged 2 to 3 years, which had robust developmental status and possessed areoles capable of outgrowth, were labeled as noncurrent-year cladodes. No cladodes older than 3-years-old were retained in the plant because they have been thinned out by farmer after harvest due to lower light interception for photosynthesis inside the canopy and the number of areoles per cladode to produce flower buds had almost been exhausted (Chen, 2017;Jiang et al, 2012). Thus, two types of cladodes were labeled: current-year and noncurrent-year cladodes.…”

“…Notably, pitaya may sometimes-but not always-flower two times (waves) on a cladode during the natural reproductive period (Chen, 2017;Jiang et al, 2012); therefore, those accumulative flowering percentage values exceeding 100% indicate that there were two flowering waves on a cladode during the experimental period.…”

“…The fruit setting was almost 100% after flowering because of complete self-compatibility in white-fleshed pitaya cultivar VN White; therefore, fruit yield has never been a problem during the natural reproductive period in Taiwan (Chen, 2017;Jiang et al, 2012). To ensure fruit quality, flower/fruit thinning was made by hand and only one flower/fruit was left on each cladode in each wave in accordance with standard cultivation practices in Taiwan (Chen, 2017).…”

“…The white-fleshed pitaya 'VN White' is one of the major cultivars in southeastern Vietnam and Taiwan (Chiu et al, 2015;Food and Fertilizer Technology Center, 2018). Pitaya is regarded as a long-day plant (Jiang et al, 2012), and thus, in southern Taiwan, the natural reproductive period for white-fleshed pitaya is from summer until fall, with the first flowering typically in early May and the last in late September (Chiu et al, 2015;Hsu, 2004).…”