Red pitaya (Hylocereus 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.

Bougainvillea (Bougainvillea spectabilis), native to Amazonian rainforests in South America, is an important ornamental and landscaping plant that is widely distributed in tropical and subtropical areas. A new virus disease, Bougainvillea chlorotic vein-banding, caused by a Badnavirus, Bougainvillea spectabilis chlorotic vein-banding virus (BsCVBV), was first reported in Brazil in 2001 (1) and recently discovered in Taiwan. Infected bougainvillea developed symptoms such as mottling, chlorosis, vein-banding, and stunting. Severe leaf-distortion symptoms were observed in the susceptible hybrid Taipei Red, the most popular bougainvillea cultivar in Taiwan. In electron microscopic observations, typical bacilliform virions measuring 28 × 130 to 150 nm were observed in infected bougainvillea cells. In addition, our transmission tests demonstrated that the virus could be easily transmitted among different bougainvillea cultivars by bud grafting but not by mechanical inoculation. Bougainvillea plants showed apparent symptoms 1 month after grafting. For molecular identification, viral DNA was extracted from the test plants (2), and polymerase chain reaction (PCR) was performed using the primers selected from the DNA sequences of ORF III of Sugarcane bacilliform virus (GenBank Accession No. M89923). The sequence of the forward primer was 5′-TCA AAG TTT GAT TTG AAG AGC GGG-3′ and the sequence of the reverse primer was 5′-CTT GCA TAC TGC TCC CCA TCC-3′ The primers amplified a 676-bp PCR product (GenBank Accession No. DQ103759). Nucleotide and deduced amino acid sequences were 82 and 90% identical, respectively, to the corresponding region of the Brazilian strain of BsCVBV (GenBank Accession No. AY532653). These data indicate that the bougainvillea disease occurring in Taiwan is caused by a strain of BsCVBV. Reference: (1) C. M. Chagas et al. Virus Rev. Res. 6:153, 2001. (2) H.-J. Su et al. J. Phytopathol. 151:290, 2003.

Off-season flowering in red pitaya (Hylocereus sp.), a long-day plant, can be achieved using night-breaking (NB) treatment. Among the stages of bud development, stage 0 referred to induced but not yet differentiate any bracteole and stage 3 was the stage right before emerging floral buds and the bracteole differentiation was completed. Unlike floral bud emergence, bracteole differentiation was independent of the daylength and strongly influenced by the environmental temperature. The buds of higher stages were more effective in response to NB treatment and more sensitive to chilling injury (CI). Consequently, off-season flowers in autumn and winter trials were derived mainly from stage 2 and 3 buds and from stage 0 and 1 buds, respectively. In southern Taiwan, low night temperature between 10 Jan. and 7 Feb. 2011 may be the major factor, which delay bud development in off-season production. Therefore, we conducted a heating experiment in winter off-season production to proof our hypothesis and concluded that NB treatment should be applied along with night temperature elevation or after mid-February when the minimum night temperature is increasing.