The 2012 ASHS Annual Conference

Long overlooked outside its native range in Central America, the dragonfruit (Hylocereus sp.) has become an increasingly popular specialty fruit item in markets spanning the globe from Asia to Europe.  In the last ten years the United States has joined in the excitement generated by this vining-type cactus, known for its striking fruit color and its large nocturnal inflorescences, with small commercial plantings having been established in both California and South Florida.  Currently limitations to expanded commercial production are due to a lack of cultivars with improved flavor, a relatively small pool of flesh and floral colors, and need to develop additional self-fertile varieties.  To overcome these limitations, the objectives of this project were to develop new hybrids of dragonfruit and a system for their clonal propagation using in vitro tissue culture techniques. This will enable the rapid introduction of plant material when new selections are ultimately made.  Selections of H. guatamalensis and H. stenoptera where chosen for their differing flesh and flower colors, and hybrids were created by reciprocal crosses between them.  The resulting fruit were harvested, and the seeds removed, cleaned and sterilized, before establishing in vitro for germination.  Seeds were placed in magenta G7 boxes containing MS medium, 5 per box, for a total of 50 seedlings per cross.  For each cross, five seedlings displaying the greatest hybrid vigor were chosen to represent individual lines after attaining a minimum shoot length of 6 cm. Shoots from these selections were then dissected into 3–4 mm sections containing at least one node and placed 3 per box in MS medium modified with different combinations of 1-Naphthaleneacetic acid (NAA) and thidiazuron (TDZ), representing 8 treatments, with 6 boxes per treatment.  Cultures were monitored weekly for growth and evaluated for percentage of explants per treatment showing shoot formation, root formation, and number of shoots and roots per explant.  Shoot formation was observed for all treatments, including the control, however the best results for multiple shoot formation were achieved with a combination of NAA (0.05 μm) + TDZ (0.5 μm), TDZ (2.27 μm), and NAA (0.05 μm) + TDZ (2.27 μm).  Plantlets were regenerated and transferred to greenhouse.  In the present study we demonstrated a feasible technique for the clonal propagation of hybrid dragonfruit.  Additional studies should evaluate the field performance of hybrids, fruit yield, visual appearance of flesh and flower colors, °Brix levels, and the ability to self-pollinate.

Abstracts:

• Dragonfruit.jpg (70.2KB) - Abstract Text