Index | Search | Home | Table of Contents

Raveh, E., J. Weiss, A. Nerd, and Y. Mizrahi. 1993. Pitayas (Genus Hylocereus): A new fruit crop for the Negev desert of Israel. p. 491-495. In: J. Janick and J.E. Simon (eds.), New crops. Wiley, New York.

Pitayas (Genus Hylocereus): A New Fruit Crop for the Negev Desert of Israel*

Eran Raveh, Julia Weiss, Avinoam Nerd, and Yosef Mizrahi


  1. METHODOLOGY
  2. RESULTS AND DISCUSSION
    1. Pollination
    2. Shading
  3. CONCLUSIONS
  4. REFERENCES
  5. Table 1
  6. Table 2
  7. Table 3
  8. Fig. 1
  9. Fig. 2
  10. Fig. 3
  11. Fig. 4
  12. Fig. 5
  13. Fig. 6
  14. Fig. 7

Members of the genus Hylocereus (Pitaya) (Fig. 1), Cactaceae are epiphytes which produce high-quality fruits that resemble those of the prickly pear (Opuntia ficus-indica Mill.) in appearance but differ from the prickly pear in that they contain very small seeds. Unlike the prickly pear, the peel of pitaya fruits is thornless or becomes thornless during ripening. Attempts are currently being made to domesticate species of the shrub in Central America and in Israel (Barbeau 1990; Nerd et al. 1990). Some agrotechniques methods have been developed (Barbeau 1990; Arcadio 1986), but there remains a lack of detailed information about conditions required for growth and fruit production.

Twenty three genotypes of various Hylocereus species were first introduced and propagated in our institutes nursery in 1986. The plants characteristics were studied in our greenhouse, and some genotypes were planted in four experimental orchards at various sites in the Negev Desert (Nerd et al. 1990). When the shrubs were planted in the open sun, they developed bleaching symptoms and growth was inhibited. Plants recovered only after they were shaded.

In this paper, we describe fruiting in several selected clones and the effect of shading on photosynthesis and growth in two of these clones.

METHODOLOGY

Seeds and cuttings of various Hylocereus species obtained from individuals, and botanical gardens in California, Columbia, Equador, and Israel were propagated in our nursery. In greenhouse studies, three plants of each clone were planted, and plant development, flowering and fruit set, and quality were evaluated. A shading experiment was carried out with cuttings of H. polyrhizus and Hylocereus sp. type Equador (species not yet defined) planted in 15-liter buckets filled with a nursery mixture were placed in a nethouse. Three levels of shading, 30, 60, and 90%, were provided by means of nets of different densities. Each treatment contained 16 plants of each species. Growth parameters (length and weight) were measured during the winter-spring (November-April) of 1990-1991.

RESULTS AND DISCUSSION

The species can be divided into two groups according to fruit characteristics and fruit development: those having large red fruits and short fruit development time (group Alon), and those having smaller yellow fruits and longer time of fruit development (group Katom) (Table 1, Fig. 2). Katom fruits were judged to be superior (by our team of tasters), probably because they had the highest total soluble solids content (Table 2). In general, fruits of all the species were very juicy, with a pleasant sweet-sour taste.

Pollination

Hylocereus species are described as being self-compatible, but cross-pollination by insect occurs frequently (Cacioppo 1990). We found that some species set fruit after hand-self pollination, whereas others did not (Table 3). Thus, within the genus Hylocereus, there are both self-compatible and self-incompatible species. In one species, H. sp. type Katom, we found that self-pollination occurred without a pollen vector. Hand-cross pollination between the various species led to 100% fruit set indicating no incompatibilities among these species. The flowering period of Hylocereus genus starts in mid-May and the last flowers appear in November. Flowering occurs in two or three waves. For the cultivation of self-sterile plants, we recommend that several species be planted together to guarantee the availability of cross-pollination partners. Flowers of all species were opened for only one night between two hours before dusk and three hours after dawn. Other reports claim that Hylocereus flowers are open during several nights (Cacioppo 1990; Barbeau 1990).

Shading

Maximum and minimum air temperatures fluctuated around 30° and 8°C, respectively, during the 150 days of the experiment (mid-October to mid-March), and the three parts of the nethouse exhibited similar maximum and minimum temperatures (Fig. 3). Maximum levels of photosynthetic active radiation (PAR) increased with decreasing shading (Fig. 4), i.e., the main difference among the three sections of the nethouse lay in the radiation intensity.

Growth was expressed as the relative growth rate (RGR) which is defined as: (Lt2-Lt1)/Lt1 &0198; day, where Lt1 is total stem length at time t1 and Lt2 is total stem length at time t2.

Growth of H. polyrhizus increased significantly in the winter time (November-February.) with decreasing shading. This tendency was also found less significantly for Hylocereus sp. type Equador (Fig. 5).

The fresh weight of the plants on the 150th day is shown in Fig. 6. The weight increase in H. polyrhizus was greater than that in Hylocereus sp. type Equador (fresh weight at zero time was 148±13 g SE and 60±4 g, respectively), particularly at the lowest and medium levels of shading. These findings are compatible with those for the RGR measurements, indicating that H. polyrhizus exhibits a higher tolerance to high radiation than the Equador type. The two species differed in CO2 uptake rate (Fig. 7), the rate being correlated to growth. Values of CO2 uptake at the lowest shading level were in the range found by Nobel and Hartsock (1990) for other epiphytic cacti.

CONCLUSIONS

Cultivation of Hylocereus plants in the Negev will have to be restricted to shadehouses, with the shading level being adapted to the specific species. To ensure maximum pollination, compatible clones or species will have to be planted in close proximity and pollinating insects will need to be made available in the shadehouse, perhaps by placing beehives in the shadehouse. Crossing between various species of the genus Hylocereus is feasible and could lead to improved types.

REFERENCES


*The authors would like to thank the following agencies: US-AID-CDR and the Rich Foundation for partial support of this research.
Table 1. Fruit appearance of pitayas under shade in the greenhouse in the third year.

Hylocereus species Peel color Pulp color Peel morphology
H. sp. type Alon Light red White Large scales with light green tips, fruit oblong
H. costaricensis Dark red Violet Small scales, fruit round
H. sp. type Katom Yellow White Spines, easy to remove, peel bearing warts, fruit oblong
H. paolyrhi Dark red Violet red Large scales with dark green tips, fruit oblong
H. sp. type Equador Yellow White Spines, easy to remove, peel bearing warts, fruit oblong


Table 2. Fruit quality if pitayas under shade in the greenhouse in the third yearz.

Pulp
Hylocereus species Fruit weight (g) Pulp/peel fresh weight basis DW (%) TSS (%) Reducing sugars (mg/g fw) Titratable acidity (meq/g fw) pH
H. sp. type Alon 595±32 3.7±0.4 16.4±0.8 10.9±0.5 107.2±7.8 32.3±6.9 4.9±0.02
H. costaricensis 308±15 3.1±0.4 16.2±0.8 12.2±0.8 84.6±7.3 50.6±8.9 4.7±0.02
H. sp. type Katom 96±8 1.1±0.1 20.9±0.3 16.6±2.5 93.7±13.3 23.1±3.5 4.6±0.00
H. paolyrhi 327±24 2.0±0.1 17.2±1.2 10.5±0.5 68.8±6.4 63.8±2.0 5.2±0.50
H. sp. type Equador 115±8 --- --- --- --- --- ---
zValues ±SE


Table 3. Compatibility systems of various Hylocereus speciesz.

Plant species Hand-cross pollination (% fruit set) Hand-self pollination (% fruit set) Covered, no hand pollination (% fruit set)
H. sp. type Alon100470
H. costaricensis10000
H. sp. type Katom100100100
H. paolyrhi10000
H. sp. type 10487100670
zSix to ten flowers were used for each treatment.


Fig. 1. Hylocereus paolyrhi, 3-years-old, growing on trellis system under netting, at Beer-Sheva (October 1991).


Fig. 2. Length of fruit development stage in fruits of var-ious species of the genus Hylocereus. Bars represent ±SE.

Fig. 3. Maximum and minimum air temperatures at three levels of shading.

Fig. 4. Noon PAR at three levels of shading.
Fig. 5. Relative growth rate (RGR) of H. polyrhizus (A) and Hylocereus sp. type Equador (B).


Fig. 6. Fresh weight of H. polyrhizus and Hylocereus sp. type Equador after five months in the shadehouse. Mean fresh weight of plant at planting was 148±13 g for H. polyrhizus and 60±4 g for Hylocereus sp. type Equador. Bars represent ±SE.

Fig. 7. Daily CO2 uptake of H. polyrhizus and Hylocereus sp. type Equador. Measured mid March 1991. Values are means for five plants. Bars represent ±SE.
Last update September 15, 1997 aw