Pitayas (Genus Hylocereus): A New Fruit Crop for the Negev Desert of Israel* Eran Raveh, Julia Weiss, Avinoam Nerd, and Yosef Mizrahi

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.

Growth was expressed as the relative growth rate (RGR) which is defined as: (Lt 2 -Lt 1 )/Lt 1 &0198; day, where Lt 1 is total stem length at time t 1 and Lt 2 is total stem length at time t 2 .

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 CO 2 uptake rate (Fig. 7), the rate being correlated to growth. Values of CO 2 uptake at the lowest shading level were in the range found by Nobel and Hartsock (1990) for other epiphytic cacti.

Arcadio Luis, B. 1986. Cultivo de la Pitaya. Federacion Nacional de Cafeteros. Bogota, D.E. p. 1-18.

Barbeau, G. 1990. La pitahaya rouge, an nouveau fruit exotique. Fruits 45:141-147.

Cacioppo, O.G. 1990. Pitaya: una de las mejores frutus producida por Colombia. Inforamtive Agro Economico. Feb. p. 15-19.

Nerd, A., J.A. Aronson, and Y. Mizrahi. 1990. Introduction and domestication of rare and wild fruit and nut trees for desert areas, p. 353-363. In: J. Janick and J.E. Simon (eds.). Advances in new crops. Timber Press, Portland, OR.

Nobel, P.S. and L. Hartsock. 1990. Diel patterns of CO2 exchange for epiphytic cacti differing in succulence. Physiologia Plant. 78:628-634.

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

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 --- --- --- --- --- ---

Plant species Hand-cross pollination (% fruit set) Hand-self pollination (% fruit set) Covered, no hand pollination (% fruit set) H. sp. type Alon 100 47 0 H. costaricensis 100 0 0 H. sp. type Katom 100 100 100 H. paolyrhi 100 0 0 H. sp. type 10487 100 67 0

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.