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Mizrahi, Y., A. Nerd, and Y. Sitrit. 2002. New fruits for arid climates. p. 378–384. In: J. Janick and A. Whipkey (eds.), Trends in new crops and new uses. ASHS Press, Alexandria, VA.


New Fruits for Arid Climates

Yosef Mizrahi, Avinoam Nerd, and Yaron Sitrit

INTRODUCTION

In many countries around the world “developers” take the best agricultural lands for housing, and urbanization spreads rapidly. As a result, the agricultural industries are pushed into less productive lands in which the climate is not the most suitable for crops. A very good example is found in Israel. The best agricultural area is along the Mediterranean coast where the citrus industry flourished for almost a century and is the area where the famous ‘Shamouti’ (syn. Jaffa) orange was found and developed. Later, “Jaffa” became the trade name for the whole successful Israeli citrus industry. Today, most of this area is heavily populated and the agricultural industry is pushed into the Negev Desert where extreme temperatures exist, the soil is less fertile, and water, if available, is saline and/or very expensive. Labor is also less available and very expensive. The government by doing “more of the same” is encouraging the reestablishment of the citrus industry in the Negev and planting olives for oil (Negev of Growth Campaign).

Traditional crops in Israel appear to be at the end of their viable economic-life-cycle, but there is hope that new crops could establish a future profitable agricultural industry (Mizrahi and Nerd 1996). New crops could also ameliorate the increase in atmospheric CO2 concentration (greenhouse effect) which increases temperature and drought, changing fertile lands into deserts (Mizrahi and Nerd 1996). The old traditional crops cannot cope with these expected changes. Over a decade ago Noel Vietmeyer (1986, 1990) raised the point that humans are “stupid” to neglect the huge treasure-house of biodiversity available in the thousands of wild plants and neglected crops that might solve many of our present and future agricultural problems. The aim of our program that started 16 years ago was to develop totally new fruit crops not known in the world markets, as new crops for desert areas (Nerd et al. 1990, 1993; Mizrahi and Nerd 1996, 1999). After many years of extensive R&D we had both failures and successes and we wish to share our experiences with others interested in new crops.

FRUIT TREES INTRODUCTION UNDER DIFFERENT DESERT ECOZONES

Since 1984 we have introduced and tested over 45 fruit tree species. Many of them are totally wild while others are neglected crops known only in their country of origin. All these species were tested in different ecozones around our Negev Desert, each differ from the other by average and extreme high and low temperatures and salinity of the irrigation water. In Israel, climatic and socio-economical considerations dictate that almost all crops are irrigated and in the Negev desert, most areas are irrigated with saline water. Salinity differs in the various ecozones not only by degree of salinity but also by ion composition. Whenever Na+ is more abounded than Ca++ (Rengel 1992) and Cl- is more abounded than SO4--, the damage of salinity is more pronounced and more species will die even under 4dS/m2 (Nerd et al. 1990; Mizrahi and Nerd 1996).

FAILURES WITH SOME AFRICAN SPECIES

As would be expected we have had many failures. Among our unsuccessful attempts is the yehib (Cordeauxia edulis Hemsl., Caesalpiniaceae), a wild shrub from the horn of Africa. This shrub produces a tasty edible nut even under extreme drought conditions when most plants will die. Unfortunately, we found yehib to be extremely sensitive to chilling temperatures, and plants have died at 4°C (Mizrahi and Nerd 1996). This unique bush deserves much more R&D efforts to save it from extinction (Miege and Miege 1979; National Research Council 1979).

Mongongo (Ricinodendron rautanenii Schniz, Euphobiaceae) is a nut-producing wild tree from the Kalahari Desert in southern Africa. It is highly nutritious and tasty nut but the yields are very low with no hope for the Israeli horticultural industry (Biesele et al. 1979; Fox and Norwood-Young 1982; Mizrahi and Nerd 1996). In all of the tested ecozones we only established fruiting mongongo trees in the Besor region with moderate temperatures and good quality irrigation water (Nerd et al. 1990).

A species which performed very well in most tested ecozones is the African plum (Harpephyllum caffrum Bernh. ex C. Krauss, Anacardiaceae). This wild tree of Southern Africa produces many small, tasty, aromatic, red fruits in bunches with different hues. However, there are problems that inhibit cultivation. First, the fruit is very small (few grams) and hence labor intensive and second the flesh is only 10% of the total weight. However it can be used for home gardens and city and park gardening with fruits that children and others will enjoy picking.

CACTI

Of the many plant families we have explored, the Cactaceae is the most important one for Israel, since water is the major limiting factor and becomes scarcer every day. In the future, the water authorities think that only recycled water will be used for agricultural production. The high water use efficiency of the cacti stems from their Crassulacean acid metabolism (CAM) pathway (Gibson and Nobel 1986; Nobel 1994; Mizrahi et al. 1997). Cacti have many uses as crops (Mizrahi et al. 1997). Our efforts have concentrated on fruit production of the unknown pitayas and not on the well-known prickly pear now called cactus pear [Opuntia ficus-indica (L.) Miller] that is already grown world-wide (Mizrahi et al. 1997, Mondragon Jacobo 1999, 2001).

Pitaya is a common name to many genera and species of cacti, all with elongated coloumnar stems (Ortiz 1999, 2001). Most of our work was recently reviewed (Mizrahi and Nerd 1999; Nerd et al. 2002) and here we would like to concentrate on updating the data and on the take-home-lesson and consequences from dealing with “real new crops.” These crops are not well known and there is great confusion about their botanical identity. We shall describe briefly each one of the species that have made their way into the European markets.

Vine Cacti

Yellow pitaya [Selenicereus megalanthus (Schum.) Britton & Rose], is a vine cactus that needs a trellis system for support. In Israel net-houses are required to avoid photo-inhibition and bleaching of its stems (Mizrahi and Nerd 1999; Nerd et al. 2002). Colombia was the first country to sell S. megalanthus in the world market under the name “yellow pitaya.” Until now, the incorrect names of Hylocereus triangularis and Hylocereus undatus have been used to describe this plant (Weiss et al. 1995). This plant can tolerate high temperatures more than the other vine cacti, yields spiny fruits where the spines abscise easily upon ripening and are unseen by consumers (Fig. 1). The fruits are smaller than the other vine cacti fruits but the taste is superior, hence, the higher prices obtained in the markets in comparison with other vine cacti. Most of the plantations in Colombia have been uprooted due to heavy infestation with fungi (Bibliowicz and Hernandez 1998). We found that desert environment is better than tropical, both from the phytosanitary point of view and the possibility to control and regulate plant production via irrigation, fertilization, and manipulation of shade regimes (Raveh et al. 1996; Mizrahi and Nerd 1999; Nerd et al. 2002).

Fig. 1. Fruit of the real yellow pitaya—Selenicereus megalanthus. Notice the tubercles on the fruits’ peel, before ripening they contain large spines (1–2 cm), which abscise easily upon ripening.

The red pitaya [Hylocereus undatus (Haworth) Britton & Rose] is known in Latin America but the Asian name is dragon-fruit (Fig. 2). There are red flesh clones but we do not know where they are produced. Some red flesh pitayas are produced in Nicaragua and are considered Hylocereus costaricensis (Weber) Britton & Rose. In Israel we cultivate Hylocereus polyrhizus Weber. Guatemalan researchers refer to it as Hylocereus undatus (Mizrahi and Nerd 1999). Pigments differ among the clones and species, and have not been fully explored. For example the Hylocereus sp. clone 10487 has red color while the H. polyrhizus clones show glowing purple, a unique color, which has been chemically identified as hylocerenin and iso-hylocerenin (Wybraniec et al. 2001). The major problem which exists in these plants in desert areas is their sensitivity both to low and high temperatures (Mizrahi and Nerd 1999). Since variability in these characteristics exist among genotypes, and since there is no genetic barrier among species and even genera, breeding may solve these problems (Lichtenzveig et al. 2000; Tel-Zur et al. 2001). Other important problems with these fruits which might be solved with breeding, is the bland taste and lack of distinct flavor. Sellers of these fruits in Europe claim that the dragon fruit and other red pitayas, which exist today in the market, are bought for their beauty and used mainly for decoration (A. Ronen unpubl. information). Our first hybrids released lately to our growers, exhibit much better taste than the original clones. However there is a lack of effort for breeding tolerance to extreme desert conditions, because of what we consider to be “establishment antagonism.” We are convinced that in addition to marketing issues genetic and physiological R&D efforts are required to convert these exotics to mainstream commodities in the world markets.

Fig. 2. Fruit of red pitaya (Dragon fruit in Asia) Hylocereus undatus. Note that the fruit contains scales that shrivel post harvest, and they are the main reason for loss of fruit value.

Columnar Cacti

Among the various columnar cacti we believe that the most promising one is Cereus peruvianus Britton and Rose, which might be the same species as the Cereus jamacaru (Nerd et al. 1993; Mizrahi and Nerd 1999; Gutman et al. 2001). The plant is columnar with many branches (Fig. 3). Columns may bear spines to various degrees and length, but the fruits are smooth and totally spineless. The fruits are medium in size, and vary in skin color from yellow to red with various hues. Flesh is white and aromatic with a delicate sour/sweet taste. Black seeds are embedded in the flesh, but are soft and edible reminiscent of kiwifruit seeds (Fig. 4). Israel was the first country to sell this fruit both in the domestic market and in Europe (Fig. 5). Efforts have been carried out in the US and Australia to introduce this unique fruit to their markets. This plant might have other industrial uses because of polysaccharides which may be extracted from its stems (Alvarez et al. 1992). Stem pruning is necessary to ensure efficient fruit harvest. Our results in domestication of this fruit was recently reviewed (Mizrahi and Nerd 1999; Nerd et al. 2002) and here we would like to discuss difficulties in marketing which might hamper introduction. In Israel there are only a few producers. One producer is marketing the fruit at the proper stage of ripeness, with each package containing a leaflet describing the fruit, how to use it fresh, its other uses, storage and nutritional information. However, others sell it in simple boxes with other fruits, at various stages of ripening, from unripe, to ripe and over-ripe, without explanatory leaflets, acts which damage the future of this newly developed fruit. In Europe columnar cactus fruit was accepted quite well but supermarket chains required 300 tonnes/year, while the quantities produced in Israel in 2001 were only 70 tonnes. Special efforts are required from the exporters to sell it in small quantities and if they are not determined to market this fruit it will not be sold. The Israeli establishment (as other establishments) is not interested in new crops. Despite these difficulties, we foresee a great future for this crop due to early and precocious yields (Fig. 6), beautiful appearance, excellent delicate taste, long shelf-life to enable export, and, above all, minimum demand for irrigation and water-stress tolerance.

Fig. 3. Five years old Cereus peruvianus plant, multi branched + fruits. The picture was taken at Sde Nitzan in the Western Israeli Negev Desert.
Fig. 4. Cereus peruvianus cut fruit. Note the smooth peel and the many black, soft edible seeds embedded in the pulp.
Fig. 5. Export box of Cereus peruvianus ripe fruits, ready to be shipped to Europe. The trade name Koubo is used by AGREXCO the main Israeli export company.
Fig. 6. Heavy load of fruits on 4 years old Cereus peruvianus plant. The picture was taken at Sde Nitzan in the Western Israeli Negev Desert.

OTHER FRUIT TREES SUITABLE FOR DESERT AREAS

Of the many fruit trees we have tested the following species are ready for the first trials to test their feasibility as new orchard crops under desert conditions. We have selected clones where we had information on tolerance to desert conditions, fruit yields, quality, and shelf life (Mizrahi and Nerd 1996). These fruits include white sapote (Casimiroa edulis Llave & Lex, Rutaceae) (Nerd et al 1992); black sapote (Diospyros digyna Jacq., Ebenaceae); desert apple ber or bor in India (Ziziphus mauritiana Lam., Rhamnaceae); marula from Southern Africa [Sclerocarya birrea (A. Rich) Hochst. sbsp. caffra (Sond.) Kokwaro, Anacardiaceae] (Weinert et al. 1990; Nerd and Mizrahi 2000); argan [Argania spinosa L. (Skeels), Sapotaceae], wild tree of Morocco, the best culinary oil is extracted from its seeds (Prendergast and Walker 1992; Nerd et al. 1994); and sapodilla [Manilkara zapota (L.) van Royen, Sapotaceae], from South East Asia, which is already a crop in many warm countries (Morton 1987). Some of these species (pitaya, white and black sapotes, and sapodilla) are also recommended for tropical zones such as Northern Queensland in Australia (Finocchiaro 2001). Unfortunately there is a lack of support to develop these and other new crops and farmers are afraid to take the risks. The daring farmers of Israel are already involved in production of various pitayas.

Another interesting fruit, which has not reached the R&D stage, is the monkey orange. It consists of three main species as follows: Strychnos cocculoides Backer; S. spinosa Lam.; and S. pungens Solereder, Loganiaceae, all native to Southern Africa (Wehmeyer 1966; Fox and Norwood-Young 1982; Taylor 1986). Strychnos pungens did not survive in any of our introduction orchards. Strychnos cocculoides which is considered the best of the three (in terms of eating quality), survived only in the Besor region (good quality water and moderate temperatures) and some trees started to bear fruits not of very high quality. It is too early to judge its performance. So far the best of the three under our conditions is S. spinosa. It survived in three of our introduction orchards and performed very well in the Besor area (Fig. 7). We have around 15 fruiting trees with high variability for growth, yields, fruit size, ripening season, and taste. Some of the seedlings bear astringent, bitter fruits, other bear very sour ones but two of the trees bear excellent tasty fruits. In organoleptic taste tests, people were requested to compare the monkey orange fruit with familiar fruits; the most common answers were, orange, banana, and apricot, and all possible combinations among them. The fruits emit a delicate aroma reminiscent of the spice clove. GC/MS analysis performed by Ephraim Lewinson of Newe Ya’ar, (ARO Israel) found eugenol, the essential oil found in clove (unpubl. results). Over 90% of the panel claimed that it was very tasty. Various products such as juices and dry fruit rolls are potential uses for this fruit. The fruit is large (400–1200 g), (Fig. 8), round, has a thick shell 4–7 mm, and contains 30%–45% juicy flesh with over 20% total soluble solids, and high acidity (over 200 µeq H+/gFW).

Fig. 7. Six years old tree of monkey orange Strychnos spinosa bearing fruits. The picture was taken in the Besor Research Farm, in the Western Israeli Negev Desert.
Fig. 8. Open fruit of monkey orange Strychnos spinosa. Note the very thick peel.

We are aware of the difficulties in introducing a new product into a market which is full of other temperate and tropical fruits. The first questions we are asked is—who needs these strange fruits? Who is going to buy them? For how much? What is the volume that the market can receive? All these are legitimate questions, which are discouraging for the establishment to deal with. On the other hand it is quite clear that apples and citrus fruits will struggle to withstand the changing economic and climatic conditions (Vietmeyer 1990). Also it is known that among the affluent class in the Western societies there is an increasing demand for exotic fruits and vegetables and some such as kiwifruit have become mainstream products (Anon. 2000).

The health profile of these new fruits is unknown and needs to be explored. For example the non-proteinecious amino acid, taurine was found in Opuntia ficus-indica, in spite of the common belief that the main source of taurine in our diet, comes from animals especially sea-food (Stitzing et al. 1999). Taurine is an important ingredient in the so called “energy drinks” with proven positive activity on human well-being (Seidl et al. 2000). In spite of all these arguments, exotic new fruit trees have received strong antagonism from all possible established organizations, such as the officials in the Ministry of Agriculture, Associations of Fruit Growers, and the main Export Company AGREXCO. We conclude with a plea from a report which speaks for itself.

"Every production system and every mature organization is equipped with antibodies against deviations from routine. These antibodies work overtime to kill all interest in the new product and are very likely to succeed. It is an innate property of every established industrial organization, which is why most new products are created and brought to market by young organizations that have no standard products to occupy them. Established organizations (Israeli agriculture among them) that want to get into this business of introducing new products have to build themselves managerial mechanisms designed to act as a countervailing weight against the forces of routine."

Yshai Sfarim (1989)

REFERENCES