Journal of Fruit and Ornamental Plant Research Vol. 12, 2004: 127•136 INTRODUCING AND GROWING SOME FRUITING COLUMNAR CACTI IN A NEW ARID ENVIRONMENT Ahmed A. ElObeidy Department of Fruit Horticulture, Faculty of Agriculture Cairo University, Giza, EGYPT e•mail: [email protected] (Received January 23, 2004/Accepted August 11, 2004) ABSTRACT One of the most important ways of coping with increasingly frequent water shortages is improving the efficiency of water use. Planting drought•resistant crops is a promising way of reducing the demand for water. Columnar cacti are especially drought•tolerant and highly productive even though they consume very little water. In the United Arab Emirates, seven columnar fruiting cacti were evaluated in terms of their capacity for vegetative growth in a new arid environment. The cacti evaluated were: Carnegiea gigantea, Myrtillocactus geometrizans, Pachycereus pecten• aboriginum, P. pringlii, Stenocereus griseus, S. stellatus and S. thurberi. Plants were propagated from cuttings in a greenhouse. Roots developed within two to four weeks of planting. The plants were acclimatized and transplanted in an orchard in the desert. Although the cacti varied widely in terms of growth, most of them are promising species for cultivation in desert environments. Keywords: arid environment, cactus, fruits, new crops, water use efficiency INTRODUCTION major step in coping with imminent water shortages is the formulation and One•third of the world's popu• implementation of a comprehensive lation faces water shortages, and this water management plan that reduces is expected to rise to two•thirds by the the imbalance between supply and year 2025 (U.N. Report, 2000). demands. A well•designed plan will Government•sponsored investments focus primarily on wise water mana• have increased urban landscaping and gement and on curbing rising demand agriculture activities, which has resul• (Rogers, 1994). ted in severe over•use of water There is a growing need for new resources beyond the natural renewal approaches to water management in capacity (Wilhite, 2000). The first arid and semi•arid environments, as A.A. ElObeidy were as in other environments were smaller cacti with more segments. rainfall is unreliable. A search for Cactus spines create a microclimate highly productive, drought•resistant around the stem, which is covered fruit crops is underway to address the with a waxy cuticle. needs of farmers living in drought• Among the adaptations which prone areas. enable cacti to tolerate harsh con• Columnar cacti are among the ditions are: a stem capable of storing drought resistant plants under consi• water; the reduction or absence of deration. Many columnar cacti leaves; a waxy cuticle (Sowell, 2001); produce unique fruits which can be opening of the tissues during the eaten fresh or dried, or be processed night to facilitate the uptake of into juice. Some cacti promise to be carbon dioxide; and Crassulacean profitable commercial crops (Casas Acid Metabolism (CAM) (Malda et et al., 1997). al., 1999). Two cactus structures, ribs The Cactaceae are a large family and tubercles, enable the stem to of succulents whose natural range is expand and contract in response to almost entirely restricted to the New changes in water availability. Cactus World (Anderson, 2001). They have roots are usually shallow and non• evolved physiological and morpho• succulent, and require little water. logical adaptations which enable When the soil dries, the fine lateral them to grow in habitats far too dry roots generally die, while the larger for other plants (Mauseth, 2000). roots become covered with a corky They also tolerate high temperatures layer (periderm) (Sowell, 2001). Water and poor soils, which makes them conductivity in the roots decreases highly adaptable to new environ• dramatically during soil drying, which ments. Cacti can grow in dry, infertile reduces water loss from the plant marginal land where common crops tissues to the soil (Huang and Nobel, cannot grow. As succulents, cacti can 1994; Nobel and Cui, 1992). survive long periods of drought by The aim of this study was to living off water stored in their tissues. evaluate the capacity of seven species Water taken up into the stem is of fruiting columnar cacti for vege• incorporated in a mucilaginous sub• tative growth in a new arid environ• stance that does not evaporate as ment in Al•Oha, United Arab Emirates. readily as water (Saag et al., 1975). Cacti are not only resistant to MATERIAL AND METHODS desiccation, but are also extremely Plant material and propagation tolerant of desiccation when it occurs (Sowell, 2001). However, they are Cacti can be propagated either extremely susceptible to root rot from seed or cuttings (Lopez•Gomez et when they are grown in waterlogged al., 2000). Asexual propagation soil. Large columnar cacti consisting produces daughter plants which are of only a few cylinders transpire less genetically identical to the parent plant. and are more drought resistant than This allows a superior genotype to be 128 J. Fruit Ornam. Plant Res. vol.12, 2004: 127•136 Growing some fruiting columnar cacti in a new arid environment perpetuated without losing any desir• The cacti were carefully slipped able traits (ElObeidy, 2001). out of the flowerpots and planted in Cuttings of seven fruiting cacti holes which were about 15 cm wider were obtained from private nurseries and a few centimeters deeper than in Brazil, Mexico and the United the flowerpots. Heavy gloves and 30 States. The cacti evaluated were: cm forceps were used to avoid Carnegiea gigantea, Myrtillocactus injuring the technicians and plants. geometrizans, Pachycereus pecten• The soil was lightly firmed around aboriginum, P. pringlii, Stenocereus the plants. The plants were then griseus, S. stellatus and S. thurberi. watered thoroughly. The cuttings were allowed to dry A drip irrigation system was used in a warm, dry area for ten days to in the orchard. Fertilizer (12:4:24) was permit the cut surface to heal and applied one month after transplanting, develop callus. The callus helps and once a month after that. prevent rotting when the cutting is placed in a rooting material. The larger Data analysis the cutting, the longer it should be Data were collected in two dried. successive seasons (2001/2002 and After drying, each cutting was 2002/2003). The data recorded placed in the center of a 60 cm included: percentage of surviving flowerpot one•third filled with a pot• plants; growth rate (stem length and ting mix of one part peat and two parts diameter); number of ribs; number, soil. The flowerpots were then filled to length and distribution of spines; and the two•thirds level with the same root development. Other observations potting mix and kept in a green• on growth behavior were also house. recorded. Thirty plants of each species were evaluated. Thirty more plants of Orchard and transplantation Pachycereus pecten•aboriginum were The orchard used in this study evaluated to determine the effect of was located in the Al•Oha area, planting time on growth and United Arab Emirates. The soil is development (Tab. 2). sandy and has a salinity of 2200 ppm. Means were compared using The chief salt in the soil is sodium Duncan’s multiple range t•test at chloride. An underground aquifer is P = 0.05. the only source of irrigation water, which has a salinity of up to 2800 RESULTS AND DISCUSSION ppm. Local temperatures can reach 49°C during the summer. The average Seven species of columnar fruiting annual rainfall is 77 mm. cacti were evaluated in terms of their In the autumn, plants were taken capacity for vegetative growth in out of the greenhouse, acclimated for a new arid environment in Al•Oha, ten days in the shade, and planted in United Arab Emirates. the orchard. J. Fruit Ornam. Plant Res. vol.12, 2004: 127•136 129 A.A. ElObeidy Most of the cacti adapted well to 0.8 cm/month in diameter. Each the new environment. In the local areole consisted of fourteen 1.0 to climate, the growing season lasted 3.0 cm long spines, one to three of from the middle of September until which were central spines. All the middle of June. No growth or spines on the new growth were red development was observed during and turned white with age. the hot summer months. Pachycereus pecten•aboriginum After being planted in the had stems which had eight to ten ribs orchard, Myrtillocactus geometrizans and which grew 3.9 cm/month in showed yellowing in response to height and 0.7 cm/month in diameter. stress. The stems were blue•green Spines on the new growth were bright with four to six ribs, and grew 3.3 reddish•brown and turned white with cm/month in height and 0.7 cm/month age (Fig. 4). Each areole consisted of in diameter (Tab. 1). Numerous up• one 3.3 cm long central spine curving branches began to develop surrounded seven or eight 1.0 cm a month after transplanting (Fig. 1 and long peripheral spines. Tab. 3). Each areole consisted of Neither species of Pachycereus a 3.0 cm long central spine surrounded developed branches or sprouts during by five 1.0 to 1.5 cm long peripheral the first two seasons. However, in spines. New spines were reddish, and their natural habitat, Pachycereus old spines were lead•colored. On the species develop erect branches close older parts of the stem, the spines to the ground which grow almost had fallen off and smaller, 0.1 to straight up. The branches are almost 0.3 cm long spines had developed in as big as the main stem (Anderson, their place. 2001). Native to Central Mexico and Both species of Pachycereus Guatemala, M. geometrizans produ• produce edible fruits with sweet, ces berry•like fruits in large numbers juicy, pink or red flesh and small along the rib edges.