curred in The Netherlands, Germany, als, as well as shrubs and shrublets. Over History and England and France. This breeding 200 Pelargonium species are native to Culture of Regal activity occurred after the introduc- South Africa (van der Walt, 1993). Eigh- tion of the hooded-leaf pelargonium teen species occur in the rest of Africa, Pelargonium (P. cucullatum), which is thought to and eight on Australasia; there are also be the primary progenitor of regals two on Madagascar, two in the Near (Bailey, 1901; Clifford, 1970; van der East, and one each on the islands of St. Marietta M. Loehrlein1 and Walt and Ward-Hilhorst, 1977), to Helena and Tristan de Cunha (van der Europe from South Africa in 1690. The Walt, 1993). Richard Craig2 most complete records of these hybrid- izations are documented in the five Origin volumes of Sweet’s Geraniaceae (Sweet, Regals do not occur in the wild, ADDITIONAL INDEX WORDS. martha 1820–26). but are only known in cultivation. As washington geranium, Pelargonium The regal pelargonium has been many as nine species (see Genetics and ×domesticum referred to as the regal as early as the Cultivar Development section) have 1870s. They were also called royal pel- been identified as possible contributors argoniums in the late 1800s. Clifford to the development of the regal. All nine egal pelargoniums (Pelar- (1970) reports that a cultivar Royal or are indigenous to South Africa, and are gonium ×domesticum) are Regal was available in 1833. In the found primarily in the western and south- R one of the lesser-known rela- 1830s regals were called pelargoniums, western coastal regions and near the tives of the ever-popular zonal gera- and thus were distinguished from the Cape of Good Hope (Riley, 1963). The nium (P. ×hortorum). Other relatives other cultivated plants of the genus, primary progenitor is thought to be the of both the regals and zonals are the ivy which were referred to as geraniums. In hooded-leaf pelargonium, originally geraniums (P. peltatum) and the North America, regals were commonly described as Geranium cucullatum by scented geraniums (Pelargonium sp.). named martha washington or lady Linnaeus in 1753. The hooded-leaf All the geraniums mentioned here are washington geranium, show-, fancy-, or pelargonium is indigenous to the coastal actually pelargoniums, and all have pansy-flowered geranium, and summer region of the southwestern cape of South their origins in South Africa. Regals azalea (Liberty Hyde Bailey Hortorium, Africa. An illustration of a plant identi- are not as well known as zonals, per- 1976). In Germany, regals were re- fied as G. cucullatum was included in a haps because of their poorer garden ferred to as edelpelargonien (German catalogue published in 1687. The pub- performance, yet they have persisted edel = royal), while in Belgium in the lisher, Paul Hermann, included 10 ge- in the commercial trade for centuries. 1880s they were called Pelargonium raniums (later classified as Pelargonium) This is a tribute, primarily, to their grandiflorum. Species names which were which had been introduced from the splendid flowers (Fig. 1). For centu- unsubstantiated by taxonomic descrip- cape of South Africa. All ten were grown ries regals have been a much-admired, tions, and therefore did not gain wide in the Leyden Botanic Garden in Hol- if difficult to produce, potted plant usage, include P. ×hortulanorum, by land (Webb, 1984). The hooded-leaf with outstanding flowers. Their story Victor Lemoine in France, and the En- pelargonium was introduced to Kew begins with the Dutch trade in South glish P. speciosum (Clifford, 1970). Gardens in England in 1690 by Bentick Africa and travels around the globe and into the modern day realms of Botanical classification molecular research. The Family Geraniaceae, a mem- ber of the Order Geraniales, Subclass Nomenclature Rosidae (Cronquist, 1988), is comprised Bailey (1901) first definitively de- of five genera and 700 species (van der scribed the complex hybrid group of Walt, 1979). Genera in this family are cultivated plants known as regals. Cul- united most notably by the beak-like tivars within this group resulted from capsular fruit. The largest genera (also interspecific hybridization that oc- the first ones identified) are Geranium, Erodium, and Pelargonium. Thus the Department of Agriculture, Western Illinois Univer- respective common names refer to the sity, Macomb, IL. 61455. fruit shape: cranesbill (Greek geranos = This work was supported in part by funding from the crane), storksbill (Greek erodios = stork), Fred C. Gloeckner Foundation and the Pennsylvania State University Intercollege Graduate Program in and heronsbill (Greek pelargos = heron). Genetics. From a dissertation submitted by M.M. The two other cultivated Geraniaceae Loehrlein in partial fulfillment for the Ph.D. degree in are Sarcocaulon and Monsonia (Liberty genetics. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal Hyde Bailey Hortorium, 1976). regulations, this paper therefore must be hereby marked The feature which distinguishes advertisement solely to indicate this fact. Pelargonium, with 250 species, from 1Current address: Assistant professor of horticulture, the other genera is the presence of a spur Department of Agriculture, Western Illinois Univer- sity, Macomb, IL 61455. which is fused to the petiole and the Fig. 1. Regals are known for their outstand- 2J. Franklin Styer Professor of Horticultural Botany, uppermost sepal (Cronquist, 1988). ing floral display. (‘Aristo Cherry’ photo Department of Horticulture, The Pennsylvania State Pelargonium is comprised of herba- courtesy of Elsner PAC Jungpflanzen, University, University Park, Pa. 16802. ceous annuals, perennials and bienni- Dresden, Germany). (van der Walt and Ward-Hilhorst, 1977). 3,5-diglucosides and 3-glucoside-5- tion in England since 1786 (Harvey, Harvey (1860) reports its cultivation as (6-acetyl)glucosides of pelargonidin, 1860). an ornamental hedgerow plant, making cyanidin, peonidin, delphinidin, Other species that may have con- it the first pelargonium on record to be petunidin, and malvidin. Pigment varia- tributed to the genetic composition of used in this manner (van der Walt and tion in the petals was due to types and regal cultivars are the rose-scented pel- Ward-Hilhorst, 1977). levels of the anthocyanins present. Where argonium (P. capitatum), the heart- inner petals had more intense pigmen- leaved pelargonium (P. cordifolium), Anatomy tation (blotches), the level of pigmenta- and the celandine-leaved pelargonium In cultivation regals are used as a tion was 5 to 10 times that of the outer, (Clifford, 1970); the apricot geranium short-lived flowering potted plant. Un- less intense portion of the petal (Mitch- (P. scabrum), the rose geranium (P. der cool, frost-free environmental con- ell et al., 1998). Anthocyanins in the graveolens) (Knicely and Walker, 1966); ditions it can grow into a large, shrubby, inner petals in these cases were pre- and P. angulosum (Bailey, 1901; Jack- semi-woody plant. Leaves are usually dominantly delphinidin, petunidin and son, 1977; Langton and Runger, 1985; simple, alternate, petiolate, obscurely malvidin. Riley, 1963). Pelargonium angulosum, lobed or denticulate, but may be pal- REPRODUCTIVE ORGANS. The sometimes referred to as the maple-leaf mate and divided. Various sizes and androecium of regals consists of five to geranium (P. acerifolium) has more re- shapes of trichomes are present. Leaves, seven stamens with filaments united at cently been assigned as P. cucullatum as well as inflorescences are subtended the base. Both genotype and environ- subspecies strigifolium (Volschenk et by stipules. mental conditions can affect pollen fer- al., 1982). Walters (1985) used the FLOWERS. The zygormorphic flow- tility. Some genotypes consistently pro- orange geranium (P. citrosum), the ers are borne in a compound umbel. duce sterile stamens, while others may lemon geranium (P. crispum) and the Flowers, measuring 1.2 to 2.4 inches (3 produce sterile stamens when tempera- oak-leaved geranium (P. quercifolium) to 6 cm) across, are perfect and com- tures are too warm or irradiance is too in development of the Romany, Royal plete. The flower bud is usually enclosed low. (sold as royalty series in the United by five sepals. Flowers commonly have The gynoecium is a compound States) and Tudor regals in the late five petals, with the upper two occasion- pistil having a five-lobed stigma, fused 1900s in England. ally larger than the lower three. While nectar tubes, and five united carpels According to van der Walt’s classi- six, seven, or eight petals are not un- with five locules. Each locule contains fication (1993), the section Pelargo- common, the superfluous petals lay flat, two tandem ovules, at least one of which nium, sometimes erroneously called so that a doubling effect is absent. Petals is sterile. Placentation is exile and the Pelargium (van der Walt and Vorster, may be ruffled and often have ovary is superior. Each seed is contained 1981), includes the birch-leaf pelargo- dark-pigmented blotches or feathering, in a papery mericarp that is attached to nium, the rose-scented geranium, the especially along the veins, which may be the style along its length. Fruit capsules lemon-scented geranium, the heart- found on either the upper, the lower, or contain five mericarps and are usually leaved pelargonium, the hooded-leaf all petals. Many cultivars have bicolored one-seeded. When seeds are ripe and geranium, and the rose geranium. The flowers in which the upper two petals fruit begins to dehisce, the mericarp large-flowered geranium (syn. P. are of a different color or hue than the recurves spirally from the base while saniculaefolium) belongs to the section lower petals. adhering to the tip of the style. The Glaucophyllum (van der Walt and Ward- Regal flowers are known for their inside surface of the mericarp is plu- Hilhorst, 1977) and the celandine- vivid coloration. Colors range from white mose, allowing easy wind dispersal. leaved geranium belongs to the section to pale pink, bright crimson, mauve, Polyactium. The designated lectotype deep burgundy, purple, and lavender. Genetics and cultivar for the genus Pelargonium is the hooded- True red is a rare, but not unknown development leaf pelargonium (van der Walt and color in the regal pelargonium. Authors GENETICS. The hooded-leaf pelar- Vorster, 1981). In a review of interspe- (Clifford, 1970; Erwin and Engelen, gonium hybridizes freely in the wild cific crossability in Pelargonium, Horn 1992; Hanniford and Riseman, 1993) with the birch-leaf pelargonium (P. (1994) reported that species in the sec- usually credit the celandine-leafed pel- betulinum) (van der Walt and Ward- tion Pelargonium were crossed with argonium (P. fulgidum) with contrib- Hilhorst, 1977) and the large-flowered species in Polyactium, Hoarea, and uting the red color to regals, a sugges- pelargonium (P. saniculaefolium) (Jack- Glaucophyllum resulting in viable seeds. tion that probably originates with Sweet son, 1977). The latter resembles an- While the basic chromosome num- (Sweet, 1820-26). other large-flowered pelargonium (P. ber for the section Pelargonium is x = 11 Kato et al. (1991) investigated the grandiflorum), and they may be syn- (Albers and van der Walt, 1984), Knicely inheritance of petal blotches in regals onymous (van der Walt and Ward- and Walker (1966) found variable ploidy and demonstrated that five blotches are Hilhorst, 1977). Gibby and Westfold levels for species contributing to the dominant over two blotches on the (1986) reported that the large-flowered development of regals. Specifically, they upper petals, and that colorless lower pelargonium was used in hybridization reported 2N = 36 for the apricot gera- petals are dominant over colored ones. with the hooded-leaf pelargonium early nium, 2N = 22 for the celandine-leaved Mitchell et al. (1998) demonstrated in the 19th century. The large-flowered pelargonium, 2N = 72 for the rose that either flavonoids or carotenoids pelargonium was introduced to England geranium, and 2N = 54 for the rose- were responsible for cream and yellow in 1794, nearly a century after the scented pelargonium. His report differs pigmentation, and anthocyanins were hooded-leaf pelargonium (Harvey, somewhat from Albers and van der Walt responsible for all other colors. The 1860) had been introduced. The birch- (1984) for which the latter researchers major anthocyanins identified were the leaf pelargonium had been in cultiva- report 2N = 22 (apricot geranium), 88 (rose geranium), and 66 (rose-scented cultivars of the time, including dressing these problems: Oglevee, Ltd. geranium). Albers and van der Walt ‘Grossmama Fischer’ (translation: of Connellsville, Pa., and Pennsylvania (1984) also report 2N = 22 for birch- ‘Grandma Fischer’), ‘Fruhlingzauber’ State (Penn State) University pelargo- leaved pelargonium, heart-leaved pelar- (translation: ‘Spring Magic’), and nium breeding program at University gonium, and P. cucullatum subsp. ‘Ostergruss’ (translation: ‘Easter Greet- Park. strigifolium. Gibby and Westfold (1986) ing’). Sales of Faiss’ ‘Marie Vogel’ ex- Efforts to improve horticultural report 2N = 22 for the large-flowered ceeded other regal cultivars, in all coun- qualities of regals began at Penn State pelargonium. Given the above chromo- tries up to the early 1950s (Bode, under the direction of Richard Craig in some counts, Albers and van der Walt 1966b). From the cross between ‘Marie 1977. The first patented cultivars re- (1984) concluded that the basic chro- Vogel’ and ‘Beverly Fabretti’ William leased from this program belong to the mosome number in the section Pelargo- Schmidt developed the cultivar ‘Grand Elegance series: ‘Allure’, ‘Crystal’, ‘Fan- nium is x = 11, designating plants hav- Slam’, from which the sport ‘Lavender tasy’, ‘Flair’, ‘Majestic’, and ‘Splendor’. ing 2N = 22 as diploids, those having Grand Slam’ originated. The most important criteria in the de- 2N = 66, hexaploids, and those having Besides William Schmidt, numer- velopment of these cultivars were pre- 2N = 88, octoploids. ous other notable breeders in the United dictable flowering response and im- The interspecific hybridization be- States introduced improved cultivars proved postproduction quality. Tem- tween species in the development of from the 1930s through the 1950s, peratures for floral initiation were main- regals has contributed to the complex including Ernest Robert (Bode, 1966b); tained at a minimum of 58 oF (14 oC) to cytogenetics of regal cultivars. Regals R.M. Henley and Clara Sue Jarrett achieve the desired flowering response are believed to be polyploids of complex (Schmidt, 1955); Albert H. Cassidy and in the development of new genotypes. parentage (Craig, 1982). Reported chro- Richard Diener (Schmidt, 1956); New additions to the Elegance series mosome numbers for regal cultivars Howard Kerrigan (Schmidt, 1956; have been developed both at the Penn vary from 2N = 43 and 44 (Coffin and Sefton, 1993); Fred and Alice Bode, State and at Oglevee, Ltd.: ‘Tiara’, ‘Bril- Harney, 1978), 44 (Gauger, 1937), 45 Amanda Brown and her sons Lowell liance’, ‘Dandy’, ‘Symphony’, ‘Fascina- (Takagi, 1928), to 17, 18, and 35 and Waverly, and Harry and Clara May tion’, ‘Enchantment’, ‘Sandra’, ‘Erin’, (Darlington and Wylie, 1955), and 36, (Sefton, 1993). ‘Lois’, ‘Debutante’, and ‘Rapture’. 42, and 45 (Knicely and Walker, 1966). CURRENT HYBRIDIZATION EFFORTS. David Lemon, currently with Thus, aneuploidy is not uncommon Throughout the history of regals, the Oglevee, Ltd., first began working on among regal cultivars. breeding focus has been on flower form regals in 1986. Many of the cultivars he CULTIVAR DEVELOPMENT. Regals have and color, and, to some extent, plant developed are included in the Maiden been highly prized for their spectacular form: short petioles and short intern- series: ‘Maiden Lilac’, ‘Maiden Orange’, floral displays for many years. Flower odes are preferred. Many hobby breed- ‘Maiden Rose Pink’, and ‘Maiden Pet- form was often the primary focus in ers continue to breed beautiful plants ticoat’ are grown and marketed by developing new genotypes (Bode, with superior ornamental qualities. Oglevee, Ltd. and were released begin- 1966a). Some of the common names These plants are often traded or sold ning in 1996 (Oglevee, 1996). Two for regals are based on various informally through geranium societies additional cultivars in the Maiden series flower-types. For example, the large- in various locales. More information on were originally sold as Vavra cultivars: flowered show pelargonium flowers were the work of hobbyists is available through ‘Maiden Sunrise’ and ‘Maiden Red’. spotted, fringed and semidouble; geranium and pelargonium associations The Vavra cultivars were originally de- smaller-flowered types were referred to in the United States (International Ge- veloped by Wolfgang Kirmann in Aus- as fancy pelargoniums (Clifford, 1970). ranium Society, Pasadena, Calif.), En- tria and included the cultivars ‘Josy’, The pansy-flowered geranium was a gland (British Pelargonium and Gera- ‘Dolly’, ‘Mary’, ‘Peggy’, ‘Macy’, smaller flowering regal that usually had nium Society, Ilford, Essex; British and ‘Honey’, and ‘Shirley’. In general, Vavra two upper petals with dark pigmenta- European Geranium Society, Clayton- cultivars are difficult to root, require tion while the three lower petals were le-Woods, Chorley, Lancashire), Canada night temperatures around 60 oF (16 white. The color pattern coupled with (Canadian Geranium Society, oC) for floral initiation and are less heat- very rounded petals imparts on this Mississauga, Ontario) and Australia (In- tolerant than other modern cultivars flower a striking resemblance to the ternational Geranium Society, Wembley (Oglevee, 1995). For these reasons many pansy (van Pelt-Wilson, 1965). ‘Lady Downs, Western Australia). Vavra cultivars have been discontinued Washington’ or ‘Martha Washington’ Until recently, cultivars have not for sale in the United States, but are still was an early cultivar popular in the been developed specifically for modern available in Europe. United States (Hanniford and Holcomb, greenhouse production and often ex- Oglevee, Ltd. also markets the 1982). hibited several horticultural constraints. Royalty series that were originally devel- EARLY HYBRIDIZATION EFFORTS. Ger- One major production limitation is the oped by Ernest Walters, a hobbyist regal man hybridizers modified the existing cool temperature requirement for flower breeder in England. Walters’ primary small-flowered type regals into the large- induction and development. Other limi- goal was to develop regals with ex- flowered types which also had an ex- tations that must be overcome for suc- tended flowering periods. He accom- tended flowering period (van cessful greenhouse production include plished that, along with dwarf habit, Pelt-Wilson, 1965). Regal cultivars de- ease of rooting, predictable flowering natural free-branching habit, and inflo- veloped by Carl Faiss in Germany were response, whitefly resistance, shipping rescences held high above the foliage introduced to California in the 1920s ability, and postproduction quality. (Walters, 1985). While many of the (Schmidt, 1955). Many of these culti- Currently two hybridization programs original Royalty cultivars have been su- vars performed well and were leading exist in the United States that are ad- perseded in the United States by newer cultivars, the traits they exhibited have eters such as number of leaf nodes, rate they flowered. Short day-treated plants been integrated into newer cultivars. Of of leaf development, dry weight or leaf were provided an 8 h day of ambient light, the original Royalty series, only the area (Loehrlein, 1997). while long-day-treated plants received cultivar Baroness is still available through Regals are day-neutral plants with ambient lighting supplemented with Oglevee, Ltd. David Lemon has added respect to flowering. Research con- tungsten lighting (160 J·cm–2·d–1) to ‘Imperial’, ‘Excalibur’, ‘Emperor’, and ducted prior to 1980 indicated that provide an 18 h photoperiod. They ‘Monarch’ cultivars to the Royalty se- flowering was controlled by tempera- reported an interaction such that at the ries, and the former Vavra cultivar ‘Em- ture and irradiance (Crossley, 1968; higher (64 oF) average temperature flow- press’ is also now included in the Roy- Hackett and Kister, 1974; Nilsen, 1975; ering was advanced by 36 d without an alty series. ‘Camelot’ is a new addition Post, 1942; Powell and Bunt, 1978). unacceptable reduction in flower num- to the Royalty series that was developed However, the cultivars studied are no ber when irradiance was increased. They at Pennsylvania State University. longer economically viable or widely also found that at higher (64 oF) average Both Richard Craig at Penn State available. Nevertheless, even modern temperature and short (8 h) days, flow- and David Lemon at Oglevee, Ltd. regal cultivars vary in response to tem- ers completely aborted. Erwin and continue to develop new cultivars of perature and irradiance. Furthermore, Engelen (1992) also reported flower regals. Objectives for genetic improve- floral initiation and floral development bud abortion at average daily tempera- ment include resistance to petal abscis- may be thought of and treated as two tures greater than 61 oF. Therefore when sion, elimination of cool temperature separate processes, with differing re- day temperatures are high night tem- and high irradiance requirements for quirements for optimal response during peratures must be lowered to maintain flowering, and greenhouse whitefly each process. For example, Hackett and a low average daily temperature. (Trialeurodes vaporariorum) resistance. Kister (1974) reported an interaction Other goals include improved perfor- between temperature and irradiance on Cultural requirements mance under adverse environmental flowering, but did not differentiate the PROPAGATION. Regals are vegeta- conditions including heat and humidity floral initiation process from the floral tively propagated because of low seed tolerance, and improved petal tolerance development process. Both processes set. Several reasons include variable fer- to rain. may be affected by irradiance and tem- tility of ovules and pollen (Stuart et al., In Germany and England, two rela- perature, with interactions between the 1993, Stuart and Jourdan, 1994), envi- tively new commercial programs have two, and with variable genotypic re- ronmental effects on fertility (Stuart and been initiated. Elsner pac Jungpflanzen sponses. Hanniford, 1990), and complex inter- (Dresden, Germany) is focusing on de- Erwin (1991) found that when specific cytogenetics (Knicely, 1966). veloping regals with reduced cooling provided 8 h photoperiod under ambi- However, vegetative propagation pre- requirements (3 to 4 weeks below 50 oF ent light, ‘Fanatsy’ bloomed only when sents an additional set of problems, (10 oC)) for floral initiation, compact average daily temperatures remained at including the necessity of maintaining a growth habit that does not require or below 61 oF (16 oC). When ‘Fantasy’ large supply of stock plants, poor root- growth regulators, soft, crack-resistant was provided 8 h ambient light at 54, ing due to environmental and genetic foliage for better shipping performance, 64, or 75 °F (12, 18, or 24 oC) plus 3 h components, and a need for stringent and uniform flowering (Andrea of red lighting at 25 fc (5 mmol·s–1·m–2) control of environmental and sanitation Michalik, personal communication). during the first 3 h of night at 54 or 64 factors to prevent infection by patho- Elsner pac Jungpflanzen will market oF, plants bloomed 4 to 13 d earlier than gens. and distribute their new cultivars world- those plants which received only an 8 h Craig and Oglevee (1990) have wide; they will be available in the United photoperiod. developed protocols for successful com- States through Oglevee, Ltd. In a study on floral initiation in mercial production of regals. For initia- Floranova (Norfolk, England) is regals, nine cultivars were grown at four tion, they recommend growing investigating the possibility of develop- daily light integrals and constant tem- propagules at 57 to 63 oF (14 to 17.2 ing seed-raised regals having a reduced perature of 60 oF (Loehrlein and Craig, oC) with cumulative irradiance of 350 to vernalization period. In addition, nu- 1999). They found that floral initiation 425 mol·m–2 applied over a 28-d period merous nurseries in England specialize could be manipulated in some cultivars. (12 to 15 mol·m–2·d–1). Supplemental in regals and purchase hybrids devel- For example, ‘Splendor’, ‘Duchess’ and lighting is recommended to ensure a oped by independent breeders (F. ‘Jennifer’, initiated floral meristems 27 16-h photoperiod and the minimum Brawner, personal communication). to 47 d earlier as daily light integral cumulative irradiance. increased from 5 to 20 mol·d–1. While Growers typically purchase cuttings Environmental requirements other cultivars, including ‘Fantasy’ and from a professional cutting producer. FLOWERING PROCESS. At the time of ‘Princess’ initiated floral meristems in Rooted and nonrooted (callused) veg- visible flower buds, all the stages of about 30 d, regardless of daily light etative cuttings are available, as well as meristem ontogeny from vegetative to integral. rooted cuttings that are pre-budded. floral have been completed. In regals, Powell and Bunt (1978) examined Rooted prebudded cuttings are sold in floral ontogeny occurs in the meristem the effects of temperature and irradi- 3-inch (7.5-cm) pots and require up to in four stages: 1) vegetative, 2) transi- ance on floral development, following 7 60 d to finish a marketable plant. Rooted tional, 3) early inflorescence and floral weeks of cool pretreatment in an un- cuttings should flower in 12 to 14 weeks, organ development, and 4) floral organ heated greenhouse. Plants were then while nonrooted, callused cuttings will development (Loehrlein and Craig, grown for 3 weeks at 50, 55, or 61 oF (10, require an additional 2 to 3 weeks and 2000). Floral ontogenetic development 13, or 16 oC) and then half were left and must be provided the appropriate envi- is not correlated to plant growth param- the other half were moved to 61 oF until ronment for root development as speci- fied later in this section (Oglevee, 1995). MICROTECHNIQUES. Root establish- irrigation to 100 ppm N and K (Erwin Cuttings are made by removing ment problems may be circumvented and Engelen, 1992). 2.5 to 3.0 inch (6.4 to 7.5 cm) of a with somatic embryogenesis. Efforts to Regals are grown under cool tem- terminal shoot having four to six leaves. develop this alternate propagation peratures, so ammoniacal nitrogen The stem should be succulent and tur- method with regals have been advanced should be avoided. Phosphorus, cal- gid, and may be removed by hand or by by the research of Marsolais et al. (1991) cium, magnesium and micronutrients using a sterilized knife or pair of clippers. and Wilson (1994). Micropropagation should be pre-mixed with the soilless Lower leaves should be removed, leav- techniques have been researched by media (Craig and Oglevee, 1990), and ing two fully expanded leaves and the Cassells (1987a), Hauser (1993) Hauser controlled release fertilizers may be used terminal growing tip (Hanniford and et al. (1995) and Horn (1988). Propa- as an alternative to liquid fertilizer. For Holcomb, 1982). Flower buds should gation by callus-derived protoplasts was example, 14–6.2–11.6 controlled re- be removed. Two to three leaf nodes studied by Dunbar (1991); and in vitro lease fertilizer has been used successfully should be inserted into the rooting culture was investigated by Nord (1989). at a rate of 0.5 teaspoon (2.4 g) per 6- media. One or several of these techniques may inch (15-cm) pot at the time of trans- Care must be taken when inserting replace cutting propagation as the pre- planting and 4 weeks later (Hanniford the cutting, as wounding may create an ferred method of production in the and Holcomb, 1982). Magnesium and/ infection site for botrytis (Botrytis future. Reports on ovule culture of P. or iron deficiencies commonly occur cineria), to which regals are susceptible ×domesticum hybrids have been given due to high pH of the soilless media. (Hanniford and Holcomb, 1982). Dust- by Kato and Tokumasu (1983), and Media pH should be maintained at or ing the cutting with a rooting hormone results are further described by Kato et below 6.8 (Erwin and Engelen, 1992). compound containing a fungicide will al. (1988, 1989). Regals are sensitive to soluble salts, help reduce botrytis and stimulate root- GENETIC TRANSFORMATION. Boase et therefore soluble salt levels should be ing (Hanniford and Holcomb, 1982). al. (1996, 1998) reported on successful monitored regularly (Armitage and After potting, cuttings may be drenched Agrobacterium-mediated transforma- Kaczperski, 1992). Soluble salts in the with a fungicide as a preventative mea- tion of the regal cultivar ‘Dubonnet’. growing medium should not be allowed sure (Armitage and Kaczperski, 1992). The goal of their study was to transfer a to exceed 0.75 ds·m–1 (Craig and Commercially, cuttings are placed range of flavonoid and plant morphol- Oglevee, 1990). Soil and foliar testing into Rubber Dirt plugs (Oglevee, Ltd., ogy genes. Bradley et al. (1998) also should be conducted in developing an Connellsville, Pa.). Rubber Dirt is com- successfully transformed ‘Dubonnet’, accurate fertilization regime (Oglevee, posed of peat moss, water, and a hydro- but failed to obtain phenotypic alter- 1999). philic polymer. However, use of any ation in transformants expressing the CARBON DIOXIDE. Specific recom- well-drained media, with pH adjusted transgene Lc (leaf color) of maize. mendations for CO2 supplementation to 5.5 to 6.0 should be adequate for SEASON. Regals are sold in retail have not been developed. However, good root development (Oglevee, stores as flowering potted plants in the regals would most likely benefit from
1995). spring. They are most readily available supplemental CO2 because it encour- Cuttings are placed under a mist between Easter and Mother’s Day. ages vegetative growth (Armitage and environment for the first 3 d, with fre- Regals are produced in pots ranging in Kaczperski, 1992). quent misting beginning 1 h after sun- size from 4 to 8 inches (10 to 20 cm). IRRIGATION. Propagules should be rise to 1 h before sunset. In the morning Regals are sold through florist’s shops misted regularly during the root devel- apply mist at a frequency of 8 to 10 s or local garden centers. Regals do not opment period. Plants should be well- every 30 min, increasing to 8 to 10 s ship well, due to the tendency of petals watered when first planted. Subse- every 7 min during the heat of the day, to abscise. In favorable areas of cool quently, plants should be kept adequately then decrease to 8 to 10 s every 30 min night temperatures and low rainfall regals moist and not allowed to dry out, and towards the end of the day (Hanniford are excellent outdoor plants, particu- excessive watering should be avoided. and Holcomb, 1982). Misting may be larly in containers. Petal abscission is a (Armitage and Kaczperski, 1992). reduced to midday applications after the problem in areas of frequent rainfall or MEDIA. Regals can be produced in first week, and roots should have begun overhead watering. In coastal California a wide variety of media components. to develop (Hanniford and Holcomb, they may bloom in containers nearly Regardless, they grow best at a pH of 1982). By the middle of the second year-round. 5.5 to 6.0 in a well-drained, porous week, misting may be discontinued as NUTRITION. Regals should be placed soilless media (Armitage and Kaczperski, long as wilting does not occur. on a fertilizer program of 150 to 250 1992). Vermiculite should be avoided, Heating of the rooting medium at ppm (mg·L–1) nitrogen (N) and potas- due to its tendency to compact (Oglevee, 70 to 75 oF (21 to 24 oC) is necessary for sium (K) (Hanniford and Holcomb, 1999). Nonsterile media must be pas- the successful rooting of cuttings (Craig 1982; Artmitage and Kaczperski, 1992). teurized to avoid problems with botrytis and Oglevee, 1990). After 2 weeks, the Specific requirements may vary for indi- (Armitage and Kaczperski, 1992). medium temperature may be reduced vidual cultivars and may be adjusted HEIGHT CONTROL. Chlormequat re- to 62 to 65 oF (17 to 18oC) (Craig and depending on local environment and stricted stem growth on noncooled (un- Oglevee, 1990). In 4 to 6 weeks plants location. Nevertheless, it is critical that initiated) ‘Lavender Grand Slam’, but should be adequately rooted (Hanniford recommended nutrient levels are had no significant effect on cooled (ini- and Holcomb, 1982). Rooted cuttings achieved early in production. There- tiated) plants (Holcomb, 1979). Nei- are then placed into the floral initiation fore, the first watering should contain ther ancymidol nor daminozide affected environment recommended by Craig 300 to 400 ppm of N and K. Levels may stem elongation in either cooled or and Oglevee (1990). then be dropped during subsequent noncooled plants. Giberellic acid did not increase stem elongation of either Castañé and Albajes (1992) found vate both zonal geraniums and regals. cooled or noncooled plants. that the adult greenhouse whitefly has Bonzi (paclobutrazol) at 8 to 10 a preference for regal cultivars with Physiological disorders ppm is effective as height control (C. larger leaves and fewer trichomes. This Oedema is a nonparasitic disease Batschke, personal communication). suggests potential for genetic selec- related to insufficient water loss from Cycocel (46% chlormequat chloride) tion in developing whitefly-resistant the leaves. Oedema usually affects ivy- sprays of 500 to 1500 ppm (Craig, cultivars. Until that occurs, however, leaved geraniums, but can occur on 1986; Erwin and Engelen, 1992) or use of a systemic insecticide or other regals as well (Fletcher, 1984). Regals 3000 ppm (C. Batschke, personal com- control method is recommended to do not perform well outdoors in tem- munication) can be used during forcing ensure long-lasting pest control. perate continental climates. Flowering of nonpinched regal plants. However, 2 PATHOGENS. Regals are a carriers is inhibited by high night tempera- h of lighting in the middle of the dark for bacterial blight (Xanthomonas tures in summer. Rain contributes to period may be sufficient to produce the campestris pvr. pelargonii), which can petal abscission. However, in coastal desired height control. For optimal devastate geraniums. Bacterial blight areas where cool night temperatures height control, this light may be pro- causes a vascular wilt in zonals (Knaus prevail, regals grow and bloom freely vided by high intensity discharge (HID) and Tammen, 1967). (Post, 1949; Hanniford and Holcomb, lamps with increased irradiance in the Leaf spot (Alternaria alternatai) 1982). Smaller-flowered types perform blue spectrum. (R. Craig, personal com- (Fletcher, 1984), grey mold (Botrytis better outdoors and are not as suscep- munication). If HID lights are used, cinerea), black stem rot (Pythium tible to botrytis infection (D. Lemon, Cycocel is not needed (Craig, 1986). splendens) (Fletcher, 1984; Horst, personal communication). Application of zero or negative 1990), verticillium wilt (Verticillium Postharvest DIF (day – night temperatures = DIF), alboatrum and V. dahliae) (Fletcher, where night temperatures equal or ex- 1984), Rhizoctonia (Erwin and Petal abscission is a problem dur- ceed day temperatures, particularly in Engelen, 1992) and viruses also affect ing postharvest and is accentuated by the first 2 to 4 h of daylight is adequate regals (Craig, 1989). Crown gall (Agro- high temperature, low light, and eth- for height control of regals (Erwin and bacterium tumefaciens) and leafy gall ylene (Post, 1949; Deneke et al., 1990; Engelen, 1992). For best results regals (Corynebacterium fascians) occur on Armitage and Kaczperski, 1992). As a may be grown with equal day and night occasion (Fletcher, 1984). Geranium matter fact, regals are among the most temperatures, or with 5 to 7 oF (3 to 5 rust (Puccinia pelargonii) can be a responsive species to ethylene (Deneke oC) warmer day than night tempera- serious problem in geraniums. Rust et al., 1990). Forcing temperature also tures. Application of zero or negative resistant cultivars of regals do exist, contributes to flower petal abscission, DIF throughout the day will result in however (McCoy, 1975). such that lower temperatures during reduced green foliage coloration (Erwin The most effective, and some- forcing resulted in fewer petals abscis- and Engelen, 1992). times the only control for diseases on ing during and subsequent to shipping SPACING. Distance between pots regals is to use disease-free cuttings (Evensen and Olson, 1992). For ex- should equal the diameter of the pots. from culture and virus indexed sources ample, rooted cuttings forced for 4 Therefore, 6-inch (15-cm) pots should (Fletcher, 1984; Horst, 1990). Inci- weeks in a controlled environment be placed 1/ft2 (10.75/m2), while 4- dences of botrytis may be avoided by growth chamber at 64/55 oF (18/13 inch pots may be placed 2.5/ft2 (26.87/ proper plant spacing, reducing or elimi- oC) day/night versus 70/61 oF (21/ m2) (Craig and Oglevee, 1990). nating overhead watering, and by 16 oC) day/ night for 18-h photoperi- Pinching and disbudding. Plants speedy removal of all infected plants or ods prolonged by 5 d the floral display may be pinched when transplanted to plant parts (Horst, 1990). in a postproduction environment encourage side shoots and produce a Serological and bioassay tests can (Evensen and Olson, 1992). larger finished plant (Armitage and be conducted to detect the presence of Silver thiosulfate (STS) reduced Kaczperski, 1992). Plants should be pathogens (Cassells, 1987b), includ- ethylene sensitivity of regal florets and pinched after rooting and before floral ing in vitro screening of bacterial blight increased longevity of florets that initiation (Craig and Oglevee, 1990; (Dunbar and Stevens, 1989). A so- reached anthesis when applied to plants Armitage and Kaczperski, 1992). When phisticated method has been devel- in the bud stage (Deneke et al., 1990). pinching is used, the crop is delayed by oped to produce disease-indexed However, increased incidences of 2 to 3 weeks (Craig and Oglevee, 1990). propagules, combining culture index- Pythium have been shown to be re- ing, heat treatment of culture-indexed lated to STS on zonal geraniums Diseases and insects material, virus-indexing, and a combi- (Hausbeck et al., 1987), rendering it INSECT PESTS. Mealy bugs nation of bioassays and enzyme-linked of little use in regal production. Cur- (Planococcus citri, Pseudococcus sp.), immunosorbent assay (ELISA) tests rently STS is not registered for regals. aphids (Myzus persicae, Aphis gossypii), (Craig and Oglevee, 1990; Oglevee, Since regal flower buds are not mites (Tetranychus urticae), thrips 1995). The availability of clean stock sensitive to ethylene, shipping-related (Frankliniana occidentalis), and green- has eliminated virus diseases as a major petal abscission could be reduced if house whiteflies are common pests of problem of regals (Fletcher, 1984). regal plants were shipped during the regals (Hanniford and Holcomb, 1982; The use of culture- and virus-indexing bud stage. 1-Methylcyclopropene Craig, 1989). Among these, the green- for pathogens is the most reliable (MCP) may prove to be a viable alter- house whitefly is the major pest affect- method developed to ensure clean native as an ethylene block (Serek et ing regals (Hanniford and Holcomb, stock of all propagules. This is espe- al., 1995). However, sufficient research 1982; Adams, 1987). cially important for growers who culti- has not been conducted on regals to determine the benefits and possible 1998. An improved method for transfor- Deneke, C.F., K.B. Evensen, and R. Craig. disadvantages. mation of regal pelargonium (Pelargonium 1990. Regulation of petal abscission in Plants do not perform well under ×domesticum ‘Dubonnet’) by Agrobacte- Pelargonium ×domesticum. HortScience low-light conditions such as those rium tumefaciens. Plant Sci. 139(1):59– 25(8):937–940. 69. found inside buildings. Plants should Dunbar, K.B. 1991. Plant regeneration be placed in an area receiving adequate Bode, F.A. 1966a. Character study of a from callus-derived protoplasts of Pelargo- light of at least 6 to 12 fc (30 to 60 queen. Geraniums around the world nium ×domesticum. Plant Cell Rpt. µmol·s–1·m–2) (Olson and Evensen, 8(4):76–81, 95. 10(8):417–420. 1990), moderate temperatures, and Bode, F.A. 1966b. Character study of a Dunbar K.B. and C.T. Stevens. 1989. An good ventilation to help reduce ethyl- queen. Part II. Geraniums around the world in vitro screen for detecting resistance in ene buildup (Craig and Oglevee, 9(2):28–35. Pelargonium somaclones to bacterial blight 1990). of geranium. Plant Dis. 73:910–12. Bradley, J.M., S.C. Deroles, M.R. Boase, Harvest stage S. Bloor, E. Swinny, and K.M. Davies. Erwin, J. 1991.Cool temperatures are still 1998. Variation in the ability of the maize critical on regals. Minn. Comm. Flower Potted plants are marketable when Lc regulatory gene to upregulate flavonoid Growers Assn. Bul. 40(3):3–4. petal color is visible but flower buds biosynthesis in heterologous systems. Plant are not yet ready to open. Since most Sci. 140:31–39. Erwin, J. and G. Engelen. 1992. Regal regal flowering plants are produced geranium production. Minn. Comm. Cassells, A.C. 1987a. Adventitious regen- Flower Growers Assn. Bul. 41(6):1–9. and sold close to the retail outlets, × timing of shipments can be accurately eration in Pelargonium domesticum Bailey. Acta Hort. 212:419–425. Evensen, K.B. and K.M. Olson. 1992. controlled. Some garden centers and Forcing temperature affects postproduction nurseries sell at the production loca- Cassells, A.C. 1987b. Problems posed by quality, dark respiration rate, and ethylene tion. cultivable bacterial endophytes in the es- responsiveness of Pelargonium Although regals perform well tablishment of axenic cultures of Pelargo- ×domesticum. J. Amer. Soc. Hort . Sci. × outdoors in some geographical regions, nium domesticum: the use of Xanthomonas 117(4):596–599. their commercial potential may long pelargonii specific ELISA, DNA probes, and culture indexing in the screening of Fletcher, J.T. 1984. Disease of greenhouse remain in the potted plant sales arena. antibiotic treated and untreated donor plants. Longman group Ltd., New York. It remains to be seen whether the plants. Acta Hort. 225:153–161. Gauger, W. 1937. Ergebnisse einer genetics are present, or can be intro- Castañé, C. and R. Albajes 1992. Pelargo- zytologischen untersuchung der familie duced from yet other species, for the Geraniaceae. I. Planta 26:529–531. desired outdoor performance in hu- nium cultivar selection by adults of green- mid regions of moderate to high rain- house whitefly (Homoptera: Aleyrodidae). Gibby, M. and J. Westfold. 1986. A cyto- Environ. Entomol. 21(2):269–275. fall, or in regions where warm nights in logical study of Pelargonium sect. summer are common. Until such im- Clifford, D. 1970. Pelargoniums, includ- Eumorpha (Geraniaceae). Plant Sys. Evol. 153:205–222. provements are made, though, regals ing the popular ‘Geranium’. Blandford may continue to have a special niche in Press, Chatham, England. Hackett, W.P. and J. Kister. 1974. 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