Yield and Fruit Quality Traits of Atemoya also limits fruit set. Nitidulid beetles (Carpophilus sp. and Urophorus sp.) Hybrids Grown in Puerto Rico are the single most important polli- nators of atemoya flowers and other annonaceous crops (Nadel and Pena,~ Ricardo Goenaga1 and David Jenkins 1994). Fruit shape varies from conical to ovate; it has slight to pronounced surface protuberances, green-to greenish- ADDITIONAL INDEX WORDS. tropical horticulture, tropical fruits, soluble solids concentration, Annona squamosa · A. cherimola yellow skin and contains 10 to 40 dark brown to black seeds. Fruit pulp SUMMARY. As consumers seek healthy and more diverse food products, the demand is white, smooth textured, sweet with for tropical fruits has increased significantly during the last 15 years. There is a lack a custard-like consistency (Campbell of formal experimentation to determine the yield performance and fruit quality Annona squamosa · A. cherimola and Phillips, 1980; Crane et al., traits of atemoya ( ) hybrids. Six atemoya hybrids 2013). The fruit is high in dietary (‘Bradley’, ‘Geffner’, ‘Priestly’, ‘Lisa’, ‘47-18’, and ‘75-9’) grown on an Oxisol soil were evaluated for 4 years at Isabela, PR. ‘Geffner’ and ‘Lisa’ had the highest fiber and vitamin C and can range in number of marketable fruit averaging 8542 fruit/ha, and the highest yield of weight from 200 to 900 g (Meadows marketable fruit, averaging 1507 kgÁhaL1; they did not differ from each other, but and Oswald, 2012). were greater than all other hybrids. Individual weight of marketable fruit was There is very little information significantly higher in ‘75-9’ and ‘Priestly’ which averaged 264.8 g. Significantly available on total production area of higher soluble solids concentration values were obtained from fruit of ‘75-9’, atemoya worldwide. The largest pro- ‘Bradley’, and ‘Geffner’ which averaged 23.8%; they did not differ from each other, ducer in the United States is Florida, but were greater than all other hybrids. with annual production estimated at 50,000 lb and an average seasonal s consumers seek healthy and The atemoya grows well in trop- price of $4.00/lb (Mossler and more diverse food products, ical and subtropical climates from sea Crane, 2012). In the United States, A the demand for tropical fruit level to an elevation of 1000 m. It small orchards are known to have has increased significantly during the adapts to a wide range of soil types been established in Hawaii, CA, and last 15 years with an estimated value including sandy or heavy soils; how- Puerto Rico. of production at $18 billion in 2009 ever, it does not withstand water- Commonly used hybrid cultivars (Food and Agriculture Organization logged soils particularly when it is for commercial production include of the United Nations, 2011). Be- grafted onto sugar apple (Crane Geffner, Page, African Pride, and longing to the Annonaceae family, et al., 2013; Morton, 1987). In Flor- Bradley (Crane et al., 2013). Produc- the atemoya is an interspecific hy- ida orchards, atemoya budwood is tion of fully matured trees of these brid between the sugar apple (Annona usually grafted onto custard apple or hybrids is estimated to range from 75 squamosa) and the cherimoya (Annona sugar apple rootstocks; however, the to 200 fruit/year (Crane et al., 2013). cherimola) (Nakasone and Paull, 1998). most commonly used rootstock in However, results from long-term rep- The sugar apple is indigenous to the Israel is the cherimoya (Campbell licated field trials to evaluate these and highlands of Peru and Ecuador, and and Phillips, 1994; Morton, 1987). other hybrids are very limited (Crane the cherimoya is widely distributed Poor fruit set is the key obstacle et al., 2013). The objective of this throughout tropical South America for the cultivation of atemoya. The study is to evaluate the yield perfor- (Marleretal.,1994).However,the atemoya flowers exhibit protogynous mance and fruit quality traits of six term atemoya has also been used dichogamy (female function precedes atemoya hybrids grown in an Oxisol loosely in the literature for Annona male function). This incompatibility typical of the humid tropics. hybrids resulting from 1) crosses be- problem results in incomplete polli- tween custard apple (atemoya · A. nation and the production of mal- Materials and methods reticulata), 2) cherimoya · A. reticu- formed fruit (Mossler and Crane, This study was conducted in lata, and 3) for hybrids in which either 2012). For this reason, hand pollina- Puerto Rico at the U.S. Department A. squamosa or A. cherimola is used tion is often necessary to achieve of Agriculture, Agricultural Research interchangeably as male or female par- profitable yields. Lack of pollinators Service Research Farm in Isabela ents. In this paper, we use the term ‘‘atemoya’’ as the collective term for all Units these Annona hybrids. To convert U.S. to SI, To convert SI to U.S., multiply by U.S. unit SI unit multiply by USDA-ARS, Tropical Agriculture Research Station, 2200 P.A. Campos Avenue, Suite 201, Mayaguez, 0.4047 acre(s) ha 2.4711 Puerto Rico 00680-5470 0.3048 ft m 3.2808 We thank Angel Marrero, Pablo Rios, and Tomas 3.7854 gal L 0.2642 Miranda for their excellent field assistance. 2.54 inch(es) cm 0.3937 Mention of trade names or commercial products in 25.4 inch(es) mm 0.0394 this publication is solely for the purpose of providing 0.4536 lb kg 2.2046 specific information and does not imply recommen- 1.1209 lb/acre kgÁha–1 0.8922 dation or endorsement of the U.S. Department of 28.3495 oz g 0.0353 Agriculture. 1 ppm mgÁkg–1 1 1Corresponding author. E-mail: ricardo.goenaga@ars. 6.8948 psi kPa 0.1450 usda.gov. (°F – 32) O 1.8 °F °C(°C · 1.8) + 32 • August 2016 26(4) 547 VARIETY TRIALS (Coto clay: clayey, kaolinitic isohyper- 2007). Soil ammonium and nitrate shown commercial potential in non- thermic Typic Hapludox). The soil has were determined by steam distillation replicated plots at the nursery. Before a pH of 5.68, 154 mgÁkg–1 ammonium- (Mulvaney, 2007). Originally, the transplanting, the soil was chisel –1 nitrogen (NH4-N), 6.2 mgÁkg experiment was also established at plowed to a depth of 90 cm. Planting –1 nitrate-nitrogen (NO3-N), 5.8 mgÁkg a second location in a clayey, mixed, holes of 1.5-ft depth were dug with an phosphorous (P), 63.5 mgÁkg–1 potas- isohyperthermic Aquic Haplohumults auger connected by a drive shaft to sium (K), 1192 mgÁkg–1 calcium Ultisol soil. However, a combination the power-take-off unit of a tractor. (Ca), 93 mgÁkg–1 magnesium (Mg), of this site having a very heavy, clayey On transplanting day, each grafted 39 mgÁkg–1 iron (Fe), 245 mgÁkg–1 soil and a prolonged wet period due tree received 11 g granular P provided manganese (Mn), 2.80 mgÁkg–1 zinc to heavy rainfall caused high mortal- in the form of triple superphosphate. (Zn), and 1.42% organic carbon. The ity among plants forcing us to end Within a replication, plots for each 95-year (1919–2014) mean annual research at this site. hybrid contained two trees spaced rainfall is 1649 mm and Class A Six-month-old trees of hybrids 4 m apart and 6 m between adjacent pan evaporation is 1672 mm. Mean ‘Bradley’, ‘Geffner’, ‘Priestly’, ‘Lisa’, rows in a triangular array, 168 trees/ monthly maximum and minimum ‘47-18’, and ‘75-9’ grafted onto acre. As an effort to identify hybrids temperatures are 29.8 and 19.9 °C. ‘Lessard Thai’ sugar apple rootstock not needing artificial pollination, Soil samples were taken 2 months were transplanted to the field on 8 hand pollination was not performed before planting by taking 15 borings Aug. 2001 and were arranged in a in this study. This experiment was at a depth of 0–10 inches from each randomized complete block design surrounded by two guard rows of of the projected hybrid rows. Samples with four replications. ‘Bradley’ is custard apple seedlings. were air-dried and passed through one of the first named selections of Irrigation based on tensiometer a 20-mesh screen. Soil pH in water atemoya. ‘Geffner’ and ‘Priestly’ are readings was provided through drip and 0.01 M calcium chloride (1 soil : Israeli selections (Morton, 1987). irrigation with two 2-gal/h emitters 2 water) were measured with a glass ‘Lisa’ is ‘Libby’ cherimoya · ‘Red per tree spaced 1.8 m apart when the electrode. Exchangeable cations (po- Sugar’ sugar apple, ‘47-18’ and ‘75- soil water tension at a depth of 12 tassium, magnesium, and calcium) 9’ originated from controlled pollina- inches exceeded 50 kPa. Fertilization were extracted with neutral 1 N ammo- tion crosses of ‘Geffner’ atemoya · was provided every 3 months using nium acetate and determined by atomic ‘San Pablo’ A. reticulata, and ‘Spain’ a 15N–2.2P–16.3K–1.8Mg fertilizer absorption spectroscopy (Sumner and cherimoya · ‘Felipe Canul’ A. retic- at a rate of 185 lb/acre. Herbicide Miller, 2007). Phosphorus was ulata, respectively. All plant material (glyphosate) for weed control was extracted with 1 N ammonium fluo- was obtained from Zill’s High Per- applied only in strips within the plant- ride and 0.5 N hydrochloric acid and formance Plants (Boynton Beach, ing row. Weeds between rows were determined using the ascorbic acid FL) and shipped air freight to Puerto controlled with a tractor mower. method (Benton, 2001). Organic car- Rico. ‘Lisa’, ‘47-18’, and ‘75-9’ are Harvests were initiated in Jan. bon was determined by the Walkley– atemoya hybrids developed in that 2006. At this time, experimental trees Blackmethod(NelsonandSommers, nursery by Mr.