HORTSCIENCE 27(11):1227. 1992. Flowering of Eucrosia Influenced by Size and Watering Frequency Mark S. Roh U.S. Department of Agriculture, Agricultural Research Service, Florist and Nursery Crops Laboratory, Beltsville, MD 20705 Alan W. Meerow University of Florida, Institute of Food and Agricultural Sciences, Fig. 1. of Eucrosia bicolor. Research and Education Center, Ft. Lauderdale, FL 33314 flowered, three that weighed 23 g (11.7 Additional index words. South American bulb, , dormancy, Eucrosia cm in circumference) did not flower (E). Small bicolor bulbs that did not produce an inflorescence took > 60 days for leaf emergence. The min- Eucrosia Ker Gawler (Amaryllidaceae) is on 31 Mar. 1988. were grown in a imum size of bulbs capable of flowering native to Ecuador and Peru and consists of greenhouse maintained at a night minimum ranged from 21 g (10.7 cm in circumference) seven species (Meerow, 1987). They pro- (NT) of 16C until harvest on 17 Oct. 1988. to 27 g (12.5 cm in circumference). duce bulbs and are endemic primarily to sea- Day temperatures (DT) ranged from 26 to Microscopical dissection of E. bicolor did sonally dry regions of the lower, western 35C. not reveal flower buds at harvest, which sug- Andean slopes and Pacific coastal lowlands. All plants were watered on 15 and 30 Aug. gests that controlled watering did not induce In nature, the scape emerges before the leaves, 1988; subsequently, the plants were watered or influence flower bud initiation in this ex- which are elliptic and petiolate. The red as follows: 1) none (A); 2) 15 Sept. (B); 3) periment. Interruption of watering may not flowers are zygomorphic with long, delicate, 15 Sept. and 1 Oct. (C); and 4) 15 Sept. and have been long enough to induce flowering yellow that are fused into a staminal 1 and 15 Oct. (D and E). There were three or the bulbs may have been too small at har- cup (Fig. 1). pots per treatment. vest when watering was terminated on or be- Eucrosia bicolor var. bicolor has potential After bulb harvest, al! roots and leaves fore 15 Sept. (A and B). Flowering of as a cut flower. Neither the environmental were removed and bulbs were stored dry at Hippeastrum from mature bulbs resulted from requirements for flowering nor the minimum 20C for 30 days (A-D) or 60 days (E). Bulbs rapid extension of the scape by irrigation in- bulb size or circumference that can be forced were replanted, one bulb per 1.6-liter pot, terruption (Boyle and Stimart, 1987). has been determined. Based on research with on 17 Nov. 1988. Plants were grown in a The lack of acceleration of flowering in Hippeastrum hybridum Hort. (Boyle and greenhouse maintained at 21/16C (DT/NT) bulbs stored for 60 days at 20C (E) suggests Stimart, 1987), an experiment was con- until flowering. that 20C may not be an optimal temperature ducted to test the effect of controlled irri- A completely randomized design was em- for flower bud initiation from small bulbs. gation on flowering and to determine the ployed using a minimum of 17 bulbs per The effect of the watering treatment may have minimum bulb size for flowering. treatment, each weighing >16 g (>8.1 cm been masked by the effect of root and leaf Six bulbs of E. bicolor (< 3 cm in circum- in circumference). Dates of leaf and inflores- removal after bulb harvest plus dry storage ference) were planted in 2.6-liter pots con- cence emergence were recorded and, at at 20C. taining a sterilized growing medium composed flowering, the number of flower buds and Since controlled watering and storing bulbs of 3 soil : 4 perlite : 4 peatmoss (by volume, scape length from the nose of bulb to the at 20C failed to ensure early flowering in E. pH = 6.4). Plants were grown in a green- base of the were recorded. Days to bicolor, it may be necessary to investigate house maintained at a night minimum of 21C flowering were counted from 15 Aug. 1988. the effect of temperature during vegetative and fertilized weekly with 200 ppm N from Means were compared by Duncan’s multiple growth before harvest in conjunction with a 20N-8.6P-11.4K fertilizer (Peters 20-20- range test. controlled watering before bulb harvest. An- 20; Grace-Sierra, Allentown, Pa.) in 1986- Due to a great variation in flowering time, atomical work is needed to ascertain the 88. Plants were transplanted into 3.8-liter pots especially when the controlled watering presence of dormancy in relation to devel- treatments were started early (A and B), opmental stages of flower bud initiation. watering treatments had no significant effect on days to flower (Table 1), flower count Literature Cited Received for publication 8 Aug. 1991. Accepted (6.7-7.9), and scape length (36-42 cm). for publication 14 June 1992. We thank Thomas Boyle, T.H. and D.P. Stimart. 1987. Influence of H. Boyle for reading the manuscript. The cost of Inflorescence emergence spanned 36 days and irrigation interruptions on flowering of Hip- publishing this paper was defrayed in part by the flowering 17 days. Time required from peastrum ×hybridum ‘Red Lion’. HortScicnce payment of page charges. Under postal regula- inflorescence emergence to flowering spanned 22(6):1290-1292. tions, this paper therefore must be hereby marked 19 days (Table 1). Although one bulb that Meerow, A.W. 1987. A monograph of Eucrosia advertisement solely to indicate this fact. weighed 18 g (9.6 cm in circumference) (Amaryllidaceae). Syst. Bot. 12:460-492.

Table 1. Effect of watering and bulb size on flowering of Eucrosia bicolor.

zA: Watered only 15 and 30 Aug.; others on those dates as indicated. yNumber of bulbs flowered/sample size. xMean separation within columns by Duncan’s multiple range test at P = 0.05.

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