RESEARCH REPORTS Photoperiods of 8 and 12 hours Mai Dwarf’, Kaempferia ‘Grande’, Si- Growth and induced dormancy and t-root produc- phonichilus decora, and S. kirkii. tion of most of these gingers. Development Materials and methods Tissue culture plants of C. Responses of ingers are a member of the petiolata ‘Emperor’, C. thorelii and Ornamental Gingers Zingiberaceae family with Kaempferia ‘Grande’ S. decora, S. Gattractive fl owers that make kirkii were planted one per 15.2-cm- to Photoperiod them useful as potted plants. These diameter (6-inch) container in the tropical and subtropical perennials are greenhouse on 16 Aug. 1999. Tis- native to areas with small changes in sue culture plants of C. cordata were Mauricio J. Sarmiento and daylength and temperature throughout planted two per 15.2-cm-diameter the year (Zhang et al., 1995). Popu- container on 9 Sept. 1999. Rhizomes Jeff S. Kuehny larity of gingers as ornamental plants of Curcuma alismatifolia ‘Siam Tulip has continued to increase, and they are White’ (lacking t-roots) were planted ADDITIONAL INDEX WORDS. Curcuma now commonly grown in containers one per 12.7-cm (5-inch) container on alismatifolia, C. cordata, C. petiolata, under protected conditions in temper- 27 Aug. 1999. The substrate consisted C. thorelii, Kaempferia, Siphonichilus ate and subtropical regions that pres- of 50% peatmoss, 30% pine bark, and decora, S. kirkii, dormancy, photope- ent signifi cant variation in daylength 20% perlite (v/v), amended with 5.1 riod, rhizomes, t-roots throughout the year (Lekawatana and kg·m–3 (0.32 lb/yard3) dolomite lime- Pituck, 1998). To control growth and stone and triple superphosphate 2.7 SUMMARY Curcuma . Rhizomes of –3 3 alismatifolia ‘Chiang Mai Pink’ and fl owering of ginger, it is necessary to kg·m (0.17 lb/yard ) 0N–18P–0K. tissue cultured plants of C. cordata, understand the effects of photope- Plants were watered immediately after C. petiolata ‘Emperor’, C. thorelii, riod on vegetative and reproductive planting and drenched with a tank mix Kaempferia sp. ‘Grande’, Siphonichi- growth. of metalaxyl (Subdue 2E; Novartis, lus decora and S. kirkii were grown In general, gingers become dor- Greensboro, N.C.) and PCNB quin- in a greenhouse under 8-, 12-, 16-, mant in winter in response to short tozene (Terraclor 75% WP; Uniroyal and 20-hour photoperiods. All plants days (≤12 h) and low temperatures. Chemical, Middlebury, Conn.). Con- grown under the 8-hour photoperiod Curcuma alismatifolia, a ginger na- tainers were spaced 20.3 × 20.3-cm became dormant over a 15 week time tive to Thailand, fl owers during the (8 inches) centers and fertigated with period. After 90 days, most ginger species grown under the 16- and 20- summer and the fall in Israel, and in 24N–3.5P–13.3K (Peters 24–8–16 hour photoperiods were taller than winter growth is reduced (Hagiladi Tropical Foliage; Scotts Co., Marys- –1 those grown under 8 and 12 hours. A et al., 1997a). Studies have dem- ville, Ohio) at 150 mg·L (ppm) N. larger number of unfolded leaves was onstrated that short days and low Photoperiod treatments were indicated for all ginger species grown temperatures (not specifi ed) promote initiated 17 d after transplanting for under 16- and 20-hour photoperiods shoot dormancy in C. alismatifolia S. decora, S. kirkii, C. thorelii, C. peti- compared to those grown under 8- (Zhang et al., 1995). Other species olata and Kaempferia ‘Grande’, 18 d and 12-hour photoperiods except for of Curcuma tend to respond to short after transplanting for C. cordata and C. thorelli. The percentage of unfold- days (not specifi ed) by becoming dor- 6 d after planting for C. alismatifolia. ed leaves as determined by quartile mant (Lekawatana and Pituck, 1998). There were 12 experimental units indicated similar results. The number of underground rhizomes of C. alis- Globba winitii, another member of the (plants) per treatment for S. decora, matifolia, C. cordata, and C. petiolata Zingiberaceae, senesces in winter as a 16 per treatment of C. cordata and 3 increased when plants were grown at short-day response (Kuack, 1998). per treatment for S. kirkii, C. thorelii, 16 and 20-hour photoperiods. The Curcuma alismatifolia, along C. petiolata and Kaempferia ‘Grande’. number of tuberous-roots (t-roots) with most Curcuma species, has Plants in each photoperiod treatment increased as photoperiod decreased two underground storage organs: were arranged in a complete random- below 16 hours for C. alismatifolia, a rhizome and a spherical tuberous ized design. Plants received 8 h of C. cordata, C. petiolata, Kaempferia root designated as a t-root, attached natural light from 0900 to 1700 HR; sp. and S. kirkii. Siphonichilus decora to the rhizome by a connecting root 0, 4, 8, and 12 h of supplemental light produced no t-roots while C. thorelii (Hagiladi et al., 1997b). Tuberous were provided for the 8-, 12-, 16-, and produced the most t-roots at 16 hours. Vegetative growth of gingers roots (t-roots) have been indicated to 20-h photoperiod, respectively. Light grown in this study, except for C. have an important role in growth and source was 100-W incandescent light –2 –1 thorelii, was maintained and increased fl owering of the plant. Two or more bulbs at an irradiance of 11 µmol·m ·s at photoperiods of 16 and 20 hours. t-roots per propagule reduced time to (50.0 fc) at plant height. Temperature bloom by 18 d, and produced more set points in the greenhouse from plant- 137 Julian C. Miller Hall, Department of Horticulture, Louisiana State University Agricultural Center, Baton infl orescences per plant with longer ing date to 18 Oct. 1999 were 29 °C Rouge, LA 70803-2120. scapes (Hagiladi et al., 1997b). day/24 °C night (84.2 °F day/75.2 Use of trade names dose not imply endorsement of The objectives of this experi- °F night). From 19 Oct. to the end of the products named or criticism of similar ones not ment were to determine the effect the experiment, temperature set points named. Louisiana State University manuscript number 02-28-0042. We would like to thank The Fred C. of photoperiod on plant growth and were 27 °C day/21 °C night (80.6 °F Gloeckner Foundation and the American Floral En- development of Curcuma alismatifolia day/69.8 °F night). dowment for supporting this research. We would also ‘Siam Tulip White’ , C. cordata, C. Each week, the number of newly like to acknowledge Scotts Co. and Set Con Thailand for providing material for this research. petiolata ‘Emperor’, C. thorelii ‘Chiang unfolded leaves was counted as a 78 • January–March 2004 14(1) RR1 78 11/5/03, 10:43:16 AM Table 1. Effect of photoperiod on plant height for Curcuma alismatifolia ‘Siam Tulip White’, C. cordata, C. petiolata, C. thorelii, Kaempferia ‘Grande’, Siphonichilus decora, and S. kirkii after 61 and 90 d of photoperiod treatment. Ht (cmx) Photoperiod (h) Plant species Day 8 12 16 20 Curcuma alismatifolia 61 20.5 az 30.0 b 31.6 b 31.5 b 90 20.7 a 30.0 b 38.8 c 35.6 bc Curcuma cordata 61 42.5 a 44.0 a 45.3 a 46.8 a 90 Dy 42.7 a 50.2 b 49.0 b Curcuma petiolata 61 35.3 a 42.3 ab 56.3 bc 69.8 c 90 35.6 a 41.6 a 65.3 b 70.3 b Curcuma thorelii 61 31.3 a 33.0 ab 35.3 ab 37.3 b 90 D 32.0 a 37.3 b 38.0 b Kaempferia ‘Grande’ 61 25.3 a 30.3 ab 38.0 b 39.3 b 90 D 31.6 a 46.6 a 46.6 a Siphonichilus decora 61 27.4 a 29.8 a 37.0 b 41.8 c 90 27.7 a 29.9 a 48.0 b 53.8 c Siphonichilus kirkii 61 29.0 a 29.8 a 34.0 a 36.3 a 90 30.3 a 29.3 a 39.6 ab 47.8 b zMean separation of photoperiods by Tukey’s studentized range test, P = 0.05. Means within rows with different letters are signifi cantly different. yD = dormant. Plants were dormant before measurement. x1.0 cm = 0.39 inches. measurement of plant growth. On 2 photoperiod became dormant before C. thorelli and S. decora grown at 20 h Nov. and 1 Dec. 1999, plant height the end of the 17 weeks of treatment. was taller than those plants grown at 8 was measured vertically from the top None of the plants however, became h (Table 1). At 90 d all ginger grown of the pot to the tip of the longest leaf. dormant under the 18 and 20-h pho- at 20 h were taller than those grown The photoperiod treatments ended on toperiod. at 8 h, while Kaempferia ‘Grande’, C. 1 Feb. 2000 or after ≈17 to 20 weeks Photoperiod affected height of all cordata and C. thorelli had gone dor- of treatment. Plants that did not go ginger species evaluated. Plants grown mant and produced no more leaves. dormant during the course of the ex- under 20- and 16-h photoperiods were Similar results were found for orchid periment were forced into dormancy by taller than those grown under 12- or pansy (Achimenes spp.) a rhizomatous terminating irrigation. After all plants 8-h photoperiods. After 61 d, plant plant native from Mexico to Brazil, were dormant, weight of underground height of C. alismatifolia, C. petiolata, where a 16-h photoperiod produced organs (rhizomes and t-roots together) was measured and number of rhizomes and t-roots per plant was counted.