5. Bell, W. D. 1973. The role of triploids in Amaryllis hybridization. 23. Goedert, R. D. 1961. Hadeco amaryllis hybrids grown in South Af Plant Life 29:59-61. rica. Plant Life 17:85-86. 6. Bell, W. D. 1974. Stomatal size as an indication of Amaryllis polyp- 24. Goedert, R. D. 1982. The continuing pursuit of yellow. Plant Life loidy. Plant Life 30:89-90. 38:61-63. 7. Bell, W. D. 1977a. More potentials in Amaryllis breeding. Plant Life 25. Hayward, W. 1934. The Mead strain of the Nehrling amaryllis. Year 33:65-69. book of the Amer. Amaryllis Soc. 1:62-63. 8. Bell, W. D. 1977b. Double flowered Amaryllis. Proc. Fla. State Hort. 26. Kaicker, U. S. and H. P. Singh. 1979. Role of mutation breeding in Soc. 90:121-122. amaryllis. Plant Life 35:66-73. 9. Blossfeld, H. 1973. Breeding for yellow amaryllis hybrids. Plant Life 27. Ludwig 8c Co. 1948. The Ludwig hybrid Amaryllis. Herbertia 15:69. 29:56-58. 28. Meerow, A. W. 1987. Chromosome cytology of Eucharis, Caliphruria 10. Bose, T. K. and B. K. Jana. 1977 Regeneration of plantlets in Hippeas- and Urceolina (Amaryllidaceae). Amer. J. Bot. 74:1560-1576. trum hybridum in vitro. Indian J. Hort. 34:446-447. 29. Naranjo, C. A. and A. B. Andrada. 1975. El cariotipo fundamental 11. Buck, Q. Q. 1961. First flowering of newly imported Boshoff-Mostert en el genero Hippeastrum Herb. (Amaryllidaceae). Darwinia 19:566- hybrid amaryllis. Plant Life 17:84-85. 582. 12. Buck, Q. Q. 1978. Amaryllis breeding potentials - 1977. Plant Life 30. Phunsiri, S., P. Gavinlertvatana and P. Akavipat. 1982. Propagation 34:95-98. of Amaryllis through tissue culture. Kasetsart J. Nat. Sci. 16:44-51. 13. Cage, J. M. 1978. The role of Amaryllis species in future commercial 31. Ravenna, P. F. 1970. Amaryllis papilio. Plant Life 26:83. hybrids. Plant Life 34:98-100. 32. Seabrook, J. E. A. and B. G. Cumming. 1977. The in vitro propaga 14. Cage, J. M. 1978. 1980. End of a breeding project. Plant Life 36:79- tion of amaryllis {Hippeastrum spp. hybrids). In Vitro, J. Tissue Cult. 81. Ass. 13:831-836. 15. Cardenas, M. 1960. Amaryllis fragrantissima. Plant Life 16:32. 33. Shields, J. E. 1979. The ancestors of the amaryllis. Amaryllis Bui. 16. Cardenas, M. 1972. Amaryllis lapacensis. Plant Life 28:54. 1:2-6. 17. Cothran, C. D. 1979. Yellow-flowered and other Amaryllis hybrids. 34. Traub, H. P. 1934a. A preliminary amaryllis (Hippestrum) checklist. Plant Life 35:61-65. Yearbook of the Amer. Amaryllis Soc. 1:45-51. 18. Cothran, C. D. 1981. Continuing quest for large yellow flowering 35. Traub, H. P. 1934b. The Nehrling hybrid amaryllis. Yearbook of the amaryllis. Plant Life 37:110-111. Amer. Amaryllis Soc. 1:61. 19. Cothran, C. D. 1984. Large yellow amaryllis hybrids. Plant Life 36. Traub, H. P. 1958. The Amaryllis Manual. MacMillian and Co., New 40:105-111. York. 20. Cothran, C. D. 1985. Quest for large, yellow hippeastrums. Plant 37. Traub, H. P. and H. N. Moldenke. 1949. Amaryllidaceae: Tribe Life 41:34-35. Amarylleae. American Plant Life Society. 21. Doran, J. L. 1982. Observations of Hippeastrum species hybrids. 38. Williams, M. 1980. Self-sterility in Hippeastrum (Amaryllis) species. Amaryllis Bui. 2:42. Amaryllis Bui. 1:20. 22. Flory, W. S. and R. F. Coulthard, Jr. 1981. New chromosome counts, 39. Wilson, M. C. 1981. Amaryllis hybrids in J. L. Doran. Plant Life 37:109-110. numbers and types in genus Amaryllis. Plant Life 37:43-56. Proc. Fla. State Hort. Soc. 101:288-290. 1988. EFFECT OF TEMPERATURE AND DESICCATION ON THE GERMINATION OF THRINAX MORRISII William J. Carpenter and Edward F. Gilman University of Florida, IFAS Thrinax morrisii H. Wendl., the key thatch palm, is a Ornamental Horticulture Department slender fan palm native of southern Florida and the West Indies (Fig. 1). It is one of Florida's native palms frequently Additional index words, palm seed germination, key thatch used in landscapes and, until recently, has been moved palm, seed storage and handling. from natural to urban locations for this purpose. It is in cluded on the list of Florida's threatened indigenous plants Abstract. Temperature was found to control the germination (11). Recent legislation protecting palm habitats has of Thrinax morrisii H. Wendl the key thatch palm. At constant created interest in nursery propagation by seed. Limited temperatures the seeds have a narrow temperature range, seed germination research has been conducted using this with 69% germination at 35°C and 29, 21 and 30% at 40°, genera. Rees (9) reported 63% germination of Coccothrinax 30° and 25° respectively. Maximum germination of 86 and argentata in 30 days and Basu and Mukherjee (1) germi 81% resulted from alternating temperatures at 12-hour inter nated Thrinax parvifolia seed in 99 days, but failed to report vals between 25°-35° and 30°-40°. Temperatures at 35° prom the germination percentage. Research with other palm oted 50% of final germination in 51 days while alternating species has resulted in general recommendations for seed and other constant temperatures required 59 to 74 days. germination. Seed soaking for 24 to 72 hours prior to Seeds retained viability in storage under high levels of mois propagation has been found to shorten the days required ture and temperature stress. No changes in total germination for germination (7,8). Failure to remove the fleshy or days to 50% of final germination occurred until seed mois pericarp from palm seeds has delayed and caused irregular ture contents declined below 7%. Seeds stored 3 weeks at 5° germination (2,10). Maintaining relatively high germina to —10° had no reduction in total germination or rate of ger tion medium temperatures from 25° to 35° C has promoted mination. These results indicate that long-term storage of seed germination (3,7). The purpose of this research was seeds at low moisture contents and temperatures should be to determine the effects of temperature and seed desicca possible. tion on the germination of Thrinax morrisii. 288 Proc. Fla. State Hort. Soc. 101: 1988. Thrinax morrisii after cooling. Germination counts for treatment replicates 100 were made weekly and data statistically analyzed by 90 Tukey's honestly significant difference test at the 5% level. Seed storage temperature. Temperature's effect on seed Z 80 viability was determined during seed storage. Seeds were O 70 divided into 100-seed lots and placed in 50-ml sealed, glass vials. Four vials were immersed in polyethylene glycol- 35°C <f 60 water v/v in controlled baths (5) for 21 days at 5°, 0°, -5°, and -10° and -20° C. Following cold treatment seeds were germinated in moist peatmoss in 10-cm petri dishes in 35° C incubators. Germination counts were made weekly and CC 40 data statistically analyzed by Tukey's honestly significant LU O 30 difference test at the 5% level. j|S 20 Results and Discussion 10 Alternating temperatures 25°-35° and 30°-40° C prom oted the highest percentages of germination (Table 1), 0 while germination at constant 35° was significantly higher 01 23456789 10 11 121314 than 25°, 30° and 40° C (Fig. 2). These results are in agree ment with Hartmann and Kester (6) that fluctuating day- WEEKS night temperatures increase seed germination, with op timum diurnal variations at 10° C. At 35°, 69% of seeds Figure 1. Influence on constant 25°, 30°, 35° and 40° C temperatures on seed germination. germinated in 14 weeks and 50% of final germination was achieved in 51 days (Table 1). Although alternating tem peratures gave higher percentages of germination, days to 50% germination were lengthened to 60 and 62 days. Con Materials and Methods stant 25°, 30° and 40° C germination temperatures re- Standard procedures. Seeds of T. morrisii were received from a Florida seed wholesaler shortly after harvest, and all experiments were conducted using seed from the same lot. Seeds were stored at 5° C and 45% RH when necessary prior to beginning an experiment. Germination tests were conducted in incubators in the dark at constant or alternat ing 12-hour temperatures. Four replicates of all treatments were germinated in 10-cm petri dishes, each containing 100 seeds placed in moist Canadian peatmoss and kept moist by adding deionized water. A seed was considered germinated when the radicle visibly protruded through the testa. Total percent germination and mean days to 50% germination, an expression of germination rate, were cal culated according to the formula of Furutani (4). Germination temperatures. Seeds were soaked in deionized water 24 hours, surface dried, and dusted with Captan before planting in moist peatmoss in petri dishes. Treatments of 400 seeds were placed in incubators at con stant 25°, 30°, 35°, 40°, and alternating 25°-35° and 30°-40° C at 12-hour intervals. Germination counts were made weekly and treatment cumulative germination percentages and days required to 50% of final germination were calcu lated. The experiment was a single factor design using standard error (SE) to report variability around treatment means. Seed moisture content. The four replicates of 100 seeds for each treatment were weighed and placed in open petri dishes in 40° C drying ovens for 0, 6, 12, 24, 48, and 72 hours. Following dehydration, seeds were reweighed and immediately sealed in screw-capped 50-ml glass vials, 100 seeds per vial. Following 2 weeks storage, desiccated 100- seed replicates were reweighed, soaked in deionized water 24 hours and germinated in constant 35° C incubators in 10-cm petri dishes containing moist peatmoss. The initial total water content was determined by weighing four 100- Figure 2.