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Chilling Injury in Tropical Foliage Plants: II. Aglaonema 1
Jianjun Chen, Richard W. Henley, Richard J. Henny, Russell D. Caldwell, and Cynthia A. Robinson2Aglaonema, commonly called Chinese Evergreen, is a member of the family Araceae and comprises 21 known species that are native to southeast Asia where they grow in the humid, heavily shaded tropical forest (Huxley, 1994). Cultivated in the East for centuries, Aglaonema was believed to bring fortune to life and probably was introduced to the western world in 1885 (Brown, 2000). Currently, Aglaonema are among the most popular tropical ornamental foliage plants because of the attractive foliar variegation, low light and humidity tolerances, and few pest problems.
A major limitation in the production of Aglaonema is chilling injury when plants are exposed to temperatures from just above 32°F to 59°F (Chen, et al., 2001; Fooshee and McConnell, 1987; Henley, et al., 1998; Hummel and Henny, 1986). Chilling injury to Aglaonema may also occur during shipment, retail display, and interior decoration (Blessington and Collins, 1993; Griffith, 1998; Joiner, 1981).
With recently increased release of Aglaonema cultivars, hybrids with different variegation patterns, showy petiole and stem colors, and varying growth habits have become available (Cialone, 2000). However, the response of these new cultivars to chilling temperatures is largely unknown. This report intends to summarize chilling injury symptoms in Aglaonema and cultivar differences in resistance to chilling temperatures.
Twelve Aglaonema cultivars were grown in 8" pots under greenhouse conditions. After attaining marketable sizes, these plants were chilled at 35°, 45°, and 55°F for 24 hours in walk-in coolers. Chilling injury symptoms were characterized and percentages of injured leaves were determined daily for the next 10 days. Since Aglanomena's aesthetic appearance is directly related to foliage color and quality, any damage on leaves, regardless of severity, can greatly reduce its ornamental value in the market place (Chen, et al., 1998; Henley, et al., 1998). Therefore, the percentage of injured leaves was the primary parameter used to determine the sensitivity of cultivars to chilling temperatures.
Chilling Injury in Aglaonema
Dark and greasy patches appeared between midvein and leaf margin on the upper surface of leaves two days after chilling at 35°, 45°, or 55°F. Injured areas or individual patches were irregular, varying from 10% to 80% of the entire leaf area. If injured areas totaled less than 40%, leaves could stay alive for months; whereas if more than 40%, leaves could became yellow and finally abscised. The number of leaves injured continuously increased for up to 10 days, but no further injured leaves appeared 10 days later.Leaves of different maturity expressed dissimilar responses to chilling temperatures. Mature and old leaves appeared to be much more sensitive to chilling than young leaves. Among the injured leaf totals, mature leaf injury ranged from 45% to 100% and old leaves from 14% to 53%, but young leaf injury was only 0% to 6% depending on cultivar (Table 1).
Table 1. Percentages of leaf injury categorized by leaf maturityz 10 days after 24-hour chilling at 35°F.
Leaf maturity
Cultivar Young
Mature
Old
Emerald Star 0.0
0.0
0.0
Stars 0.0
0.0
0.0
Jewel of India 0.0
0.0
0.0
Black Lance 0.0
100.0
0.0
Maria 0.0
66.6
33.4
Green Lady
1.0
46.6
52.4
Green Majesty 0.0
60.2
39.8
Royal Queen 0.0
46.9
53.1
Moonshine 2.5
50.1
47.4
Silver Queen 4.7
54.4
40.9
Manila Pride 0.0
85.6
14.4
Silver Frost 6.5
45.4
48.1
zYoung: the most recently fully expanded leaves up to and including the newest unfurled leaf; mature: leaves immediately below the young leaves down to the old leaves; and old: about three to four basal leaves. The sum of the percentage of injured young, mature, and old leaves equals to 100%.
Cultivar Differences in Chilling Resistance
Cultivars were significantly different in resistance to chilling temperatures (Table 2). 'Silver Queen', one of the most popular cultivars in the foliage plant industry, was extremely sensitive to chilling, with 30, 43, and 68% of leaves injured at 55°, 45°, and 35°F 10 days after chilling. 'Maria', a cultivar well known for its chilling resistance, was not the most resistant one tested. Ten days after chilling at 35°F, 32% of 'Maria's' leaves were injured, but there was no discernable injury on 'Emerald Star', 'Stars', or 'Jewel of India'. 'Emerald Star', 'Stars', and 'Jewel of India' were the most chilling resistant cultivars. In addition, 'Black Lance' and 'Green Lady' appeared to be slightly better than or at least equal to 'Maria' in chilling resistance. Cultivation of the resistant cultivars will reduce chilling injury and energy used for heating during production.Table 2. Percentages of injured leaves of 12 Aglaonema cultivars 10 days after 24-hour chilling at 35°F, 45°F, or 55°F.
Chilling temperature
Cultivar 35°F
45°F
55°F
Emerald Star 0.0
0.0
0.0
Stars 0.0
0.0
0.0
Jewel of India 0.0
0.0
0.0
Black Lance 18.3
12.0
0.0
Maria 32.0
8.3
0.0
Green Lady 34.0
9.0
0.0
Green Majesty 50.0
17.3
4.7
Royal Queen 51.0
34.1
14.0
Moonshine 54.0
10.0
2.0
Silver Queen 68.3
37.7
29.7
Manila Pride 73.0
15.3
13.3
Silver Frost 80.0
4.7
0.0
Cultivars also differ in their sensitivity to critical chilling temperature, i. e. a temperature at which chilling injury occurs (Table 2). For example, 10 days after chilling, 'Silver Frost' had no injury at 55°F and only 5% leaf injury at 45°F, but 80% of the leaves were injured when exposed to 35°F. A similar pattern occurred in 'Maria' and 'Green Lady'. In contrast, 'Silver Queen' and 'Royal Queen' had 30% and 14% injured leaves, respectively, 10 days after chilling at 55°F. Implications are that critical chilling temperatures of 'Silver Frost', 'Maria', and 'Green Lady' are around 45°F, whereas critical temperatures of 'Silver Queen' and 'Royal Queen' are above 55°F. Critical chilling temperature distinctions are potentially important in Aglaonema production because growers will be able to manage their greenhouse temperatures based on cultivar-dependent chilling temperature sensitivity ranges.
In summary, chilling injury in Aglaonema was characterized by dark and greasy-appearing patches on injured leaves. Young leaves appeared to be more resistant to chilling temperatures than either mature or old leaves. Significant chilling resistance exists among Aglaonema cultivars, a genus considered extremely sensitive to chilling temperatures. 'Emerald Star', 'Stars', and 'Jewel of India' withstood exposure to 35°F without injury, whereas 'Silver Queen' was injured at 55°F. In addition, cultivars differed in their sensitivity to critical chilling temperatures. Use of resistant cultivars may greatly reduce the chance of chilling injury during production and transportation and also conserve energy used for greenhouse heating. However, if chilling-sensitive cultivars must be grown, greenhouse facilities should allow for maintaining temperature above 60°F.
Literature Cited
Blessington, T.M. and Collons, P.C. 1993. Foliage Plants: Prolonged Quality, Postproduction Care and Handling. Ball Publishing, Batavia, IL.Brown, D. 2000. Aroids: Plants of the Arum Family. Second Edition. Timber Press. Portland. OR.
Chen, J., Henley, R.W., Henny, R.J., Caldwell, R.D., and Robinson, C.A. 1998. A simple leaf-assay method for evaluating Aglaonema sensitivity to chilling temperatures. Proc. Fla. State Hort. Soc. 111:43-46.
Chen, J., Henny, R.J., McConnell, D.B., and Nell, T.A. 2001. Cultivar differences in interior performances of acclimatized foliage plants. Acta Horticulturae 543:135-140.
Cialone, J. 2000. New Chinese evergreen cultivars for the interiorscape. Ohio Florists' Assoc. Bull. No. 847:1, 9-10.
Fooshee, W.C. and McConnell, D.B. 1987. Response of Aglaonema 'Silver Queen' to nighttime chilling temperatures. HortScience 22:254-255.
Griffith, L.P. 1998. Tropical Foliage Plants: A Grower's Guide. Ball Publishing, Batavia, IL.
Henley, R.W., Henny, R.J., and Chen, J. 1998. Chilling injury on twenty Aglaonema Cultivars. Proc. Southern Nursery Assoc. Conf. 43:117-121.
Hummel, R.L. and Henny, R.J. 1986. Variation in sensitivity to chilling injury within the genus Aglaonema. HortScience 21:291-293.
Huxley, A. 1994. The New Royal Horticultural Society Dictionary of Gardening. The Macmillon Press Ltd, London.
Joiner, J.N. 1981. Foliage Plant Production. Prentice-Hall, Englewood Cliffs, NJ.
Table 1. Percentages of leaf injury categorized by leaf maturityz 10 days after 24-hour chilling at 35°F.
Leaf maturity
Cultivar Young
Mature
Old
Emerald Star 0.0
0.0
0.0
Stars 0.0
0.0
0.0
Jewel of India 0.0
0.0
0.0
Black Lance 0.0
100.0
0.0
Maria 0.0
66.6
33.4
Green Lady
1.0
46.6
52.4
Green Majesty 0.0
60.2
39.8
Royal Queen 0.0
46.9
53.1
Moonshine 2.5
50.1
47.4
Silver Queen 4.7
54.4
40.9
Manila Pride 0.0
85.6
14.4
Silver Frost 6.5
45.4
48.1
zYoung: the most recently fully expanded leaves up to and including the newest unfurled leaf; mature: leaves immediately below the young leaves down to the old leaves; and old: about three to four basal leaves. The sum of the percentage of injured young, mature, and old leaves equals to 100%.
Table 2. Percentages of injured leaves of 12 Aglaonema cultivars 10 days after 24-hour chilling at 35°F, 45°F, or 55°F.
Chilling temperature
Cultivar 35°F
45°F
55°F
Emerald Star 0.0
0.0
0.0
Stars 0.0
0.0
0.0
Jewel of India 0.0
0.0
0.0
Black Lance 18.3
12.0
0.0
Maria 32.0
8.3
0.0
Green Lady 34.0
9.0
0.0
Green Majesty 50.0
17.3
4.7
Royal Queen 51.0
34.1
14.0
Moonshine 54.0
10.0
2.0
Silver Queen 68.3
37.7
29.7
Manila Pride 73.0
15.3
13.3
Silver Frost 80.0
4.7
0.0
Footnotes
1. This document is ENH843, a series of the Environmental Horticulture Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Science, University of Florida. First published: October 2001. Reviewed: May 2008. Please visit the EDIS website at http://edis.ifas.ufl.edu2. Jianjun Chen, Assistant Professor, Plant Physiologist; Richard W. Henley, Professor Emeritus; Richard J. Henny, Professor, Plant Geneticist; Russell D. Caldwell, Biological Scientist; and Cynthia A. Robinson, former Biological Scientist at the University of Florida, Institute of Food and Agricultural Sciences, Environmental Horticulture Department and Mid-Florida Research and Education Center, Apopka, FL 32703.
The authors appreciate the Sunshine Foliage World, Zolfo Springs, FL and the Butler's Nursery, Miami, FL for providing initial plant materials, and also Verlite Co., Tampa, FL for providing Vergo Container Mix A.
The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.
U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.
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