Effects of Low Temperature Storage on Quality of Twenty-two Foliage Plants

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R.T. Poole, Ph.D. and C.A. Conover, Ph.D.*
University of Florida
Central Florida Research and Education Center-Apopka

CFREC-Apopka Research Report RH-93-6

Summary

When twenty-two foliage plants were stored in dark, air tight coolers for up to four days at 36, 41 or 46°F air temperatures quality of seven plants (Araucaria heterophylla, Dizygotheca elegantissima, Ficus benjamina, Maranta leuconeura 'Kerchoviana', Rademachera sinica, Schefflera arboricola and Syngonium podophyllum 'White Butterfly') was unaffected. Chilling injury symptoms on foliage resulting from low temperature storage are summarized in Table 1.

Storage duration and storage air temperature interactions damaged foliage of twelve plants, Aglaonema 'Silver Queen', Chamaedorea elegans, Chrysalidocarpus lutescens, Codiaeum variegatum 'Norma', Dieffenbachia maculata 'Camille', Dracaena marginata, Epipremnum aureum 'Marble Queen', Ficus elastica 'Robusta', Homalomena 'Emerald Gem', Nephrolepis exaltata 'Bostoniensis Compacta', Philodendron scandens oxycardium and Spathiphyllum 'Petite' Generally, damage worsened as storage temperature decreased and storage time increased.

Dracaena deremensis 'Janet Craig' quality deteriorated when storage duration increased or air temperature decreased. Dracaena deremensis 'Warneckii' and Neoregelia carolinae 'Perfecta Tricolor' foliage was damaged by 36°F air temperature during storage.

On two plants, Dracaena marginata and Spathiphyllum, no damage was visible five days after treatment but foliage damage was apparent when plants were graded a second time two weeks after removal from coolers.

Introduction

Many foliage plants are injured when exposed to air temperatures between 35°F and 50°F during propagation, production, storage or shipping. Damage, commonly called chilling injury, typically becomes more severe with lower temperature and also as exposure time increases (Lyons, 1973; Marousky, 1980; Marousky and Harbaugh, 1978; McConnell, et al, 1978; McConnell et al, 1982; McWilliams and Smith, 1978; Poole and Conover, 1983). Some common symptoms are surface lesions on foliage, water soaked tissue that eventually turns black and necrotic, tissue breakdown and reduced growth rates (Morris, 1982; Ingram et al, 1978). Since symptoms may be similar to other plant disorders, and damage sometimes does not become apparent until two to four days after removal from low temperature conditions, more work needs to be done to determine chilling tolerance of economically important foliage plants (Conover, 1980; Marousky 1980). The following test was initiated to determine effects of low air temperature during short-term shipping on twenty-two foliage plants.

Materials and Methods

The following twenty-two foliage plants were obtained from local growers; Aglaonema 'Silver Queen' (Silver Queen aglaonema), Araucaria heterophylla (Norfolk Island pine), Chamaedorea elegans (parlor palm), Chrysalidocarpus lutescens (areca palm), Codiaeum variegatum 'Norma' (Norma croton),Dieffenbachia maculata 'Camille' (Camille dieffenbachia), Dizygotheca elegantissima (false aralia), Dracaena deremensis 'Janet Craig' Janet Craig dracaena), Dracaena deremensis 'Warneckii' (Warneckii dracaena), Dracaena marginata (Madagascar dragon tree), Epipremnum aureum 'Marble Queen' (Marble Queen pothos), Ficus benjamina (weeping fig), Ficus elastica 'Robusta' (robust rubber tree), Homalomena 'Emerald Gem', (Emerald Gem homalomena), Maranta leuconeura 'Kerchoviana' (prayer plant), Neoregelia carolinae 'Perfecta Tricolor' (Perfecta Tricolor blushing bromeliad), Nephrolepis exaltata 'Bostoniensis compacta' (compact Boston fern), Philodendron scandens oxycardium (heart-leaf philodendron), Rademachera sinica (China doll), Schefflera arboricola (dwarf schefflera), Spathiphyllum 'Petite' (Petite spathiphyllum) and Syngonium podophyllum 'White Butterfly' (White Butterfly nephthytis). Plants were excellent quality fully grown specimens produced in 4, 6 or 10-inch containers.

Depending on availability of quality specimens, plants were either stored for one, two, three or four days in dark airtight coolers where air temperature was 36, 41 or 46°F (a 3 x 4 factorial design with five foliage plants of each type tested per air temperature), or were stored for two or four days in airtight dark coolers in 36, 41 or 46°F air temperature (a 3 x 2 factorial design with five foliage plants of each type tested per air temperature).

Plants were acquired, stored and evaluated on various dates starting on January 13,1991 and ending on April 10, 1991. Experimental design was chosen for each kind of foliage plant based on available excellent quality specimens, so that five foliage plants were stored using two time periods and the remaining seventeen plants were tested using four storage time treatments.

Araucaria heterophylla, Chamaedorea elegans, Dieffenbachia maculata 'Camille', Dizygotheca elegantissima, Dracaena marginata, Ficus elastica 'Robusta', Neoregelia carolinae 'Perfecta Tricolor', Nephrolepis exaltata 'Bostoniensis compacta', Schefflera arboricola and Syngonium podophyllum 'White Butterfly' were placed in paper sleeves immediately before storage. Sleeves were removed when storage treatments were completed. Aglaonema 'Silver Queen', Chrysalidocarpus lutescens Codiaeum variegatum 'Norma', Dracaena deremensis 'Janet Craig' Dracaena deremensis 'Warneckii', Epipremnum aureum 'Marble Queen' Ficus benjamina, Homalomena 'Emerald Gem', Maranta leuconeura 'Kerchoviana', Philodendron scandens oxycardium, Rademachera sinica and Spathiphyllum 'Petite' were not sleeved during storage.

Before and after time spent in air-tight dark coolers, plants were maintained in different greenhouses so that favorable environmental conditions were provided for all types. Twenty foliage plant types were graded using a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair quality, salable, 4 = good quality and 5 = excellent quality. Norma croton quality was evaluated by counting the necrotic, dead and dying leaves. Plants with more than two leaves damaged were unsalable. Dracaena marginata cold damage was graded by rating size of the gray bands appearing in foliage (a typical sign of cold damage in Dracaena marginata) on a scale of 1 = no bands or damage, 2 = some grey streaking but little overall damage, 3 = plants noticeably damaged but still salable, 4 = gray bands at least 0.5 cm wide throughout foliage, plants unsalable and 5 = prominent gray bands 1 cm wide throughout foliage.

Plants were graded two times after removal from coolers. If damage was apparent when plants were removed from coolers, plants were immediately graded and the second evaluation was done two weeks later. When no damage was visible immediately after plants were stored, plants were graded five days and two weeks after removal from coolers.

Results

Six of the foliage plants, Araucaria heterophylla, Dizygotheca elegantissima, Ficus benjamina, Maranta leuconeura 'Kerchoviana', Schefflera arboricola and Syngonium podophyllum 'White Butterfly' were unaffected by storage treatments (Table 1). Quality of these plants two weeks after removal from storage was excellent. Although some leaves on Rademachera sinica developed necrotic tips after storage treatments, damage was insignificant and overall plant quality remained unaffected.

Interaction of storage time and storage air temperature had a negative affect on quality of ten foliage plants (Table 2). Chrysalidocarpus lutescens was damaged after two days storage in 36°F air temperature and Codiaeum variegatum 'Norma' and Spathiphyllum 'Petite' were damaged when stored three or four days at 36°F. However, none of these three foliage plants were injured by four days storage at 41 or 46°F.

Philodendron scandens oxycardium were damaged when stored for two or more days in 36°F air temperature. Foliage of plants stored for three or four days at 41°F also showed symptoms of chilling injury. Storage for two days at 41°F or four days at 46°F did not harm foliage.

Dracaena marginata, Epipremnum aureum 'Marble Queen' and Homalomena 'Emerald Gem' were not damaged when stored in 46°F coolers for four days. Severity of damage caused by storage at 36 or 41°F increased as temperature decreased and storage time increased.

Dieffenbachia maculata 'Camille' tolerated three days at 46°F or one day at 41°F without foliage damage. Plants stored at 36°F were injured regardless of storage duration.

Nephrolepis exaltata 'Compacta' ferns stored in 36 or 41°F air temperatures were injured, with the low temperature having the most severe effects. Ferns stored at 46°F for up to four days were not damaged.

Aglaonema 'Silver Queen' foliage showed symptoms of chilling injury at all the storage times and air temperatures tested. Injury was more severe as storage time increased and air temperature decreased. Damage resulted in low quality grades so that no Aglaonema 'Silver Queen' were salable two weeks after storage.

When Dracaena marginata and Spathiphyllum 'Petite' were examined five days after storage, plants did not appear to be negatively affected by any storage treatment. However, when evaluated a second time, two weeks after storage, foliage damage was apparent.

Dracaena deremensis 'Janet Craig', Dracaena deremensis 'Warneckii' and Neoregelia carolinae 'Perfecta Tricolor' were unaffected by interactions of storage air temperature and storage duration. However, both air temperature during storage and storage duration influenced plant grade of Dracaena deremensis 'Janet Craig' (Table 3). When quality was evaluated two weeks after storage, only plants at 41 and 46°F, or stored for one day were in salable condition.

Plant grades of Dracaena deremensis 'Warneckii' and Neoregelia carolinae 'Perfecta Tricolor' were influenced similarly by storage air temperatures (Table 4). Only storage at 36°F damaged plants. Neoregelia carolinae 'Perfecta Tricolor', although damaged, were still in salable condition but Dracaena deremensis 'Warneckii' too badly damaged to be considered salable.

Conclusion

As reported elsewhere, plant resistance to chilling injury varied depending on species (Lyons, 1973). Severity of damage on affected plants was greater as temperatures approached freezing and also increased with storage time. These findings are consistent with previous research with other foliage plants (Marousky, 1980; Marousky and Harbaugh, 1978; McConnell, et al, 1978; McConnell et al, 1982; McWilliams and Smith, 1978; Poole and Conover. 1983).

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*Professor of Plant Physiology, Professor of Environmental Horticulture and Center Director, respectively (retired 7/96), Central Florida Research and Education Center, 2807 Binion Road, Apopka, Florida 32703-8504.

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References

1. Conover, C.A. 1980. Maintaining foliage plant quality during truck transit. Florists' Rev. 165(4290):31, 69.
2. Ingram, D.L., D.B. McConnell, and T.J. Sheehan. 1978. Effects of chilling temperatures on container growth of Dieffenbachia 'Exotic Perfection' . Proc. S.N.A. Res. Conf. 23:39.
3. Lyons, J.M. 1973. Chilling injury in plants. Annu. Rev. Plant Physiol. 24:445-466.
4. Marousky, F.J. 1980. Chilling injury in Dracaena sanderana and Spathiphyllum 'Clevelandii'. HortScience 15:197-198.
5. Marousky, F.J. and B.K. Harbaugh. 1978. Deterioration of foliage plants during transit. Proc. Nat. Trop. Fol. Short Course p. 33-39.
6. McConnell, D.B., D.L. Ingram, C. Groga-Bada and T.J. Sheehan. 1982. Chilling injury of silvernerve plant. HortScience 17:819-820.
7. McConnell, D.B., D.L. Ingrain, C. Groga-Bada and T.J. Sheehan. 1978. Chilling effects on propagation of Dieffenbachia 'Exotica Perfection'. Fol. Dig. 4(4):3-5.
8. McWilliams, E.L. and C.W. Smith. 1978. Chilling injury in Scindapsus pictus, Aphelandra squarrosa, and Maranta leuconeura. HortScience 13- 179-l 80
9. Morris, L.L. 1982. Chilling injury of horticultural crops: an overview. HortScience 17:161162.
10. Poole, R.T. and C.A. Conover. 1983. Factors influencing chilling damage of foliage plants. Interiorscape 5(14):12-13.

Table 1. Date foliage plants were removed from temperature controlled coolers after one, two, three or four days of storage at 36, 41 or 46°F air temperature, dates plants were graded and description of chilling injury resulting from storage treatments.

^zPlants were graded based on a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair quality, salable, 4 = good quality and 5 = excellent quality. ^yPlants removed from coolers on March 13, 1992 were graded March 16, 1992 but damaged when a hailstorm destroyed greenhouses on March 25, 1992 so that plants could not be graded a second time.

Table 2. Interaction effects of low air temperatures and storage time on ten foliage plants.

^zPlants were graded on a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair quality, salable, 4 = good quality and 5 = excellent quality plants.
^yBad leaves were necrotic, dead and dying leaves.
^xCold damage graded by rating size of the gray bands appearing in foliage (a typical sign of cold damage in Dracaena marginata) on a scale of 1 = no bands or damage, 2 = some grey streaking but little overall damage, 3 = plants noticeably damaged but still salable, 4 = gray bands at least 0.5 cm wide throughout foliage, plants unsalable and 5 = prominent gray bands 1 cm wide throughout foliage.

Table 3. Plant grade of Dracaena deremensis 'Janet Craig' affected by low air temperatures or storage time.

^zPlants were graded based on a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair quality, salable, 4 = good quality and 5 = excellent quality. Y**; Results significant at P = 0.001.

Table 4. Effects of low air temperature during storage on Dracaena deremensis 'Warneckii' and Neoregelia carolinae 'Perfecta Tricolor'.

^zPlants were graded based on a scale of 1 = dead, 2 = poor quality, unsalable, 3 = fair quality, salable, 4 = good quality and 5 = excellent quality.
^yns, **; Results nonsignificant or significant at P = 0.001, respectively.