Reaction of Three Bromeliads to High Humidity During Storage

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University of Florida
Central Florida Research and Education Center-Apopka
CFREC-Apopka Research Report RH-92-26

R.T. Poole and C.A. Conover*

Bromeliads are relatively easy to grow specimen plants that provide a long period of effective display when placed in interior environments. Central Florida producers think bromeliads could command a bigger share of the foliage plant market if certain shipping problems were eliminated. During shipping, healthy leaf tissue sometimes develops necrosis on some or all plants within a shipment. Necrosis most often occurs at structurally weak points such as the arched area of the leaf.

Several experiments have been conducted over the past few years in an effort discover the production or shipping conditions which lead to this damage. In most experiments damage was not produced under test conditions. In the following two experiments, damage was produced on one of three bromeliads tested from the genus Aechmea.

Experiment 1 was a 2 x 2 factorial test with 2 replications per treatment initiated on 12 July 1992. Two local growers supplied a number of excellent quality ready-for-sale Aechmea 'Friederike' and Aechmea fasciata 'Morgana' to CFREC-Apopka. Excellent quality ready-for-sale Aechmea fasciata was obtained from two other local sources. Plants were placed in a greenhouse where maximum light intensity at plant level was 2000 ft-c and air temperatures ranged from 70 to 90°F.

On 16 July 1992, plants were sleeved, boxed and moved to dark air-tight coolers where air temperature was 65°F and relative humidity (RH) was either 90% ± 10% or 50% ± 10%. Plants were watered either three hours or three days before storage. Center vases and foliage of bromeliads watered three days before storage treatments began had dried when plants were placed in coolers. Vases of bromeliads watered three hours before storage were emptied when plants were sleeved and boxed although foliage was still wet. Leaves were checked for signs of developing necrosis after two hours, one day and three days in storage coolers.

Experiment 2, a 2 x 2 factorial test with 3 replications per treatment, was initiated on 30 July 1992. Locally grown ready-for sale Aechmea 'Friederike' and Aechmea fasciata 'Morgana' were given the same greenhouse, irrigation and cooler treatments as plants used in experiment 1. Plants were sleeved, boxed and placed in 65°F coolers on 3 August and moved back to the greenhouse on 6 August 1992. As in experiment 1, number of necrotic leaves was counted two hours, one day and three days after storage began.

Results of the two experiments were similar. Aechmea fasciata 'Morgana' and Aechmea fasciata were not affected by test treatments of pre-storage irrigation or storage humidity. High RH (90% ± 10%) during 65F dark storage damaged leaves of Aechmea 'Friederike' (Table 1). In experiment 1, few necrotic leaves were detected after two hours storage. Aechmea 'Friederike' plants with more necrotic leaves after three days in coolers were those in high humidity or watered three hours before storage.

In experiment 2, necrotic areas were detected on foliage within two hours of placement in coolers. When number of necrotic leaves were determined again after three days of storage, numbers had increased only slightly from when first counted.

Growers report that locally shipped plants in transit for two hours or less sometimes develop the same type of necrosis as produced in these experiments. A combination of wet plants or high air temperature and inadequate ventilation around plants in transit could quickly create a very humid environment. Results of these experiments indicate lower humidity during shipping could be beneficial for Aechmea 'Friederike'.

*Professor of Plant Physiology and Center Director and Professor of Environmental Horticulture, respectively, Central Florida Research and Education Center-Apopka, 2807 Binion Road, Apopka, FL 32703-8504.

Table 1. Irrigation treatment and humidity during storage influence number of necrotic leaves on Aechmea 'Friederike' grown at two local nurseries, then stored in 65°F dark coolers for three days.^z

^zBromeliads were stored from 16 July until 20 July 1992 during experiment 1 and from 3 Aug until 7 August 1992 during experiment 2.
^yPlants were watered 3 days before or 3 hours before being moved to 65°F dark coolers where relative humidity (RH) was 50% ± 10% or 90% ± 10%.