Evaluation of Abscisic Acid Analogs as Holding Agents for Bedding Plant Seedlings

Drought stress is a major cause of postproduction decline in bedding plants. The plant hormone abscisic acid (ABA) regulates drought stress responses by mediating stomatal closure, thereby reducing transpirational water loss. Exogenous ABA applications delay wilting and allow plants to survive short periods of severe drought. The effectiveness of the ABA biochemical, s-ABA (ConTegoä; Valent BioSciences Corp., Libertyville, IL), at delaying wilting and extending shelf life during drought stress was evaluated in six bedding plant species. Spray and drench applications of 0 or 500 mgÁL -1 s-ABA were applied to Impatiens walleriana (impatiens), Pelargonium ·hortorum (seed geranium), Petunia ·hybrida (petunia), Tagetes patula (marigold), Salvia splendens (salvia), and Viola ·wittrockiana (pansy). Water was subsequently withheld and wilting symptoms were compared between treated and control plants. s-ABA applications delayed wilting in all crops by 1.7 to 4.3 days. Leaf chlorosis was observed after s-ABA application in drought-stressed seed geraniums, marigolds, and pansies. In seed geraniums and marigolds, the drought stress itself resulted in leaf chlorosis that was equivalent to or more severe than the s-ABA application alone. In pansies, s-ABA applications induced leaf chlorosis that was more severe than the drought treatment. Overall, s-ABA was consistently effective at reducing water loss and extending shelf life for all species treated. Applications of s-ABA to bedding plants before shipping and retailing would allow plants to maintain marketability even under severe drought stress conditions.

Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Abscisic Acid Application Enhances Drought Stress Tolerance in Bedding Plants

Waterland¹,

Campbell²,

Finer³

et al. 2010

“…The exogenous application of ABA or ABA analogs delays drought stress-induced wilting in a variety of bedding and potted plants (Blanchard et al, 2007;Kim and van Iersel, 2008;Monteiro et al, 2001;Sharma et al, 2005Sharma et al, , 2006Waterland et al, 2010). Although ABA applications allow plants to survive temporary periods of drought stress, negative side effects, including leaf necrosis, chlorosis, or abscission, have been observed in some species (Blanchard et al, 2007;Kim and van Iersel, 2008;Waterland et al, 2010).…”

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confidence: 99%

Benzyladenine and Gibberellic Acid Application Prevents Abscisic Acid-induced Leaf Chlorosis in Pansy and Viola

Waterland¹,

Finer²,

Jones³

2010

Drought stress during the shipping and retailing of floriculture crops can reduce postproduction shelf life and marketability. The plant hormone abscisic acid (ABA) mediates drought stress responses by closing stomata and reducing water loss. Applications of exogenous s-ABA effectively reduce water loss and allow a variety of species to survive temporary periods of drought stress. Unfortunately, s-ABA application can also lead to leaf chlorosis, which reduces the overall quality of economically important bedding plant species, including Viola ·wittrockiana (pansy). The goal of this research was to determine how to prevent s-ABA-induced leaf chlorosis in pansy and a closely related species, Viola cornuta (viola). All concentrations of both spray (250 or 500 mgÁL -1 ) and drench (125 or 250 mgÁL -1 ) s-ABA applications induced leaf yellowing. Young plants at the plug stage and 11-cm finished plants with one to two open flowers were further evaluated to determine if the developmental stage of the plants influenced s-ABA effectiveness or the development of negative side effects. Both plugs and finished pansies and violas developed leaf chlorosis after s-ABA applications, but symptoms were generally more severe in finished plants. The individual application of benzyladenine (BA), gibberellic acid (GA 4+7 ), or the ethylene perception inhibitor, 1-methylcyclopropene, before s-ABA application had no effect on the development of s-ABA-induced leaf chlorosis. However, applications of 5 or 10 mgÁL -1 BA and GA 4+7 as a mixture (BA + GA 4+7 ) before a drench or spray application of s-ABA prevented leaf chlorosis. The application of s-ABA and BA + GA 4+7 would allow floriculture crops to tolerate temporary periods of drought stress without any loss of postproduction quality.

“…Inadequate watering during retail diminishes the salability and shelf life of plants (Armitage, 1983), resulting in economic losses for growers and/or retailers. One way to reduce water use and extend the shelf life of plants in retail settings is by the application of exogenous ABA (Barrett and Campbell, 2006), although the duration of the effects is dependent on species, application rate, and application method (Blanchard et al, 2007;Kim and van Iersel, 2011;Sharma et al, 2006;van Iersel et al, 2009;Waterland et al, 2010aWaterland et al, , 2010b. The effects of ABA can be profound and have commercial implications.…”

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confidence: 99%

“…We conducted two studies to quantify the effects of ABA drenches on tomato. Tomatoes were used as the model crop because they are responsive to ABA applications (Sharma et al, 2006). The objectives of the first study were to evaluate the effects of exogenous ABA on the ET of drought-stressed and well-watered tomatoes and to quantify how ABA affects the time to wilting.…”

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confidence: 99%

Determining the Effects of Abscisic Acid Drenches on Evapotranspiration and Leaf Gas Exchange of Tomato

Astacio¹,

Iersel²

2011

It is common for plants in the retail market to receive inadequate water and lose aesthetic value within a short period of time. The plant hormone abscisic acid (ABA) is naturally produced in response to drought conditions and reduces transpiration (E) by closing the stomata. Thus, ABA may lengthen shelf life of retail plants by reducing water loss. Two studies were conducted to look at effects of ABA on plant water use and shelf life over a 13-day period and short-term effects of ABA on leaf physiology. The objective of the short-term study was to determine how quickly 100-mL drenches of 250 mg·L−1 ABA solution affect leaf gas exchange of tomatoes (Solanum lycopersicum ‘Supersweet 100’). ABA drenches reduced stomatal conductance (gS), E, and photosynthetic rate (Pn) within 60 min. After 2 h, E, gs, and Pn were reduced by 66%, 72%, and 55% respectively, compared with the control plants. In the13-day study, ABA was applied to tomatoes as a 100-mL drench at concentrations ranging from 0 to 1000 mg·L−1 and ABA effects on water use and time to wilting were quantified. Half of the plants were not watered after ABA application, whereas the other plants were watered as needed. In general, higher ABA concentrations resulted in less water use by both well-watered and unwatered plants. ABA delayed wilting of unwatered plants by 2 to 8 days (dependent on the dose) as compared with control plants. In well-watered plants, ABA reduced daily evapotranspiration (ET) for 5 days, after which there were no further ABA effects. Negative side effects of the ABA application were rate-dependent chlorosis of the lower leaves followed by leaf abscission. These studies demonstrate that ABA drenches rapidly close stomata, limit transpirational water loss, and can extend the shelf life of retail plants by up to 8 days, which exemplifies its potential as a commercially applied plant growth regulator.