Abscisic Acid Application Enhances Drought Stress Tolerance in Bedding Plants

Abstract

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.

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

“…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). We observed leaf chlorosis on droughtstressed Tagetes patula (marigolds), Pelargonium ·hortorum (seed geraniums), and pansies treated with drench or spray applications of s-ABA.…”

“…We observed leaf chlorosis on droughtstressed Tagetes patula (marigolds), Pelargonium ·hortorum (seed geraniums), and pansies treated with drench or spray applications of s-ABA. Leaf chlorosis in pansies was not directly induced by drought treatment, because symptoms were observed in both watered and drought-stressed plants that were treated with s-ABA (Waterland et al, 2010). It is unclear why s-ABA induced leaf chlorosis and senescence in pansies or how this side effect might be prevented.…”

“…Under severe and moderate drought stress, Petunia ·hybrida (petunia) show an increase in ethylene production as well as an increase in s-ABA, the biologically active form of ABA (Vardi and Mayak, 1989). Changes in the balance of ABA, ethylene, gibberellins, and cytokinins within the plant may be responsible for the development of leaf senescence (Blanchard et al, 2007;Waterland et al, 2010) and leaf abscission (Kim and van Iersel, 2008) after s-ABA applications.…”

“…The goal of this research was to determine how to prevent s-ABA-induced leaf chlorosis in pansy and viola. Although s-ABA applications allow pansies to survive temporary periods of drought stress, negative side effects like leaf chlorosis decrease overall crop quality (Waterland et al, 2010). Our specific objectives were 1) to determine if cultivar, developmental stage, method of application, and concentration influence the effectiveness of s-ABA and the occurrence of leaf chlorosis symptoms; 2) to identify an application method and/or concentration of s-ABA that would not induce leaf chlorosis; and 3) to determine whether s-ABA-induced leaf chlorosis can be prevented by the application of other PGRs, including cytokinins, gibberellins, or ethylene perception inhibitors.…”

Effects of UV radiation on growth and postharvest characteristics of three pot rose cultivars grown at different altitudes

“…Ornamentals are mainly grown in protected cultivation systems and the environmental conditions during growth such as light (Mortensen and Gislerød, 1999;Fjeld et al, 1994), day and night temperatures (Moe, 1975;Hamrick, 2003), carbon dioxide levels (Dole and Wilkins, 2005) and relative air humidity Pettersen et al, 2007;Fanourakis et al, 2012) are all shown to affect the postharvest shelf life (for review see, Mayak, 1979a, 1979b). Stomatal behavior and water relations are one of the main factors determining the potential postharvest life, especially for cut flowers, but also for some pot and bedding plants ; van Doorn, 1997;Waterland et al, 2010aWaterland et al, , 2010b. Studies have shown that the stomatal behavior in response to conditions of the cultivation environment, such as relative air humidity Fanourakis et al, 2012), light quality , and photoperiod (Mortensen and Gislerød, 1999), will persist also after harvest.…”