Drought stress during shipping and retailing reduces the postproduction quality and marketability of potted plants. Plants respond to drought stress by closing their stomata and reducing transpirational water loss. This stress response is mediated by the plant hormone abscisic acid (ABA). Exogenous applications of s-abscisic acid (s-ABA), the biologically active form of the hormone, can enhance drought tolerance and extend shelf life in a variety of bedding plants. However, little is known about the effectiveness of s-ABA at enhancing drought tolerance in perennial crops like chrysanthemum (Chrysanthemum ×morifolium). ‘Festive Ursula’ chrysanthemum plants were drenched (0, 125, 250, or 500 mg·L−1) or sprayed (0, 500, or 1000 mg·L−1) with s-ABA. All applications containing s-ABA effectively delayed wilting by reducing stomatal conductance (gS). Shelf life was extended from 1.2 to 4.0 days depending on the concentration of s-ABA. Spray applications of 500 mg·L−1 s-ABA to six additional chrysanthemum cultivars increased shelf life from 1.6 to 3.8 days following drought stress. s-ABA treatment also allowed severely drought-stressed chrysanthemums to recover and remain marketable after rewatering. Growers can treat chrysanthemums with s-ABA to reduce water use during shipping and to delay wilting if plants are not adequately watered during retailing.
Water stress during shipping and retailing reduces the postproduction quality and marketability of bedding plants. Antitranspirants can temporarily prevent plants from wilting by either physically blocking stomata or physiologically inducing stomatal closure, limiting transpirational water loss from leaves. The goal of this research was to evaluate the efficacy of commercially available antitranspirants on enhancing temporary water stress tolerance in bedding plants. Two physical antitranspirants [β-pinene polymer (βP) and vinyl-acrylic polymer (VP)], and three physiological antitranspirants [two sugar alcohol-based compounds (SACs) and a biologically active form of abscisic acid (s-ABA)] were applied to begonia (Begonia semperflorens-cultorum), new guinea impatiens (Impatiens hawkeri), impatiens (Impatiens walleriana), petunia (Petunia ×hybrida), african marigold (Tagetes erecta), and french marigold (Tagetes patula). Physical antitranspirants were sprayed on foliage and physiological antitranspirants were drenched to the media. All antitranspirants were applied at half (0.5×), equal to (1×), or twice (2×) the manufacturer’s recommended rate. Extended shelf life was observed when βP or s-ABA was applied. Treatment with βP increased the shelf life of impatiens and african marigold by 1 and 1.3 days compared with control plants, respectively. The application of βP at 2× was more effective at delaying visual wilting than at lower rates (0.5× and 1×) in african marigold. Applications of s-ABA delayed wilting by 1.3 to 3.7 days in all tested cultivars. The shelf lives of impatiens and petunia treated with s-ABA at 2× were extended the most by 3.7 and 3.0 days compared with control plants, respectively. A rapid reduction of stomatal conductance (gS) was observed within 4 hours of βP or s-ABA application in plants showing delayed wilting symptoms. s-ABA treatment appeared to cause marginal leaf chlorosis in impatiens, whereas application of βP damaged the opened flowers in all tested cultivars. The application of VP or SACs did not extend shelf life in any treated plants. These results suggest that foliar application of βP on selected species and treatment with s-ABA on most of species would allow bedding plants to withstand water deficit during shipping and/or retailing.