Evaluation of Antitranspirants for Enhancing Temporary Water Stress Tolerance in Bedding Plants

摘要

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 [beta-pinene polymer (beta P) 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 xhybrida), africanmarigold (Tagetes erecta), and frenchmarigold (Tagetes patula). Physical antitranspirants were sprayed on foliage and physiological antitrans-pirants were drenched to the media. All antitranspirants were applied at half (0.5x), equal to (1x), or twice (2x) the manufacturer's recommended rate. Extended shelf life was observed when bP or s-ABA was applied. Treatment with bP increased the shelf life of impatiens and african marigold by 1 and 1.3 days compared with control plants, respectively. The application of bP at 2x was more effective at delaying visual wilting than at lower rates (0.5 x and 1x) 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 2x were extended the most by 3.7 and 3.0 days compared with control plants, respectively. A rapid reduction of stomatal conductance (g(S)) was observed within 4 hours of bP or s-ABA application in plants showing delayed wilting symptoms. s-ABA treatment appeared to cause marginal leaf chlorosis in impatiens, whereas application of bP 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 bP 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.