Assessing Tolerance to Sodium Chloride Salinity in Fourteen Floriculture Species

Abstract

The use of saline irrigation water may be inevitable in the future since the freshwater supply is decreasing over time. In some regions of the United States, producers of both ornamental and agronomic crops are already facing a limited supply of high-quality water. Therefore, it is necessary to determine the salt tolerance of commonly used greenhouse bedding plants to minimize potential salt damage before use of nonpotable water sources is mandated. Research screening several bedding plants has not taken place for more than two decades. Therefore, we undertook experiments to screen popular bedding plants for salt tolerance during greenhouse production. Transplants were exposed to 0 (control), 20, 40, 60, or 80 mm sodium chloride (NaCl) in the irrigation water for 5 weeks resulting in average substrate pour-thru electrical conductivity (EC) values of 4.0 (control), 7.0, 9.8, 12.1, or 14.2 dS·m−1, respectively. Pansy (Viola tricolor) and zinnia (Zinnia angustifolia), the most sensitive species examined, exhibited 100% mortality when exposed to an EC of 14.2 dS·m−1. The least affected species for dry weight (DW) was snapdragon (Antirrhinum majus) with a 54% reduction as EC increased from 4.0 to 14.2 dS·m−1. Only fuchsia (Fuchsia hybrida) and snapdragon were unaffected by an EC of 7.0 dS·m−1, whereas at 9.8 dS·m−1 all of the species had a significantly reduced DW as compared with control plants. Verbena (Verbena ×hybrida), petunia (Petunia ×hybrida), coleus (Solenostemon scutellarioides), and begonia (Begonia hiemalis) were the only species that did not undergo a significant height reduction in comparing 9.8 dS·m−1 to control. A classification of the 14 species is created here on the basis of plant DW to provide guidance as to which species could be irrigated with more saline water while not compromising plant growth and quality.