Application of Benzyladenine and Gibberellic Acid Prevents Abscisic Acid Induced Leaf Chlorosis In Pansy and Viola

Maintaining the postproduction quality of floriculture crops is a major economic issue for the green industry.  Profit losses can result from harsh environmental conditions that are encountered by finished floriculture crops in the retail setting or during shipping.  Such conditions include extreme heat and drought stress.  For floriculture crops to tolerate environmental stresses, such as drought, they must reduce water loss.  The plant hormone abscisic acid (ABA) has been associated with many physiological responses in plants, among which is the closing of the stomata to reduce water loss during drought stress.  Applications of s-ABA, an ABA biochemical (Valent Biosciences Corp.), were effective at reducing water loss but resulted in leaf chlorosis in some plant species such as Viola x wittrockiana (pansy) and Viola cornuta (viola).  This leaf chlorosis resulted in an unmarketable crop regardless of the developmental stage of the pansies or violas.  To reduce or eliminate the leaf chlorosis, applications of benzyladenine (BA), gibberellic acid (GA₄₊₇), a combination of benzyladenine and gibberellic acid (BA and GA₄₊₇) and ethylene receptor blocker (1-MCP) were evaluated.  Applications of 5 and 10 mg·L^-1 benzyladenine and gibberellic acid (BA and GA₄₊₇) prior to an application of 250 or 500 mg·L^-1 s-ABA eliminated leaf chlorosis and maintained the water status of the plant allowing marketability of the crops to be maintained even under severe drought conditions.