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Abstract
Research was conducted to evaluate the effects of abscisic acid (ABA) and the synthetic ABA analog 8 acetylene methyl-ester abscisic acid (PBI 429) on evapotranspiration, stomatal conductance, net photosynthesis, leaf chlorophyll content, and shelf life of pansies (Viola wittrockiana). The first study was conducted using load cells to determine evapotranspirational water loss, and showed that ABA and PBI 429 both reduce evapotranspiration in a rate-dependent manner, and extend shelf life. The second study compared the long term effects of these compounds on stomatal conductance, net photosynthesis, and leaf chlorophyll. Both compounds reduced stomatal conductance and net photosynthesis in a rate-dependent manner. ABA had a greater efficacy and longevity than PBI 429 but also caused rate-dependent chlorosis. PBI 429 did not induce chlorosis, and therefore shows promise as a holding agent.