The Effect of Pot Size and Abscisic Acid Rate On Time to Leaf Wilt for Flowering New Guinea Impatiens

Recently, abscisic acid (ABA) spray treatments up to 100 mg L^-1 were found to delay leaf wilting of New Guinea Impatiens that can occur due to water deficit stress during postharvest handling.  However, this effect was not uniform across the cultivars studied.  In the present study, we evaluated the effect of rates up to 2000 mg L^-1 and pot size on the time from application to leaf wilt for New Guinea Impatiens.  In the first experiment, plants of two cultivars at commercial maturity in 15 cm pots were sprayed to runoff with 0, 100, 500, 1000, and 2000 mg L^-1 ABA.  In a second experiment, plants of one cultivar were grown in either 10 or 15 cm pots and sprayed as in the first experiment.  Plants in both size pots were potted at the same time and reached commercial maturity at the same time.  The plants in the 10 cm pots were observed to be in a more root bound condition than the plants in the 15 cm pots at the time of application.  All plants from both experiments were watered thoroughly just prior to application.  After the spray applications, the foliage was allowed to dry.  The plants were then held at 20°C for evaluation of treatment responses.  For the first experiment, the time to wilt increased significantly with rate regardless of cultivar up to 500 mg L^-1.  This treatment doubled the time to wilt when comparing it to the control.  There was very little additional benefit for rates higher than 500 mg L^-1.  For the second experiment, plants in 10 cm pots wilted 3.5 days earlier than plants in the 15 cm pots.  The response to ABA rate was similar to the first experiment.  Plants grown in smaller pots or in a root bound condition may require higher rates of ABA to produce the same delay in wilting seen for plants in larger pots.

The authors would like to acknowledge funding from Valent BioSciences and plants from Ball Horticultural Company.