Abstract. During 50 days of experiments carried out in 2004 and 2005 a response to spraying with calcium chloride (0.1%, 0.5% and 1%) and with Arbolin 38 (containing GA₃ and BA) was studied in impatiens plants subjected to 3 drought cycles at 3 SWC levels (30%, 60% and 80%). Under water stress fresh weight of the plant aboveground part decreased, and ammonium accumulation in leaves progressed. Foliar CaCl₂ and Arbolin 038 applications modified the plant response to drought, decreasing ammonium accumulation.

The response of impatiens (Impatiens walleriana Hook)
to drought and treatments aiming to alleviate its effect

Summary

Impatiens walleriana is a popular bedding plant, often used in urban green areas where it can suffer from periodical water stress, especially when planted in containers with a limited substrate volume. In 2004 and 2005 experiments were carried out to determine plants’ response to imposed soil water deficit during three 10-day cycles separated by 10 days of normal watering. Plants were grown in a greenhouse, at three soil water contents (SWC): 80% (standard conditions), 60% (mild stress) and 30% (severe stress). At the beginning of the 50 days lasting experiments plants were sprayed with water (control), with 0.1%, 0.5% or 1% CaCl₂ or with Arbolin 038 (90 cm³·dm^-3) containing BA and GA₃. At the beginning of both years experiments and at the end of each drought cycle the above- and underground plant parts were weighted and leaf ammonium contents determined. Under soil water deficit the above ground parts grew smaller while the root weight increased. Ammonium accumulation in leaves progressed during the experiment, being the largest in plants from 30% SWC. Both, calcium chloride and Arbolin 038 counteracted ammonium accumulation and decrease in plant growth what might suggest a protective role of the above compounds in case of soil water deficit. This has, however, to be checked during future studies on other bedding plants.