Study of PEG-6000 effect on growth and physiological parameters of China aster (Callistephus chinensis) and strawflower (Helichrysum bracteatum) in in vivo conditions

Abstract

Drought stress is one of the most important environmental factors in reduction of growth, development and production of plants. In our study, in order to simulate water deficit induced by osmotic stress, different concentrations of polyethylene glycol (PEG) 6000 were used: 10 %, 20 % and 40 %. The goal of the investigation is to establish the growth and physiological response of annual flowers (Callistephus chinensis L. and Helichrysum bracteatum) to drought. Seedlings from Callistephus chinensis L. and Helichrysum bracteatum react individually on the simulated drought stress, using PEG in controlled (in vivo) conditions-the detected water deficit varies between 49.9 % to 63.12 %-at 40 % PEG. Changes were identified in the seedling growth, cell membrane stability and the RWC in plant tissues, corresponding to the stress duration and increase of the PEG concentration. The usage of 40 % for 6 days was the maximum admissible for the seedlings from Callistephus chinensis L. and Helichrysum bracteatum, based on the low percentage of plants which regained their development.