Background and Purpose: Cytokinins are a group of plant hormones that have an important role in plant growth and developmental processes. Chlorophyll content is an extremely important parameter in estimating the plant production level. Since bryophytes do not have such economical importance as vascular plants and their production in many ecosystems is small, they remain uninteresting for studying their chlorophyll level. The aim of this study was to compare the effect of different cytokinins on chlorophyll retention in moss B. argeteum gametophyte shoots grown in natural conditions with those grown in in vitro culture

Material and Methods: The effect of different cytokinins: kinetin (KIN), 6-benzylaminopurine (BAP) and thidiazuron (TDZ) on chlorophyll retention of the moss Bryum argenteum Hedw. (Bryaceae) derived from in vitro culture or grown in nature was tested. Plants derived from in vitro culture were grown on Murashige and Skoog (MS) medium at 25±2°C. Gametophyte shoots were used in experiments where influence of different concentrations (0.001–10 mM) of three cytokinins was used to investigate their effect on chlorophyll-a, -b and total chlorophyll retention

Results and Conclusions: Cytokinins had a positive but unequal influence on chlorophyll retention in both plant groups – plants derived from in vitro culture and plants grown in the nature. Kinetin proved to be the most effective cytokinin in chlorophyll retention. Exogenous application of kinetin increased chlorophyll content with concentration (0–10mM). BAP had similar trends in in vitro and native mosses, increasing chlorophyll content up to 1 mMand then significantly decreasing, although the chlorophyll content was greater in in vitro grown plants. TDZ showed significantly better effect in in vitro cultured moss shoots, but when applied in concentrations higher than 0.1 mM, total chlorophyll content decreased