Paclobutrazol (PCB) and ethepon were applied as foliar sprays (25, 50, 100 ppm and 1.0 mM and 1.5 mM)
to greenhouse-grown plants of Saussurea costus (Falc.) Lipsch. seedlings. Under stress conditions the growth of the
PCB and ethepon treated seedlings was measured by leaf area, root length and root dry weight. A significant
increment in root length was recorded for all treatments and showed a concentration-dependent pattern excluding for
50 ppm PCB treatment where the results were non-significant at 5% P level. Photosynthetic rate (A), transpiration
rate (E) and stomatal conductance (gS) were found decreased in all the treatments as compared to control. A decrease
in fluorescence ratio (Fv /Fm) indicated lower photosynthetic efficiency. Based on the results of this study, we
presume that the stress caused by PCB and ethepon probably contributes to some extent to the inferior gas exchange
but an increase in root length. PCB had a more inhibitory effect than ethepon. [Nature and Science. 2009;
7(8):53-62]. (ISSN: 1545-0740).