EFFECT OF GROWTH RETARDANTS ON GROWTH AND ALCALOID FORMATION IN DATURA METEL VAR. FASTUOSA

Abstract

Growth retardants CCC and B–nine were applied to young plants of Datura metel var. fastuosa in the form of spray at weekly intervals for about 6 weeks, using a wide range of concentrations of these chemicals from 1000 ppm with increases– to 20–40 fold. Of the two chemicals tried B–Nine proved more effective in arresting stem and petiole growth. No phytotoxicity was noted with it, whereas high concentrations of CCC like 30000 ppm were toxic and caused chlorosis even with concentration of 20000 ppm. A decrease of 44 % and 40 % over control in stem height was observed with 40000 and 20000 ppm B–nine, resulting in a decrease of 40.7 and 26.6 % respectively over control in total dry weights of the treated plants. The inhibitory effects on height and growth were greater in plants receiving higher doses of B–nine than those receiving lower concentrations. Alkaloid concentration in the leaves increased as a result of these treatments. An increase of 60 % over control in total alkaloids of leaves was found with 20 000 ppm B–nine and another increase of 49 % was noted with 20 000 ppm CÇC. Increases with rest of the concentrations were insignificant. It appears that generally, higher concentrations of these chemicals were more conducive to increased alkaloid production but further high doses would become necessary for growth retardation.

CCC did not induce significant reductions in height and consequently in the total dry weights of the experimental plants, on the other hand these plants were slightly taller than the controls. Number of leaves and number of nodes per plant were same in treated as well as untreated groups, but node to node distances were reduced in treated plants. Flowering was also delayed as a result of these treatments. Some of these effects suggest that the mode of action of these chemicals is antigibberellin like in nature. However, the morphological and alkaloidal responses evoked as a result of treatments with growth retardants are of fundamental and practical value, that may be profitably utilized for large scale cultivation of this drug plant for its alkaloids.