Govind Ballabh Pant University of Agriculture & Technology, Pantnagar, U.S. Nagar, Uttaranchal - 263145
*Present address: Division of Fruits and Horticultural Technology, I.A.R.I., New Delhi - 110012, E-mail: mns_fht@rediffmail.com
Present investigation was carried out to analyse the response of varying concentrations of paclobutrazol in plant tissues. Evidences were produced by examining the interaction of gibberellic acid (GA3) and paclobutrazol (PBZ) in lettuce hypocotyl bioassay and 6-benzyl aminopurine (BAP) and paclobutrazol in radish cotyledon enlargement test that paclobutrazol counteracts gibberellin activity when applied exogenously. It also favoured radish cotyledon enlargement at low concentration without counteracting BAP action. Paclobutrazol slightly increased radish cotyledon growth at low concentration (up to 0.01 ppm) and could not counteract the growth caused by 1.0 ppm BAP at its 0.001 to 1.0 ppm concentrations suggesting independent effect of paclobutrazol to that of BAP. Furthermore, the activity of paclobutrazol was tested in corn root curvature test and it was found that PBZ concentrations from 0.001 to 10.0 ppm linearly increased the percentage of corn roots showing more than 90° curvature.
Paclobutrazol, cultar, lettuce hypocotyle growth test, radish cotyledon enlargement test, corn root curvature test
