Manipulation in canopy structure using plant growth retardant in cosmos (Cosmos sulphureus)

Abstract

An experiment titled Manipulation in Canopy Structure using Plant Growth Retardant in Cosmos (Cosmos sulphureus) was carried out to study the effect of different growth retardants on cosmos plant at the Horticultural Research cum Instructional Farm, College of Agriculture, Indira Gandhi Krishi Vishwavidyalaya, Raipur (C.G) during the year 2024-2025. The study confirmed that cosmos plants treated with foliar application of Ethephon at 900 ppm (T8) significantly reduced plant height 70.47 cm at 60 DAT and 104.65 cm at 90 DAT, increased stem diameter 15.98 mm at 60 DAT and 18.62 mm at 90 DAT and increased flower diameter (4.96 mm) comparing with all other treatments whereas, Paclobutrazol soil drenching at 5 ppm (T1) recorded highest number of primary branches per plant at both 60 DAT (16.60 branches) and 90 DAT (23.71 branches), maximum number of secondary branches per plant (23.46 branches) at 60 DAT and (80.20 branches) at 90 DAT, maximum plant spread (E-W) 74.89 cm and (N-S) 71.48 cm, Maximum number of flowers per plant 5.5 flowers at 60 DAT and 84.3 flowers at 90 DAT and days taken to 50% flowering (62.7 days) and full flowering (74.3 days) was recorded early.