Influence of Different Herbicides on Weed Dynamics, Growth and Yield of Chrysanthemum (Dendranthema grandiflora T.)

A field experiment was conducted at Floricultural Research Station, Hyderabad, Telangana under irrigated conditions for three consecutive years from 2009−10 to 2011−12 on Chrysanthemum variety Mayuri with pre-emergence herbicides Butachlor, Pendimethalin, Fluchloralin and Diuron in different concentrations. The experiment was laid out in randomized block design with three replications and ten treatments in a set. The dominating weed species observed in the experimental site were Parthenium histerophorus, Amaranthus viridis, Chenopodium album, Portulaca oleracea etc. All the herbicidal treatments significantly reduced the weed density, fresh and dry weight of weeds. Statistical analysis of the experiment revealed that the application of Pendimethalin @ 0.75 kg a.i. ha⁻¹ exhibited the best performance with minimum weed density (20.72 m⁻²), weed fresh biomass (96.35 g), weed dry biomass (24.61 g) and higher weed control efficiency of 71.16% followed by Pendimethalin @ 1.0 kg a.i. ha⁻¹. In most of the treatments maximum weed count was noticed at 50 to 75 DAP. Subsequently the application of Pendimethalin @ 0.75 kg a.i. ha⁻¹ gave maximum plant height of 26.93 cm. With regards to plant spread, in both E-W and N-S directions, maximum spread and also number of branches plant⁻¹ was recorded by the application of pre-emergence herbicide pendimethalin @ 1.0 kg a.i. ha⁻¹. In respect of yield characters, Pendimethalin @ 0.75 kg a.i. ha⁻¹ showed maximum flower diameter (4.34 cm) and flower yield (154.85 flowers plant⁻¹) of chrysanthemum which was at par with the same chemical @ 1.0 kg a.i. ha⁻¹. The highest net returns and maximum benefit cost ratio of 3.45 were noted with Pendimethalin @ 0.75 kg a.i. ha⁻¹