EVALUATING THE HERBICIDAL POTENTIAL OF Dicliptera bupleuroides AND Justicia adhatoda AGAINST BROADLEAF NOXIOUS WEEDS

Weeds are one of the most important factors influencing growth yield and quality of crop produce. There are many methods to control weeds but chemical control is the most effective. However, use of herbicides results in many ecological and health related issues. The use of plant extracts in mixture with herbicides would be a good option for reducing the herbicide doses and tackling the problem of herbicide resistance. Laboratory and green house experiments were conducted at Department of Agronomy, College of Agriculture, University of Sargodha, Pakistan to evaluate the herbicidal potential of two plants of Acanthaceae family collected from Soon Valley, district Khushab against selected cropland weeds. In the first experiment, aqueous and N-hexane extracts of Dicliptera bupleuroides Nees. and Justicia adhatoda L. were evaluated for their pre-germination phytotoxic potential against the germination of lettuce (Lactuca sativa L.). In the second experiment, the extracts were further tested against the germination and seedling growth of four broadleaf weed species viz. Trianthema portulacastrum L., Parthenium hysterophorus L., Rumex dentatus and Melilotus indica through petri plate and pot bioassays. Experiments were laid out by using completely randomized design with factorial arrangement. Results indicated that D. bupleuroides aqueous extract showed highly significant suppressive effect against germination (97%), dry weight (43%), shoot (84%) and root length (88%) of lettuce. The D. bupleuroides aqueous extracts caused reduction in germination index (up to 83%), germination energy (up to 86%), germination percentage (up to 66%), shoot (up to 51%) and root length (up to 56%), of weeds. Leaf area was proved to be more susceptible towards plants aqueous extracts. It is concluded that D. bupleuroides plants has substantial phytotoxic potential against germination and seedling growth of lettuce and weeds.