GERMINATION AND GROWTH RESPONSE OF PARTHENIUM HYSTEROPHORUS TO LEAD TOXICITY

Abstract

Parthenium (Parthenium hysterophorus L.), a Mexican weed, entered in Pakistan during early 90s and now has established itself in various parts of the country due to its fast growth rate, high seed production potential, allelopathic nature, non-palatability and absence of natural enemies. The weed is considered highly competitive and tolerant to various stresses. This study was carried out to assess its tolerance to lead (Pb) toxicity in vitro. Seven concentrations of Pb ⁽II) (20, 40, 60, …, 140 ppm) in the form of lead (II) nitrate were prepared and their effect was investigated on germination and growth of parthenium. The experiment was carried out in a completely randomized design with four replications. Different concentrations of Pb (II) reduced germination by 7–82%, shoot length by 4–86%, root length by 14–92%, fresh biomass by 27–95% and dry biomass by 33–98% over control. This study concludes that germination and growth of parthenium is very sensitive to 100 ppm concentration of Pb (II) while a concentration of 140 ppm is highly detrimental to parthenium causing up to 82% reduction in its germination.