Effects of some common weeds from Pakistan on plant-parasitic nematodes in vitro and population densities and survival of Meloidogyne incognita in okra and brinjal

Abstract

Aqueous extracts of the four weed species Conyza canadensis, Blumea obliqua, Amaranthus viridis and Eclipta prostrata caused substantial mortality of the plant-parasitic nematodes Xiphinema americanum, Tylenchulus semipenetrans and Meloidogyne incognita in vitro. Conyza canadensis and A. viridis were the most effective in killing the nematodes while E. prostrata was the least effective. Soil amendment with C. canadensis or A. viridis at the highest concentration (5 %) resulted in a significant reduction in soil population densities, root-knot development, and nematode reproductive potential of M. incognita in okra and brinjal. Soil amendment with B. obliqua at 5% concentration increased plant height of both crops while A. viridis at 5% concentration reduced the fresh weight of okra shoots. Ether extracts of the weed species revealed qualitative differences in phenolic compounds. Altogether, thirteen phenolic compounds were isolated from the weeds with A. viridis yielding the highest number (6) of such compounds.