Nematotoxic potential of daikon, chinaberry and purslane herbal green manures against Globodera rostochiensis in vitro and microplot

The nematotoxic potential of water extracts and green manures prepared from three plant species, daikon Raphanus sativus var. longipinnatus L., purslane Portulaca oleracea L. and chinaberry Melia azedarach L., on Globodera rostochiensis was examined in vitro and in microplots. Significant alteration in J۲ (second stage juvenile) activity and their hatching from eggs was observed with different exposure times by all plant species; more than ۹۹% of the J۲s were inactivated after ۷۲h and the same degree of inhibition in hatching of the eggs occurred after exposure to the plant extracts. In microplots, the numbers of newly formed cysts and final nematode multiplication rates were reduced in unsterilized soil at ۱, ۳ and ۵% (w:w) rates of amendment with fresh plant materials, and the infestation rates of potato plants did not differ significantly from those in soil treated with metham sodium ۳۷%. The rate of emergence of J۲ from cyst inocula declined by ۳۶% in soil treated with chinaberry and purslane and by ۷۱% in soil treated with daikon. The reduced availability of J۲ in soil must be one of the reasons for decrease in nematode multiplication rates of ۶۵% and ۸۶% where soil was amended with chinaberry/purslane and daikon, respectively. In terms of plant growth improvement and nematode control, daikon amendment outperformed other treatments, including metham sodium.

Keywords:

Globodera rostochiensis , potato , decline rate , fecundity , natural nematicide