Host status of plant species with nematicidal activity against meloidogyne graminicola (Golden & Birchfield)

Abstract

The rice root-knot nematode, Meloidogyne graminicola (Golden & Birchfield), is a nematode first described in 1965 from grasses and oats in Louisiana (US), and currently spread in rice crops in Asia, parts of the Americas and Africa. It can be detected in a wide range of more than 98 host plant species. In 2016 M. graminicola was detected for the first time in some rice fields of Northern Italy. In this paper, two greenhouse experiments (the first at 21-22 °C and the second one at 26-28 °C) are reported and discussed, in which three species containing bioactive compounds, Lepidium campestre (L.) R. Br., Eruca sativa Mill. cv. Nemat, and Crotalaria juncea L., were compared with Cucumis sativus L., a good host of M. graminicola, as control. Seedlings of each plant species were transplanted in pots containing mean 50 J2s 100 cm−3 soil. Three assessments were carried out about 30, 60, 90 days after transplantation, on both soil and roots. Temperature influenced M. graminicola life cycle, which was never completed at 21-22 °C; conversely, at 26-28 °C, both E. sativa and C. juncea reached a reproduction rate (R) = 0.01, confirming to be poor hosts, effective in decreasing the nematode infestation on the roots and in the soil, while L. campestre (R = 4.01) demonstrated to be a good host of M. graminicola more than the control C. sativus (R = 2.12), increasing considerably the nematode population after about 90 days.