Life cycle of the rice root-knot nematode<i>Meloidogyne graminicola</i>at different temperatures under non-flooded and flooded conditions

Abstract

The life cycle of the rice root-knot nematode, Meloidogyne graminicola, was studied in an indoor growth chamber on the susceptible Asian rice cultivar UPLRi-5 at 29/26 and 36/32 °C (day/night temperature) under non-flooded and flooded conditions. Adult females were observed 11 days after inoculation (DAI) at 36/32 °C under non-flooded conditions and at 29/26 °C under flooded conditions. At 29/26 °C under non-flooded conditions, adult females were observed at 13 DAI. Completion of the life cycle from the second-stage juvenile (J2) to the second-generation J2 at 29/26 °C under non-flooded conditions was 20 days, and 19 days at 29/26 and 36/32 °C under flooded and non-flooded conditions, respectively. At 36/32 °C under non-flooded conditions, about one-third more adult females were observed compared with the other treatments but this did not result in more second-generation J2. The number of second-generation J2 was significantly higher (more than 15 times) at 29/26 °C under flooded conditions compared with the other treatments. At 25 DAI (i.e. after the second-generation J2 had been generated), a significant 3.5 fold increase in the number of galls per root system was observed on the plants grown at 29/26 °C under non-flooded conditions compared with the other treatments.