Response of green manure species and millet cultivars to different populations of Meloidogyne java']javanica

The use of non-host cover crops is a key strategy for controlling root-knot nematodes in infested fields. However, pathogenicity of nematodes to cover crops may vary between populations and localities. This study assessed the response of green manure species and millet (Pennisetum glaucum (L.) R.Br.) cultivars to four populations of Meloidogyne javanica (denominated Mj-2, Mj-3, Mj-6 and Mj-7). Seedlings of radish (Raphanus sativus L.), pigeon pea (Cajanus cajan (L.) Huth) 'IAPAR 43', buckwheat (Fagopyrum esculentum Moench) 'IPR 92-Altar' and millet 'BRS 1501', 'ADR 300' and 'ADR 500' were inoculated with 1000 eggs and second-stage juveniles of M. javanica. Soybean (Glycine max (L.) Merr.) 'M6210 IPRO' was used as control. At 60 d after inoculation, plants were evaluated for root fresh weight, gall index (GI), number of nematodes per gram of root and reproduction factor (RF). For GI, Mj-3 and Mj-6 were the most aggressive to soybean (GI = 5.0). In pigeon pea, Mj-7 resulted in the highest GI (3.5). Radish had the lowest GI (0.67) with Mj-2. For buckwheat, Mj-3 was the most aggressive population, with a GI of 4.50. Mj-3 and Mj-7 resulted in the highest GI in 'ADR 300', and Mj-6 and Mj-7 in 'ADR 500'. The reproductive ability of nematode populations differed between hosts. Mj-2 was the most pathogenic to 'ADR 300' (RF = 10.88), Mj-3 to buckwheat (RF = 53.46) and radish (RF = 4.81), Mj-6 to 'ADR 500' (RF = 19.58) and Mj-7 to pigeon pea (RF = 2.99) and 'BRS 1501' (RF = 15.05). Soybean was susceptible to all M. javanica populations (RF = 33.69 to 257.22). Green manure species and millet cultivars varied in their responses to M. javanica populations of different origins.