Evaluation of Pearl Millet Grain Hybrids for Resistance to Meloidogyne spp. and Leaf Blight Caused by Pyricularia grisea

Pearl millet, Pennisetum glaucum, has potential as a grain crop in the southeastern United States. Although it is used as a food grain in India and Africa, its primary use in the United States is high quality feed for poultry and livestock (1,6,15). Hybrids adapted to the southeast should be high yielding, resistant to the rust fungus Puccinia substriata var. indica, and early maturing. The two latter characteristics allow growers greater flexibility in planting date (May to July). In addition, pearl millet tolerates drought and low fertility conditions, thus requiring few irrigation and fertilizer inputs and is resistant to preharvest aflatoxin contamination (13,14,17). To be compatible in rotation with other crops grown in the southeast, pearl millet hybrids should not increase soilborne pathogens of plants including nematodes. Root-knot nematodes, Meloidogyne spp., are major pests of cotton, peanut, and vegetable crops in this region because of the long growing season and sandy soils. Corn (Zea mays) is commonly grown in rotation with cotton (Gossypium hirsutum) and peanut (Arachis hypogaea); however, corn is not a compatible rotation crop for cotton in fields infested with Meloidogyne incognita because it is a good host for reproduction of this nematode (4,19). Pearl millet hybrids vary in susceptibility to Meloidogyne spp. For example, ‘Gahi 1’ supported reproduction of M. incognita and M. javanica, but not M. arenaria; whereas, ‘Gahi 3’ was resistant to reproduction of all three species (9). In a field study, numbers of M. incognita increased over the growing season in soil planted to the hybrid HGM-100, but did not reduce yields suggesting some level of tolerance to nematode damage in this hybrid (10). The primary objectives of this study were to determine the resistance and/or tolerance of experimental pearl millet hybrids to M. incognita race 3 and M. arenaria race 1, and to compare the suitability of pearl millet as a host relative to corn. Resistance describes the effect of the plant on nematode reproduction, while tolerance describes the amount of host injury or yield loss from nematode infection (2). A secondary objective was to determine the severity of leaf blight, which is caused by a complex of fungal pathogens (18), because little is known about the effect of this disease on grain yield of pearl millet in the southeastern United States. In this region, Pyricularia grisea is the primary pathogen causing leaf blight on pearl millet (18). The hybrid HGM-100 is resistant to P. grisea (5); however, the reaction of the experimental hybrids is unknown. A preliminary report on this research was previously published (11).