Varietal response to downy mildew disease in pearl millet (Pennisetum glaucum L.R. Br.)

摘要

In Pearl millet, downy mildew is one of the most important disease causing serious problem in Tamil Nadu. The development of hybrids with resistance to downy mildew disease will provide the best means of control and is an important objective in pearl millet improvement. Hence, an attempt was made to screen the pearl millet genotypes with resistance to downy mildew disease at Millet Breeding Station, Tamil Nadu Agricultural University, Coimbatore during Kharif 1998-99. Eight male sterile lines fromdiverse cytoplasmic sources were crossed with twelve restorer lines which are resistant to downy mildew disease during Kharif 1997 - 98 at Millet Breeding Station, TNAU, Coimbatore. The resultant 96 hybrids with their parents and the national susceptiblecheck NHB3 were raised in hot spot areas during September- October. The infector row technique at sick plot location was followed (Williams et al. 1981). Eight test rows of 3m long were sown between two infector rows of highly susceptible pearl millet hybrid NHB3 which was sown 25 days earlier. The seeds of NBB3 was also planted all around the field to get maximum intensity of disease incidence to test entries. The number of plants in each genotype was maintained as twenty. The infector row was inoculated by placing infected plant debris containing sporangia in the whorls of 30 - 40 days old plant. At soft dough stage, disease sevearity was recorded and expressed as percentage of infected plants. The range of 1-5 percent, 6 - 20 percent, 26 - 40 percent and above 40 percent were considered as resistant, moderately resistant, tolerant and susceptible respectively. Below 1 percent of disease incidence was considered as completely resistant.