Evaluation location: Illinois, United States
Seeds were placed on moist filter paper in Petri plates and germinated. If available, five seedlings of each accession were transplanted into 7- cm diameter clay pots containing 180 cm3 of sand and placed on a greenhouse bench. Depending on the accession, plants were grown for 3-12 months. Supplemental HID lighting was provided to maintain a 14-hour day length. One week before inoculation, seedlings of H. glycines-susceptible cv. Lee 74 soybean were transplanted into pots as described above. Plants were inoculated with 3,000 eggs and J2 obtained from females and cysts of Hg Type 0 raised on Lee 74 soybean (Assuncao et al., 2004) and maintained on a greenhouse bench for approximately 1 month. Supplemental heating and cooling were provided to maintain soil temperatures of 24-30?C. When mature females appeared on roots of Lee 74 soybean (1 month), the root system of each plant was dipped vigorously several times in a beaker containing 3 L of water to remove soil and females from the roots. Roots were placed on nested 850- and 250-um-pore sieves and sprayed with a strong stream of water to remove adhering females. The soil was suspended in the water and gravity sieving using the nested sieves was used to extract females from the soil suspension (Cobb, 1918). Females were collected from the 250-um-pore sieve and counted with the aid of a dissecting microscope. The thoroughly cleaned roots were placed in a drying oven at 70C for 48 hours. Roots were removed, allowed to equilibrate for 24 hours at room temperature and humidity, and weighed. A female index (FI) ((no. females per 0.1 g dry root of accession/no. females per 0.1 g dry root of Lee 74) x100) was calculated for each accession and a rating of resistance classified as: resistant (R): 0