Reaction of soybean cultivars to Phomopsis seed decay in the Mississippi Delta, 2007.

摘要

Phomopsis seed decay (PSD) can severely affect soybean seed quality and is a problem for many soybean farmers in the southern USA. There are few management strategies for this disease, and these strategies have not completely protectedsoybean against PSD. Resistant varieties can provide some protection at no additional cost to the grower above the price of the planting seed. Soybean lines may vary for resistance or tolerance to PSD. On May 4, 2007, 50 soybean cultivars wereplanted at Stoneville, Mississippi to determine their reaction to PSD. Two lines, SS93-6012 and SS93-6181, previously reported to be PSD resistant in Missouri were included, and cultivars, Hill and Williams 82, were used as susceptible checks.Seed, 9 seed/ft of row, were planted in 9 ft long rows with 24-in. row spacing. The experimental design was a randomized complete block with four replications. Prior to planting, 30 seeds of each line were assayed for incidence of Phomopsislongicolla and germination rate. Plants were inoculated at the R5 stage with a spore suspension (10-4/ml) prepared from a combination of 10 isolates of P. longicolla cultured on acidified potato dextrose agar. All isolates were from field-grownseeds collected near Stoneville, Mississippi during 2002 to 2005. Inoculation was performed using a battery-operated backpack sprayer (30 psi) with a hand held boom containing single nozzle with an adjustable orifice. Seeds arbitrarilyselected from each replication of each line were collected when the plants were mature. A total of 100 seeds of each line were assayed for the percentage of P. longicolla infection and germination rate. Seed protein and oil concentrations from each linewere analyzed.