Phomopsis seed decay in soybean is one of the major diseases in soybean cultivation and harvest. Especially, hot andhumid weather in maturing season attribute to the severe loss for soybean seeds by symptom of Phomopsis. To improve thisweakness, seeds of landrace ‘KAS 360-22’ with susceptibility for Phomopsis were irradiated using a 250 Gy gamma ray in 1998.This cultivar has a few distinguishable characteristics such as resistance to Phomopsis seed decay, seed color change and highyielding, compared to landrace ‘KAS360-22’. Although the maturation period of ‘Wonyul’ (127.5 DAS (days after sowing)) is18.9 days later than that of landrace ‘KAS 360-22’ (108.6 DAS), their total yield (233.3 kg/10a) is about 11 times higher thanthat of landrace ‘KAS360-22’ (24.9 kg/10a). Their agronomic trait including resistance to Phomopsis seed decay is much betterthan standard cultivar ‘Ilpumgeomjeong’ for mixed cooking with rice.
