Abstract
The effects of the flooding treatment given at various stages after sowing on the seeding emergence and growth of ten common buckwheat varieties or lines were examined. Flooding treatment given three days after sowing reduced emergence rate more severely than that given on the day of sowing. In addition, the emergence rate decreased as the day of flooding treatment was delayed from 0 to 3 days. The present results showed that the effect of flooding treatment varied with the root length at the time of the flooding treatment. The plant height, seed number and dry weight were severely reduced by the flooding treatment given during the early growth stage, and not by the treatment after the flowering stage. Flooding treatment at the seeding stage decreased not only seeding emergence but also growth of the plants. Thus the seeding stage was most vulnerable to wet injury in common buckwheat. The relationship between root length at the start of flooding treatment and the seeding emergence rate was examined at 15°C, 20°C, and 25°C. The emergence rate was decreased by the treatment given when the root length was 30-70 mm independently of temperature, and even when the root length was 3 mm at the 15 and 20°C. For breeding of wet injury-tolerant buckwheat, selection of the lines tolerant to flooding treatment given at the stage with 3-70 mm roots may be effective.
