Production of Flooded Rice Seedling in Niigata District

Rice seeds were sown in nursery box at a density of 170g/box. The nursery boxes were then set in the greenhouse and covered with plastic film for warming and maintaining high humidity. Young rice seedlings were raised in a conventional system and a flooded nursery production system (flooded system). The plastic film was removed at the 2.5 leaf stage of rice seedling in both systems. In the conventional system, watering was performed every day until the transplanting of rice seedlings, and the side films of the greenhouse opened on fine days and closed on cloudy, rainy and windy days. In the flooded system, water was supplied into flooded pool settled nursery boxes 5 times during the seedling production and the side film opened all day long until transplanting. The soil temperature in the nursery box in flooded system was 1-6°C lower than that in the conventional system. Both seedlings grown through the conventional system and the flooded system had expanded 4.2 leaves on April 30, just before transplanting of rice. However, the seedlings grown through flooded system showed a higher plant length and had more vigorous white roots than those grown through the conventional system. The rice grain yield showed 568kg/10a in the paddy planted flooded seedlings, the same as that for the paddy planted seedlings raised in the conventional system. These results indicate that the flooded system led to reduction in watering and ventilation work.