3.4.2. Water depth

  3.4.2. Water depth

 

  Rice seed can germinate under anaerobic conditions.The subsequent growth however is greatly affected by oxygen supply. In deep flooded soil where oxygen is limited, germination occurs normally, but the coleoptile becomes unusually long and the first leaf, radicle, and nordal roots may not grow at all or their growth may be highly impaired. Finally deep flooding results in tall and weak seedling and poor root growth because of lack of air in the soil. Those tall and weak seedlings are easily damaged when they are transplanted. However when seedlings are raised in shallow water, they are short, strong, and good in root growth. The healthy seedlings are not easily damaged when they are transplanted in the rice field.