Flooding is one of the factors that causes serious damage to agricultural production, in paddy rice areas. In
the Mekong river delta of Viet Nam, intensive rice production systems consist of 2 to 3 consecutive crops per year
with short intervals between each crop. This causes straws and stubbles to remain un-decomposed under field
water, potentially change physical, chemical and biological characteristics of soil that affect rice growth and yield.
The study investigated the effects of straw and stubble incorporation equivalent to 5 tons per ha under artificia l
flooding on growth and yield of IR64 -Sub1 rice variety grown in pots. IR64-Sub1 seedlings’ survival decreased
consequently with prolonged submergence, around 10% after being flooded continuously for 20 days.
Organic residual incorporation under 60 cm depth of water continuously in 15 days at 3-day-seedlings altered pH,
EC, and dissolved oxygen of the water and affetced first internode elongation and delayed harvest time up to 20
days in comparison to that of the control. The incorporation of burnt straws and stubbles had a tendency to
improve rice yield regardless to submergence but flooded condition reduced seed discoloration and en hanced
spikelet filling significantly.