2.4. Field preparation
The fields were ploughed 15–20 cm deep using a tractor-drawn rotary tiller. Following general local recommendations, a basal fertilizer, at the rate of 30 kg N ha−1, 45 kg P2O5 ha−1 and 30 kg K2O ha−1, was incorporated into the 15-cm soil layer by puddling with a light rotary tiller. After land preparations, the plots for the flood treatments were submerged and seedlings were transplanted into the plots. No top dressing was applied during the flooding treatment.