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Table 1 shows the results of the sensitivity analyses for simulated change inyield for the coefficient for lateral water movement and water level at transplantingand for the coefficient for lateral water movement and deep percolation rate. Thesimulation results show that the effect of a change in lateral water movement wouldbe greater with an initial water level of +50 mm than with –200 mm at Ubon 1996because lateral water movement would be greater with a longer period of standingwater and, hence, the soil is saturated with water for a longer period. When the waterlevel at transplanting was reduced to –200 mm, the period of standing water wasshorter, and this resulted in a rather small effect on grain yield with the variation inC L . At Ubon, the effect of a change in C L became smaller as the deep percolation ratedecreased from 6 to 1 mm d –1 . With 1 mm d –1 , there was almost no water stressthroughout the growth period and hence the effect of water movement was small,whereas, with 4–6 mm d –1 , there were some periods with standing water but therewere also periods of water stress (Fig. 5 for a deep percolation rate of 6 mm d –1 ). Inthis case, there was a large simulated effect of variation in lateral water movement.The results are different for Phrae 1993, where yield potential was higher andsimulated yield was more responsive to a change in initial water level and deep per-Table 1. Simulated grain yield (t ha –1 ) for KDML105 under differentdegrees of lateral movement of water and initial water level (mm) atthe time of transplanting and deep percolation rate (mm d –1 ) at Ubon(1996) and Phrae (1993).Coefficient for lateral movementWater level at of water (C L )transplanting0.5 0.75 1.0 1.25 1.50Ubon–200 1.32 1.34 1.41 1.45 1.52+50 1.56 1.72 1.84 2.12 2.26Phrae–200 0.94 1.41 2.25 2.97 3.18+50 2.08 2.89 3.26 3.49 3.69Coefficient for lateral movementDeep percolation of water (C L )rate0.5 0.75 1.0 1.25 1.50Ubon1 2.28 2.46 2.46 2.46 2.464 1.78 1.85 2.15 2.37 2.416 1.56 1.73 1.79 1.88 2.12Phrae1 2.08 2.89 3.26 3.49 3.694 0.37 0.61 0.89 1.34 1.816 0.35 0.49 0.51 0.76 0.88122 Fukai et al