was not significantly different. Percentage of effective florets was
only affected when water stressing was imposed at first bolting
stage, and was significantly decreased when compared with other
treatments except stressing at seed formation stage, which was
also lower but of non-significant level. Umbel diameter of plants
stressed at the time of first bolting was significantly smaller than
those non-stressed, stressed at seed formation and stressed at seed
maturation stages, respectively. Difference from stressing at anthe-
sis was not significant when compared to stressing at first bolting
appearance. However, water stress at the time of anthesis signif-
icantly decreased the diameter of seed head when compared to