yield per umbel and per plant in the first season (Table 5) resulted
from water stress at bolting or anthesis stages observed to be due
to reductions in the number of shoots and seed stalks per plant,
which followed by significant reduction in number and percentage
of effective florets of primary umbel, umbel diameter and number
of seeds/flower (Table 3). Similar findings were reported by Patil
et al. (1993) on seed onion and Laribi et al. (2009) on caraway who
reported that seed yield and its components (number of umbels per
plant, number of umbellets per umbel and 1000 seed weight) are
severely affected by water deficit. Further, it has been found that
drought stress negatively affects flower pollination by decreasing
the amount of viable pollen grain, increasing the unattractiveness
of flowers to pollinators, and decreasing the amount of nectar
produced by flowers. Consequently crop seed set is lowered.
Moreover, drought stress affects crop yield by reducing grain yield
and all yield components (Alqudah et al., 2011). In the second