Endogenous levels of ABA in zygotic embryos
differed considerably depending upon the sampling
date (Fig. 3). The concentration of ABA in
diploid ZE increased following pollination with a
peak at 24 DAP (51.1 mg g1 FW) and then
decreased being lowest at 56 DAP (1.5 mg g1
FW). No data are available for embryos at earlier
developmental stages. However, based on data
obtained for whole ovules isolated 14 DAP it
could be assumed that in the earlier stages the
amount of ABA in embryos was very low since the
whole ovule contained only 0.014 mg of ABA
(Table 1). Essential changes in the concentration
of ABA were noted between 21 and 28 DAP when
it first increased by nearly double (between 21 and
24 DAP) and then decreased more than 3-fold
(within the following 4 days). The maximum appeared
when the embryo was morphologically
completed (torpedo stage), which in the case of
this cucumber line is between 18 and 24 DAP as
shown by Tarkowska et al. [20]. The maximum
and minimum values differed approximately 35-
fold. During seed development and maturation a
further reduction in concentration was recorded
(Fig. 3).