The line Penelopa rectifies the exserted stigma in hybrids involving
Rutgers, Red cherry and L. pimpinellifolium No. 108 and the line 7/3 in
all hybrids. The exserted stigma is considered rectified when the style
extends beyond the anthers by no more than 0.5 mm. The data presented in
Table 2 show also that Penelopa rectifies the exserted stigma thanks to
the manifestation of heterosis for anther length in F1 hybrids, and the
Line 7/3, thanks to the style: the d/a values for the hybrids involving
the Line 7/3 are lowest compared with those of the remaining hybrids. This
suggests that the choice of the male parent should not be based on the
absolute style-length value nor on how much is the style below the anther
cone, but one should make crosses for detecting lines or cultivars similar
to 7/3 or Penelopa and rectifying the exserted stigma.
The comparison between field and glasshouse data suggests that in most
of the parents and hybrids an increase of style exsertion is observed in
the glasshouse, except in L. hirsutum f. glabratum and some of its hybrids.
This increase varies between 0.10 and 1.10 mm and results both from
decrease of the anther length and increase of the style length, the greater
part of the difference being attributed in many cases to the anthers.
Generally, the anthers show a clear tendency toward shortening under
unfavourable conditions, which is absent only in hirsutum f. glabratum and
Penelopa, the latter being the result of remote hybridization between L.
esculentum and S. Pennellii.
No regularity in lengthening of the style under unfavourable con-
ditions was revealed; lengthening was observed in several cases, but many
cases with practically unchanged style length were also observed.
Investigations on the influence of
irradiation of pollen with gamma rays
are being made in several directions:
establishing the percentage of
germination of pollen on the 3rd hour
after placing it in nutrient medium,
cytological studies on
Daskaloff, Chr., M. Konstantinova and
I. Georgieva Influence of pollen
with gamma rays upon germination
percentage of fruit setting and
crossability in tomato.
germination of irradiated pollen upon the stigma, the influence of irradiated
pollen on the percentage of fruit setting and fruit seeding in crossing, the
influence of irradiated pollen for improvement of crossability in interspecific
tomato crosses.
The results on the 3rd hour after placing of pollen for germination
were that the gamma irradiated pollen germinated while the control pollen
showed lower percentage of germination or no germination at all.
The cytological observations made with a fluorescent microscope
showed a clearly expressed enhancing effect of the irradiation of pollen
with gamma rays.
The percentage of crosses setting fruits at pollination with pollen
treated with gamma rays in all crosses was higher than controls. The
difference between the two variants had significance of first range.
Substantial differences were not noted on the seeding and 1000 seed weight
(Table 1).
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