Under field conditions, particularly in
summer or in tropical areas with low
humidity, as in Trujillo, Peru,
Perez Lopez, F. A method of field
hybridization. [Submitted by
A. von der Pahlen]
the hot dry conditions induce the failure of many crosses on flowers that
are enclosed in bags. Since 1965 we have eliminated the need for covering
flowers, using instead the anther cone of the male according to the
following method:
For the female parent:
a) Select buds in which the corolla has not yet unfurled. Buds
with corolla tips on the verge of separating at the tip are
ideal.
b) Separate the corolla segments so that they lie with the calyx. c)
Cut each stamen longitudinally along its margin with the others
and remove with forceps.
For the male parent:
d) Select flowers that are completely open.
e) Cut the base of the anther cone with nails of the thumb and index
finger.
f) Remove style from the cone with forceps.
For pollination:
g) Place the cone obtained in step (e) as a cap over the pistil of
the emasculated flower. Label.
Using this system, we have made intraspecific, interspecific, and
intergeneric crosses. We made the interspecific cross L. esculentum x
L. pimpinellifolium, using the latter as male parent, and the inter-
generic cross L. esculentum x Solanum agreifolium, using the latter as
male parent. Reciprocal crosses were not successful.
The time required per pollination using this method was one minute
per cross, whereas with the use of bags it took from three to five minutes
per cross. The degree of success with this method in various tests is
presented below.
Quiros, C. F. High tolerance of
the heterochromatic 2S•2S
isochromosome.
Moens (TGC 13: 16-17, 1963;
Can. J. of Gen. Cytol. 7:296-303, 1965)
obtained the completely heterochromatic
2S•2S isochromosome as a derivative of
a primary trisomic for the second
chromosome, the nucleolar chromosome, in the tomato. 2S•2S consists of a
centromere flanked on each side by a short arm of chromosome 2, and lacks the
satellites (reduced isochromosome according to Moens) but has the nucleolar
organizer regions subterminally located.
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