Evening star., 1941-03-03
Of Stars, Men
And Atoms
Notebook of Science Progress
In Laboratory, Field
And Study
BIZ Thomas r. Henry.

By 1HOHLuS II. hS7Uy.
New crop plants of vast economic i'm
portance to the American farmer may
be just over the horizon.
They are predicted by special COM
mittee of the Department of Agriculture,
appointed by former Secretary Henry
A. Wallace to forecast the future of
farming for the next decade. The most
significant results may be expected from
the use OF colchicine by plant breeders.
This is a powerful drug which is OBJ
tanned from the seeds of meadow SAT-
from, wild plant found in Asia and
Europe. 1t was once used as gout
remedy. 1t causes rapid cell develop
ment in young plants.
The prospects for cotton are especially
good, the committee reports. Several
species have desirable qualities that
could be blended into superior strain
were it not that these species are diff
cult to cross and such crosses as have
been made usually have been sterile
hybrids.
"Colchicine," the committee reports,
may give them power to reproduce so
that desirable features of several-like
resistance to drought, insects and dis
ease-might be combined in a true
breeding hybrid. The first generation
cross, for example, of Upland and Sea
Island cotton has vigor of growth, the
long staple of Sea Island and some of
the early maturity of Upland. But the
hybrid disintegrates after the first gen.
Grafton and loses its desirable qualities.
"a true breeding strain depends upon
freak of nature, twin embryo found
commonly in Sea Island and occasionally
In Upland. Usually one of the embryos
produces a shoot with only half the
number of chromosomes in one set, in
stead Of the two sets required for fer
tility. BY doubling with colchicine the
chromosome numbers of this shoot, sci
entists hope to get pure-l1ne cotton
which should breed true.
"The same is true of tobacco. Guilt
vated tobacco crossed with wild types
produces infertile hybrids. BY doubling
the number of chromosomes, fertile and
approximately true-breeding hybrids
have been obtained of possible economic
value"
The Department of Agriculture plant
breeders, the committee reports, are
working to produce fertile hybrids from
such crosses as the loganberry and ordi-
nary blackberry. The hybrids produce
fruit of exceptional flavor, but the plants
thus far produced have been incapable
of reproduction. BY crossing the red
raspberry with other berries better able
to withstand heat it may be possible to
produce a new variety which will grow
much farther South. Horticulturists
already have doubled the number of
chromosomes in strawberries and
peaches, but the effect can be deter
mined only when the fruit is produced.
For the peach this will be two or three
years hence.
"Colchicine," reports the committee,
affects the cell. the unit of life which
begins with a single fertilized cell and
divides into two, four, eight. ETC., into
countless millions AS the cells divide,
each has sets of chromosomes contain
ing genes which determine the behavior
of the plant. These heritable factors
have been the basis of modern plant
breeding.
"The chromosome number remains
constant as the cells divide, if the plant
grows naturally. Each cell has the same
factors that influence characteristics
like color, disease resistance, height and
yield. Nature prevents a piling up of
chromosomes In plants and animals by
halving the number of reproductive cells.
Fertilization of egg cells restores the
normal number of chromosomes found
in the body cells Thus the appearance
and behavior of the plant is inherited
through genes obtained from both par
ents. Although the plant body dies, the
germ plasm lives on in the seeds. Sc
lecting plants with superior germ plasm
is the basis of selective breeding.
Fertile hybrids are obtained only
when the parent chromosomes pair sue
cessfully. Lack of perfect pairing leads
to an unequal distribution of chromo-
somes to the new cells with the result
that they fail to function. For this rea-
son offspring from crosses where the
parent chromosomes are unequal in
number or have some other fundamental
difference have been difficult, if not i'm
possible. to obtain"
Colchicine also, it is explained, may
eventually make possible the production
of new varieties of animals, but no sue
cessful experiments have been carried
out this far in the field
Essentially the effects of colchicine
are to speed up greatly the progress Of
controlled evolution. Man has for the
first time means of producing new
forms of life, more suited to his needs.
With the progress up to date in plant
breeding the committee reports, new
kinds of crops are being announced al
most daily and a great acceleration can