The Washington herald. [volume] (Washington, D.C.) 1906-1939, 1921-08-31
HOW DO POTATOES GROwt
ANSWERED BY TESTS.

The raiser Of potatoes. whether he
Operates commercially on a large
area or has just a personal supply
patch in his back yard OF a city loI.
will be interested In the Information
the scientists of the Bureau Of Plant
Industry OF the Department of Agrf-
culture have obtained from a series
of experiments in potato growth. the
results Of which have just been pub
lished in a department bulletin.
Many questions have been asked
about the growth and yield Of one OF
Americas largest crops. and in the
past they have been only incom-
pletely answered. Now the potato
experts can answer these questions:
How do potatoes grow? Why DO
some vines produce many tubers ard
others only a few? Do big seed
pieces produce better potatoes than
small pieces? when does the tuber
begin TO form? When does moisture
have the most effect on the produc-
ton Of potatoes What rs the rela-
tion OF soil to potato production1
Tuber formation, the department
experts state. begins in general at
about the end of the period Of flower
bud development. although this is
not in all cases an exact criterion.
Experiments showed that the num-
Der, as well as the size. Of potatoes
in hill increased for several weeks
after the first potatoes were large
enough to dig. small increase in
the weight Of tubers was found to
occur even after the vines had been
killed by frost The maximum rate
of growth Of the tubers was found
to occur. about the last Of August or
nf kfah
proXimately so days after planting.
An interesting development Of the
| experiments was that the number
and weight Of tubers per hill were
found to be influenced by the size
and the kind Of seed planted. Whole
potatoes used as seed yielded heav>
Ter than half potatoes. and these
more than quarters, and the larger
the seed piece the greater the yield
per hill. 4 whole potato used as seed
yielded more than a half or quarter
| potato Of equal weight
The experiments showed that ap-
4 parently light soils are better for
! potatoes than heavy soils. The low
est production Of tubers. with re-
speCt to both number and weight
/ per hill, was on the heaviest soil;
( the highest numbers and yields
were produced on the nEhleSt SOIL.
The department experts deem il pos
sible. however, that these results
might be modified somewhat under
different climatic conditions
Two-year tests with irrigation in
dictate that the early application OF
water before tuber formation had
started resulted in an increase in
the number OF tubers as well as In
the weight per hill. Late irrigation
actually increased the weight but
made little difference in the number
OF tubers per hill. The irrigation
Experiments were not carried TO a
final conclusion, but indicate that
each application OF water at almost
any period in the growth OF the
plant. provided excessive quantities
are not used. may be expected TO
produce an increase in the weight
OF the crop. but that little or no in
crease in the number OF tubers IL
likely to result from irrigation after
tuber formation is we'll started.
The bulletin contains an interests
ing description OF the tuber-bearing
parts Of potatoes and their method
of growth.