Attempts to force teosinte into flower in mid-summer, in order to facilitate hybridizing it with maize, have afforded considerable information concerning the flowering time of teosinte under diverse conditions. The possibility that some of this information may be of use to others suggests its publication. The paper is, therefore, to be considered as a help in the technique of teosinte and maize hybridization rather than a contribution ~to the solution of the physiological problems involved

Emerson, R. A.

English

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Agronomy & Horticulture -- Faculty Publications Agronomy and Horticulture Department
1924
Control of Flowering in Teosinte: Short-Day
Treatment Brings Early Flowers
R. A. Emerson
University of Nebraska-Lincoln
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Emerson, R. A., "Control of Flowering in Teosinte: Short-Day Treatment Brings Early Flowers" (1924). Agronomy & Horticulture --
Faculty Publications. 918.
http://digitalcommons.unl.edu/agronomyfacpub/918
CONTROL OF FLOWERING IN TEOSINTE 
Short-Day Treatment Brings Early Flowers 
R. A. EMERSON 
Cornell University, Ithaca, N. Y. 
A TTEMPTS to force teosinte into flower in mid-summer, in order to facilitate hybridizing 
it with maize, have afforded consider-
able information concerning the flower-
ing time of teosinte under diverse con-
ditions. The possibility that some of 
this information may be of use to 
others suggests its publication. The 
paper is, therefore, to be considered 
as a help in the technique of teosinte 
and maize hvbridization rather than a 
contribution ~to the solution of the 
physiological problems involved. 
Early Observations· 
Some years ago the writer observed 
that teosinte that germinated in the 
greenhouse at Ithaca, New York, dur-
ing December came into flower within 
a few months, while plants of the same 
stock started almost any time from 
:March to June did not blossom until 
October. With the publication of the 
results of Garner and Allard with 
respect to the effects of length of day 
on the blossoming time of various 
plants, the reason for this behavior of 
teosinte became apparent. 
The first few times that the writer 
attempted to force teostinte into flower 
in time to cross it with maize grown 
out-of-doors. he began the short-day 
treatment too early or too late for best 
results. It seemed worth while, there-
fore, to determine as nearly as possible 
when the treatment should be begun, 
how long it must be continued, the 
degree of darkness of the room into 
which the plants were placed to shorten 
the time of exposure to daylight, and 
kindred matters. The time and facili-
ties ayailable did not permit as elabor-
41 
ate an experiment as desired, but the 
results, so far as they go, were fairly 
decisive, at least on certain points. -
Methods Used 
Teosinte plants of stocks originally 
obtained from Messrs. Collins and 
Kempton of the United States Depart-
ment of Agriculture, and plants of 
maize collected in Guatemala by Dr. 
Knudson of Cornell University were 
started in pots in the greenhouse on 
May 1st, 1923. Germination was fair-
ly prompt in most cases, -but no records 
of the date of germination were made. 
For perennial teosinte, offsets rather 
than seeds were used. All plants were 
kept in the greenhouse, exposed to the 
full length of day of that season, until 
June 10th, about a month after germi-
nation. 
Beginning on June 10th a part of 
the plants were placed on small trucks, 
run outdoors at 8 :00 A. M. and re-
turned to a darkened room at 6.00 P. 
M. They were, therefore, exposed to 
a ten-hour day. Of the remaining 
plants, some were left in the green-
house and some kept constantly out-of-
doors near the trucks of plants receiv-
ing the short-day treatment. At ten-
day intervals for a time thereafter, 
some plants were removed from and 
others placed in the trucks. The dif-
ferent plants were thus subjected to 
the short-day treatment at various ages 
and for various lengths of time. 
The room used in this test was 
darkened by means of several thick-
nesses of heavy brown paper placed 
over the glass of the doors and win-
dows. \Vhile not perfectly dark, ob-
jects in the interior could be made out 
*Paper No. 116,' Department of Plant Breeding, Cornell University, Ithaca, New York. 
Chalco 
teOJiflte 
MAY JUNE JULY AUGUST SEPT. OCT. 
-:::: ::.:: :_- - _-_- - - - - - - - -:;:.;; - - - - - - - - -- - - - - - - -!. ---A 
- - - - - - - - - - - - s---
- - - - - - - - - - - - ~- - - -·A 
------------- --A 
- - - - - - - - - - - -A 
: -:. -_ - _-.: ..: :. - - - - - -A _ -A 
--------- S ---A 
:-::::::-::=- -::":A 
- - - - - - - - - - - - - - -- --·A 
JJlJra
nt9:{ ~~::-{:~-~=-~~ f{~=-=------ -: :~:-&~~ ::. -::: ::- -:: :. ---:. -----:.: =:.-f.:1·s teoslIlle ::- :- :: ::- ::- :: ::- = _- _ _ _ 5:"5 
- - - - - - - - - - - - s--
- - - - - - - - - - - - - - - -A 
FJo.rJdiJ. 
teosinte 
Perennial 
teosinte. 
I/ 
.Florida. 
teosinte 
x 
Naize 
Pr 
Perennial 
teosillte ( 
x ]'fa/ze 
::-:.-::::~:-: :.:....:.::---::-:::. ---:~-: ~_~.~:. :-.:::.:-::.::- .::: :::'-:'-:'--5-~ 
~ =-:.:_ :_=_=: ::: ----- :s~:~-_·: 
- - - - - - - - - - - - - - -5- --4 
- - - - - - - - - - - - - -5 A 
- - - - - - - - -. --·4 
-------- --'5---A 
- - - - -'- - -- - - - - - - - 5 
- - - - - - - - - .- - - - - A 
:::.-:-: :.::_::::::::.: :.-_ -_:. ::_-:::.:: :.:..:-_-_ : -:.. -_-:::::. ::_-_-.:~:.5·A 
------ ------------------------------5 
- - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - -·5 
=:-_-_-_-_-_:.::=----------- --- --- ------ -----·s 
---511:A 
5- -A 
5- - -
55 . 
-6--A 
:.::.::. ::: :::::-_-_=:::~_t=t=t-;---A 
:.:. -- :. ::. ---- ----------- ::gg=g3=~~g =8g=8S=%-s--::~ 
- - - - - - --- - - - - ---00-00-00-0 -00- OO-OC-5 
::: : .:- _- _-:: :..:-_ _ _ 4:5 __ -A 
- - - - - - - - - - - • - -- A 
-: :: _ -:. ::: _-_ :. :: _- _-_ -_ - 5- ~ 
-.... s .• 
--5A 
:I .• 
A 
- - - - - - -5- --A 
-------- -5---4 
- - - - - - -5- - - 4 
.::: --=-::-:::::-: -'-- -----::.: :5-~'A 
- - - - - -. - - - - - - - ·5 
------- ------ 5--'A 
- - - - - - - - ~-4 
- - - - - _. - - - . - ---
------- 5---A 
- - - - - - - -5-A 
- - - - - - -. -5- 4 
:.:. ::- _-_ -_ -_- :5S::~ 
- - - - - - - ·5··4 
- - - - - - - ~ --A 
~ ~~~~~~ :: ~:::-~i~;_~_+~S:~-A 
- - - - - - - - - - - - -ool-oo-oo-9,~ ~r-oo-q,!)\",!, 
:. :.:::-:: :.:: : :. -- ---- =~I=~~S~go-{l~=gg=-°OC~~A 
SHORT-DA Y TREATMENT OF TEOSINTE AND MAIZE 
FIGURE 23. Effect of short-day treatment on flowering date of teosinte, teosinte-
maize hybrids, and sub-tropical maize. The plants were started May 1 and grown 
in pots. Each .line represents a single plant. 
Explanation of symbols: 
- - - - - Exposure to full length of day. 
---- Ten hours in full light and 
+-+ 
iourteen hours in a dark 
room. 
- Ten hours in iull 
fourteen hours in 
darkened room. 
light and 
a partly 
o 0 - OOTen hours 111 full light 
and iourteen hours under canvas 
shade. 
S indicates date of appearance of silks. 
A indicates date of appearance of anth-
ers. 
Emerson: Short-Day Treatment of Teosinte 43 
with difficulty when the room was 
closed. To vary the test, some plants 
were placed, except for the ten hours 
of daylight, in a similar room that 
was partly darkened by green window 
shades, the glass in the doors not being 
covered. Still other plants were shaded 
bv means of a heavv canvas enclos-
i~g them at the top -and sides. The 
canvas was not securelv fastened and 
often gaped a few iri'ches admitting 
direct light. No determination of the 
intensity of light in the several dark-
ened or shaded roOI11S was attempted. 
It was found. however, that the light 
under the canvas at 6 :00 P. M. in 
mid-summer· was sufficient to enable 
one to read fine print fairly readily. 
Results of the Tests 
The result of the various short-dav 
treatments are perhaps best seen in th~ 
diagrams and photographs reproduced 
here. It is strikingly apparelit from 
the diagrams that in general, plants 
given only ten hours of daylight blos-
somed much earlier than those exposed 
for the full length of day. In case 
of teosinte and teosinte-maize hybrids 
the difference was usuallv more than 
two months, and for the sub-tropical 
maize practically one month. 
Perhaps the next most striking fea-
ture of the diagrams is that ten days 
of short-day treatment, beginning when 
the plants were only about a month 
old, had no effect whatever in hasten-
ing the flowering period. It does not 
follow from this, however, that a ten-
clay treatment begun later would have 
been without effect. The experiment 
gives no information on that point. 
A twenty-day treatment, on the con-
trarv. was almost as effective as treat-
mel{t for thirty, forty, or even fi fty 
days. 
Of the annual teosintes. Chalco was 
earliest, Durango next, and Florida last 
in coming into flower when given no 
treatment. And the same order of 
flowering was observed in general for 
these three varieties when exposed to 
a ten-hour day. Untreated peren-
nial teosinte pl~nts were slightry later 
than Durango plants and treated ones 
of approximately the same season as 
that annual variety. Hybrids of fair-
ly early stocks of maize with both 
Florida teosinte and perennial teosinte 
blossomed, on the whole, somewhat 
earlier than pure Florida teosinte and 
slightly later than perennial teosinte. 
\Vhile there are numerous exceptions 
to the statement, it can be said in gen-
eral that the later the short-day treat-
ment was begun the later the plants 
flowered. This is particularly true of 
Chalco teosinte, which showed silks in 
almost exactly thirty days from the 
time the treatment began, whether it 
started June 10th. 20th, or 30th. Peren-
nial teosinte flowered in from thirtv-
five to fortv davs when treatment w~s 
begun June- 10th, and in slightly over 
thirty days when begun June 30th and 
August 5th. Less prounounced and 
somewhat less consistent results from 
beginning treatment at different dates 
were obtained with Durango and 
Florida teosinte. In case of hybrids of 
maize with Florida and with perennial 
teosinte. silks appeared about five days 
later when the treatment was begun 
June 30th than when begun June 20th. 
Perennial teosinte plants and peren-
nial teosinte-maize hvbrids were the 
only ones tested in different degrees of 
darkness. In case of both of these, 
plants kept .in the partly darkened room, 
except for the ten hours of full day-
light. flowered at about the same time 
as similar plants put in the almost 
totally dark room ten days later. In 
other words, they responded to the 
treatment somewhat less quickly. \Vhen 
treated with the canvas shade, similar 
plants of these two lots flowered in 
about. seventy days as contrasted to at' 
average of about thirty-five days for 
the dark-room plants whose treatment 
began at the same time. It is interest-
ing to note. however, that even this 
canvas-shade treatment brought the 
plants into flower thirty-five to forty-
five days earlier than no treatment. 
From the information gained in this 
test. it should be possible, under simi-
lar conditions in the future, to start 
44 The Journal of Heredity 
FLORIDA TEOSINTE AFTER SHORT-DAY TREATMENT 
FIGURE 24. The plant at the left was given full daylight throughout the summer except 
for the ten days from June 10 to 20 when it was subjected to the short-day treatment, ten 
hours in daylight and fourteen hours in a dark room. It began flowering October 27, fifty-
one days after the photograph was taken. Evidently the short-day treatment for so brief 
a period in an early stage of development had no appreciable effect. The plant at the right 
was given the same short-day treatment from June 30 to July 30 and came into flower 
August 10, twenty-seven days before the photograph was taken. Photographs for Figures 
24-27 were made September 6, 1923. 
Emerson: Short-Day Treatment of Teosjnte 45 
PERENNIAL TEOSINTE AFTER SHORT-DAY TREATMENT 
FIGUR~; 25. The plant at the right received the full length of daylight throughout the 
summer and began flowering October 20, forty-five days after the photograph was taken. 
The plant at the left was ten hours in full daylight and fourteen hours in the shade of a 
canvas each day, from June 20 to September l, when it began flowering, five days before 
the photograph was taken. 
~--------------------------------------------------, 
HYBRIDS OF MAIZE AND PERENNIAL TEOSINTE 
FIGl:RE 26. The two plants at the right were in full daylight throughout the summer. 
The smaller plant grew in a very small pot under rather dry conditions out-of-doors and 
the larger one in a somewhat larger pot under moister conditions in the greenhouse. 
The former blossomed October 4 and the latter October 5, about four weeks after the 
photograph was taken. The plant at the left was given short-day treatment, by use of a 
dark room, from June 30 to July 30 and flowered August 4, or thirty-three days before 
the photograph was taken. The second plant from the left was given short-day treatment, 
by being kept under a canvas shade fourteen hours a day, from June 20 to August 31, 
when it flowered six days before the .photograph was taken. 
CHALCO TEOSINTE FORCED INTO FLOWER BY SHORT-DAY TREATMENT 
FIGt.:RE 27. The plant at the left was exposed to the full length of daylight of the 
summer. Its first flowers appeared September 28, or twenty-two days after the photograph 
was taken. The plant at the right was subjected to the short-day treatment, ten hours in 
iull daylight and fourteen hours in a dark room each day, from June 30 to July 30, and 
began flowering August 1, or thirty-six days before the photograph was taken. Its tassel 
was broken off. 
48 The Journal of Heredity 
teosinte plants and to begin the short-
day treatment at dates such. that they 
will flower within perhaps five days, 
one way or the other, of any date in 
mid-summer that may be set for their 
flowering. It should be noted, how-
ever, that there is nothing in these tests 
to indicate how much effect, if any, 
differences in temperature may exert in 
determining the flowering time. Ordin-
. arily the earliest of the writer's maize 
cultures, planted in the garden at 
Ithaca about May 15th, flower by July 
10th to 15th. In the cool summer of 
1923, they were ten days to two weeks 
later than that. Some seasons un-
treated Durango teosinte plants flower 
at Ithaca about the first of October. 
This year they were about two weeks 
later. Whether plants subjected to the 
short-day treatment would show simi-
lar differences in different seasons is 
not certainly known, but it seems likely 
that differences in temperature might 
have some effect. 
There is little in the writer's experi-
ence to suggest that differences in cul-
tural conditions have any noticeable 
effect on season of flowering. During 
the summer of 1923 Guatemala maize 
flowered at practically the same time 
whether grown in the garden or in 
relatively small flower pots in the 
greenhouse. Peruvian maize and Dur-
ango teosinte failed to show either 
silks o'r anthers in the garden at the 
time of the first killing frost, but the 
plants had reached practically the same 
stage of development, tasselling, as had 
similar potted plants in the greenhouse. 
Large types of tropical corn are, how-
ever, apt to develop fe~ or no ears 
when grown in small pots and peren-
nial teosinte plants seem more likely to 
have aborted tassels when thev have 
grown with little vigor. . 
The Physician's Part 
AERZTLICRE HEILKUNDE UND GEBUR-
TENRUECKGANG, by PROF. A. GROT-
JAHN, DR. MAX HIRSCH, GER. MED. 
RAT. PROF. DR. POSNER, OBERREG.-
RAT. DR. E. ROESLE, DR. GUSTAV 
TUGENDREICR. Pp. 54. Price, $0.45. 
Leipzig, Verlag von Curt Kabitzsch. 
1923. 
The purpose of this collection of 
brief papers is to consider what the 
medical man can do in the practice of 
his profession to check ti)e falling 
birth-rate. The subject is discussed 
from various aspects, but the most im-
portant papers are those of Dr. Posner 
on the treatment of men, and of Dr. 
Hirsch on the treatment of women. 
The chief problem is that presented 
by sterile marriages, of which, accord-
ing to current statistics, there are ten 
to twelve per cent in Germany, four-
teen per cent in the United States. 
twelve and one-half per cent in France. 
Dr. Hirsch, an experienced gynecolo-
gist, thinks the figure for Germany is 
too low, and that "of 500,000 mar-
riages, which on the average are year-
ly contracted in Germany, 100,000 are 
sterile." 
From the point of view of mere 
quantity, it would be desirable to cure 
the sterility of these matings. From a' 
truly eugenic point of view, the ster-
ility of a large part of them is socially 
advantageous, and too great success of 
the medical profession would be un-
fortunate.-P. P. 


Control of Flowering in Teosinte: Short-Day Treatment Brings Early Flowers

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Control of Flowering in Teosinte: Short-Day Treatment Brings Early Flowers

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