812 
Journal of Agricultural Research 
Vol. XXX, No. 9 
seed produced; but it appears that this 
is true only when dealing with beets 
which tend to be vegetative or are 
“trotzers.” 
The increase in production of seed in 
proportion to the increase in number of 
seed stalks per beet agrees well with 
the results of other investigators. 3 
The increase in the number of seed 
stalks per beet is probably due to the 
inhibition of the terminal bud during 
the early growth period and the mobil¬ 
ization of an excess of available food 
material which gives the outer crown- 
buds time and favorable opportunity 
for development, thereby giving rise to 
an increased number of seed stalks. 
Further evidence of this is given by the 
fact that single or few seed stalks can 
be developed on beets at will. As a 
result there occurs the single or few 
seed stalk habit of annual or bolting 
beets, mother beets which are planted 
in the heat of summer, mother beets 
with outer crown buds destroyed due 
to excessive drying, and also annual 
or mother beets which are subjected to 
forced reproduction in the greenhouse 
at high temperatures. The factors 
which lead to the single or few seed 
stalk habit of beets are those which 
tend to immediate reproduction, thus 
forcing the terminal and retarding the 
outer crown buds. 
Plate 1 shows that the seed spikes, 
seed balls, and floral bracts vary con¬ 
siderably with the period of year the 
beets are planted. Beets planted early 
tend to produce compact seed spikes 
and large seed balls, with small bracts 
or none. Beets planted later in the 
season tend to produce elongated 
floral stalks, smaller seed balls, and an 
increased number of larger seed bracts. 
The seed bracts on the beets planted 
in July and August tend toward 
vegetative leaves, and are much en¬ 
larged. If beets planted as late as Sep¬ 
tember produce seed stalks, they are of a 
vegetative rosette type, as illustrated in 
Plate 1, E. These data indicate that 
later planting results in a tendency for 
beets to be more vegetative even when 
producing seed. 
The rate of development of seed 
stalks and seed is given in Table II. 
The reproductive development was 
greatly retarded in the beets that were 
planted early, as indicated by the days 
elapsing from time of planting to time 
of flowering. Beets planted in the 
heat of summer tended to produce seed 
within a short period, while beets 
planted in the fall were very irregular 
in seed production and did not tend to 
develop reproductive organs. Photo- 
periodism experiments were arranged 
in the hope of finding some explanation 
of this increased seed production 
resulting from early planting. Both 
individual beets and lots of beets were 
exposed to the various lengths of days 
during spring, summer, and fall. An 
increased length of days during the 
spring had no noticeable effect upon 
the beets up until June 1, two months 
after planting. It was evident that 
there were other more important 
factors limiting the growth of reproduc¬ 
tive organs during this period. From 
June 1 on, the seed stalks of beets 
subjected to light were probably more 
of a seed type, and flowered about one 
week earlier than beets not subjected 
to light. Beets planted late in the 
season and exposed to increased il¬ 
luminations made more rapid seed- 
stalk growth and tended toward more 
reproductive seed stalks with greater 
per cent of late seeds. This is well 
illustrated by an individual beet (pi. 
2, A) planted in August, the right side 
of which was exposed to six hours extra 
illumination from Sept. 8 to Oct. 15. 
It thus appears that light is an impor¬ 
tant factor in the lengthening of seed 
stalks when other limiting factors are 
not present. 
Table II .—Development of seed stalks 
and seed , 1922-23 
Time of 
planting 
Time 
required 
to reach 
final 
height 
Time after 
planting 
beet to 
date of 
first 
flowering 
Length of 
flowering 
period 
Days 
Days 
Days 
Mar. 1_ _ . 
120 
113 
17 
Apr. 1_ 
90 
82 
19 
May 1_ 
60 
52 
24 
June 1_ 
45 
42 
25 
July 1- 
30 
30 to 60 
20 to 75 
Aug. 1- 
Sept. 1 
30 
Irregular 
Indefinite 
i 
1 
The meteorological data as to wind 
movement, relative humidity, and 
evaporation, gave no further explana¬ 
tion than did the effect of increased 
illumination. While these are all of 
importance, there seems to be other 
more important factors which require 
consideration. It was not until the 
beet roots were removed at different 
periods during the season that it was 
learned that those beets which produced 
the best quantity and quality of seed 
had previously produced the most 
marked root development. 
Plates 2 and 3 show the root develop¬ 
ment of beets planted from April to 
3 Harris, F. S., and Hogenson, J. C. some correlations in sugar beets. Genetics 1: 334-347. 
1916. 
