200 
Journal of Agricultural Research 
Vol. XXV, No. 4 
between squares on the first and second nodes of branches farther up on 
the main stalk. The mean interval between the appearance of squares 
on the fourth and fifth nodes was 6.2 days, while the mean interval be¬ 
tween the appearance of squares on the first and second nodes was 6.05 
days, for squares appearing within the three-week period of July 6 to 
July 26. 
Table IV .—Average interval between the successive appearance of squares for each inter - 
node on 10 Pima plants , Sacaton, Ariz., IQ22 
Internodes. 
Interval. 
First to second. 
Days . 
5-65 
6. 01 
7 . 30 
Second to third. 
Third to fourth. 
Fourth to fifth..'. 
/• oy 
6. 82 
DEVELOPMENT PERIOD OF THE FLORAL BUD OR “SQUARE'* 
The number of days from the appearance of a square 4 until it flowers 
is a feature in the growth of cotton that has received little attention by 
investigators, although it is of considerable importance in the analysis of 
late or early varieties and in relation to weevil damage. 
In the season of 1921, the “square period ”—as the interval between 
the appearance of the square and the date of flowering has been termed— 
was recorded for several varieties of cotton at Sacaton, Ariz. The infor¬ 
mation was obtained on three Upland varieties for squares that appeared 
between June 15 and July 10 and for squares of Pima cotton between 
June 15 and August 15. (See Plate 1, showing the early development of 
Pima floral buds.) These data are presented in Table V, giving the 
mean square period as obtained from the above data. It will be noticed 
that the mean period for Pima was 30.11 days, while that of the three 
Upland varieties was about. 23 days, a difference of approximately 7 
days. From similar data obtained on James Island, near Charleston, 
S. C., the mean square period for Sea Island was found to be 33.06 days 
and for Meade cotton 28.45 days. Such data illustrate in a practical 
way one of the principal reasons why the Sea Island and Egyptian types 
of cotton are later than the Upland varieties. 
Table V. —Interval from appearance of squares until flowering date 
Variety. 
Locality. 
Year. 
Mean square pe¬ 
riod. 
Lone Star. 
Sacaton, Ariz. 
1921 
1921 
1921 
1921 
1922 
1922 
Days. 
23. 20±0. 337 
22. 8o± . 230 
23. 40 it .232 
30. 11 ± . 128 
33. 04±. 127 
28. 45 ± . 104 
Acala. 
Durango... 
.do. 
Pima Egyptian. 
.do. 
Sea Island. 
South Carolina. 
Meade. 
.do. 
4 The term "appearance of a square" is used in this paper to designate the time that the three bracts of 
a fruiting bud become visible to the naked eye as a minute triangular form, approximately one-thirty- 
second inch in diameter. 
