July 28,1923 
Growth of Fruiting Parts in Cotton Plants 
205 
Table X. — Volume, green weight, and dry weight per boll at 5-day intervals of Pima 
cotton at Sacaton , Ariz., IQ 2 I, based on the average of 60 bolls of each age that flowered 
in August 
| Age of boll. 
Volume. 
Green weight. 
Dry weight. 
1 Days. 
Cc. 
Gm. 
Gm. 
s 
.87 
. 72 
. 12 
IO 
3 - 
2. 96 
•45 
15 
8. 91 
7 * 93 
I. 26 
20 
12. 59 
11. 02 
1. 99 
2 5 
14. 66 
12. 86 
2. 56 
30 
14. 60 
12. 93 
2. 82 
35 
14 - 65 
I 3*03 
3. 12 
40 
14. 90 
L 3 * 45 
3-36 
! 45 
14. 80 
* 3 * 15 
3 - 76 
5 ° 
14. 65 
13. 16 
3-98 
55 
14. IO 
12. 14 
3 - 99 
60 
10. 30 
0-83 
! 65 
i 
1 4 - S 3 
3-99 
1 Open bolls. 
MATURATION PERIOD OF PIMA BOLLS 
A range in the period of maturation from 45 days to 80 days was 
obtained on normal Pima bolls in this study, with the period lengthening 
for the bolls of later flowering dates. This is in agreement with results 
reported by King, 5 who found that the period of maturation of Pima bolls 
in Phoenix, Ariz., varied from 54 days for those bolls set in July to 82 
days for those set in September. Sufficient data were secured in 1921 
on bolls of different flowering dates to indicate that at least three factors 
are involved in the lengthening of the period of maturation of Pima 
bolls at Sacaton. First, the early bolls were smaller than those set later 
in the season; second, the early bolls attained full structural develop¬ 
ment in fewer days than those set later; and third, the early bolls showed 
a more rapid reduction of the boll moisture after reaching mature struc¬ 
tural development, so that the opening stage was reached in fewer days. 
GROWTH OF SEA ISLAND AND MEADE COTTON BOLLS IN SOUTH 
CAROLINA 
The growth of Sea Island and Meade bolls near Charleston, S. C., in 
1922, is shown in Table XI, which gives the mean volume and weight 
per boll of 50 boll samples collected at seven-day intervals. It can be 
readily seen from this table that the bolls grow very rapidly to full size, 
as in the other experiments. The Sea Island bolls reach their mean 
maximum volume of 19 cc. at 21 days of age, and the Meade bolls also 
attained their larger volume of 29 cc. in the same number of days. 
In comparing the time required for bolls to reach full size, these data 
are only slightly different from those obtained with the Lone Star variety 
at Greenville, where the full size was reached in about 20 days. There is 
more contrast with the data secured from the Pima cotton at Sacaton, 
where the mean maximum volume was found to be reached at the age 
of 25 days. 
h King, C. J. water-stress behavior of pima cotton in Arizona. U. S. Dept. Agr. Bui. 1018, 24 p., 
3 fig., 4 pi. 1923. Literature cited, p. 23-24. 
