952 
Journal of Agricultural Research 
Vol. XXVIII, No. 9 
The Acala variety is somewhat like Durango in habits of growth, but usually 
with shorter stalks and less tendency to the “cluster” habit of short fruiting 
branches. The central stalk is fairly strong and the plants seldom become 
completely prostrate late in the season, even when heavily loaded with bolls 
(Pl. 1, D). Its ability to set bolls rapidly and to mature large crops under short- 
season conditions or when planted very late are important features. 
The Lone Star and Mebane (PI. 2, A and B) varieties representing the Texas 
big-boll type are very similar in their habits of growth, being lower and more 
compact than the preceding varieties, but with rather long spreading vegetative 
branches, short jointed stalks, large leaves and bolls. While these varieties 
often produce large yields under irrigated conditions, they frequently present 
difficulties in picking on account of the rather weak and flexible stalks which 
often lodge badly, so that many of the bolls lie on the ground where they may 
be mildewed or rotted, or the fiber stained by contact with soil. 
Plats of the Pima, Hartsville, and Acala varieties are shown in Plate 3, A, 
B, C. 
The average height of the 25 plants of each variety in 1923 which is shown in 
Table V represents fairly closely the relative height which plants of these varie¬ 
ties attain when grown on moderately fertile soils under irrigation. 
SUMMARY 
Adjacent plantings of Pima Egyptian and several Upland varieties of cotton 
were made at Sacaton, Ariz., from 1920 to 1923, and data of plant behavior 
secured on habits of growth, flowering, shedding, yields, and lint and boll char¬ 
acters. A series of measurements on selected groups of 25 plants of each variety 
were conducted through the seasons of 1922 and 1923. 
From these data it appears that the active growing and flowering periods of 
the Lone Star and Mebane varieties were much shorter than those of Pima, 
Hartsville, Durango, or Acala. The Pima plants continued growth over a 
longer period than any other variety, but in 1922 and 1923 had a somewhat 
shorter period of flower production than some of the Upland varieties. 
The Upland varieties began flowering and fruiting earlier, and produced a 
greater number of flowers during the season than the Pima variety, but on 
account of more extensive shedding among the Upland varieties they brought 
fewer bolls to maturity. In 1922 the 25 plants of Acala produced a total of 
1,948 flowers, which was the greatest number recorded for any variety, but only 
579 bolls were retained, whereas 25 Pima plants produced 1,093 flowers, of which 
902 became mature bolls. 
The highest shedding rate, 74.4 per cent, was recorded for Lone Star in 1923, 
while the lowest rate was for Pima, in 1922, which shed only 17.5 per cent of the 
young bolls. 
The low shedding rate of Pima enabled that variety to produce yields which 
compared favorably with those of Upland cotton, notwithstanding the more 
abundant flowering and larger bolls of the Upland varieties. 
The average age at which bolls of the Upland varieties shed was about 7 days, 
while the average age of shedding for Pima bolls was 10 days in 1922 and 9 days 
in 1923. 
The longest mean period of boll development recorded was 62.3 days, which 
was required by bolls developed from flowers of Pima cotton produced from 
July 6 to September 10, 1923. The shortest mean period was 47.1 days, which 
was recorded for Durango bolls developed from flowers produced from June 29 
to August 21. The mean periods required for bolls of four other Upland varieties 
were Hartsville 54.3, Acala 51.5, Mebane 50.5, and Lone Star 51.0 days. 
