Mar. 34, 1923 
Summer Irrigation of Pima Cotton 
939 
Ewing 8 found in comparing the flowering curves of Trice cotton, from 
one plot on rich soil and another plot on poor soil, that— 
the same daily fluctuation in the flowering curve is noticeable in the two situations, 
and the most pronounced difference is in the height of the flowering curve. 
This would agree with the results shown in figure 2, although instead of 
the soil being different the moisture supply was varied in our experiment, 
and as the moisture did not appreciably influence the rate of flowering 
the curves are not very different. 
That the number of flowers per day was not noticeably affected by 
irrigation will be apparent from the diagram (fig. 4), which gives the 
daily flower production and the dates of irrigation for the three borders 
of series II. The behavior of the plants in this series is regarded 
as sufficiently representative of the other two series. There was no 
consistent behavior in either higher or lower rates of flowering at any 
regular interval after irrigation. This is in direct contrast to a common 
belief in the irrigated valleys of the Southwest that fewer flowers are 
produced for a few days after each irrigation, but no such relation is 
shown in the curves of figure 4. 
It is recognized that the physical condition and size of the plants, 
fertility of the soil, and the amount of available moisture, undoubtedly 
are factors which limit the number of flowers produced; but from the 
data presented in figure 3 and figure 4, it seems that other influences not 
yet identified must determine whether the numbers of flowers on parti¬ 
cular days shall be relatively high or low; and since it is possible to 
predict when a bud will flower one day and sometimes two days before¬ 
hand, it is evident that the determining influences are effective at least 
several days in advance. 
SHEDDING OF YOUNG BODES 
The sheddipg of young bolls began on July 14, but up to July 29 the 
rate was almost negligible, amounting to less than 1 shed boll per day 
for every 50 plants. A higher rate occurred during most of August, the 
highest number falling on August 12, but an average of the period when 
the maximum shedding occurred showed less than 1 shed boll per day 
for every 7 plants. During the latter part of August and the first two 
weeks in September the rate fell to less than 1 shed boll per day for 25 
plants. 
The daily shedding records for the 25-plant sections are given in Table 
VII, which gives the number of young bolls shed per day in each border, 
the total per day for all borders, the total per border for the season, and 
the percentage for each border. 9 The age of the bolls when the maximum 
shedding occurs is given in Table VIII, showing the number of days 
between the opening of the flowers and the shedding of the young bolls 
within a period of 30 days after flowering, with the number of bolls shed 
for each interval of days per border and the total for all borders. 
8 Ewing, E. C. a study off certain environmental factors and varietal differences 
influencing the fruiting of cotton. Miss. A gr. Exp. Sta. Tech. Bui. 8, 93 p., 40 fig. 1918. litera¬ 
ture cited, p. 93. 
9 Diagrams of the shedding on series II, including borders C1-9, Ci-10, and Ci-n, from July 14 to Septem¬ 
ber 15, derived from the data in Table VII, are shown in figure 3, where they are used for purposes of com¬ 
parison with the flower diagrams and in relation to the dates of irrigation. 
