Mar. 24 ,1923 
Summer Irrigation of Pima Cotton 
935 
growing season the average height that finally was reached by the “nor¬ 
mal” borders (52.1 inches) was little different from that obtained in 
the “heavy” borders (52.9 inches) or in the “medium-heavy” borders 
(54.8 inches). There was no indication that the different amounts of 
moisture had affected the rate of growth, though it should be remem¬ 
bered that at no time was the amount of moisture allowed to get so low 
that the plants suffered noticeably, even in the “normal” borders that 
received the least water. The conclusion is that the additional or sur¬ 
plus water applied to the other borders was not utilized in making larger 
plants. 
Table V .—Average height in inches of 25 plants in each border by weeks from fuly 8 to 
September g 
Normal irrigation. 
Medium-heavy irrigation. 
Heavy irrigation. 
Date. 
Cr- 3 . 
C1-9. 
Ci-12. 
Aver¬ 
age 
in¬ 
crease 
per 
week. 
C1-4. 
Ci-10. 
Ci-13. 
Aver¬ 
age 
in¬ 
crease 
per 
week. 
Ci-s. 
Cx-xx. 
Cx-I 4 - 
Aver¬ 
age 
in¬ 
crease 
per 
week. 
July 8. 
15. 
25 - 6 
29.9 
34. 2 
28. 0 
23-4 
27. 6 
4 -1 
26.1 
30.9 
26.3 
29.4 
24. 2 
30-3 
4 - 7 
23.8 
27.1 
25-4 
28. 7 
26. 1 
29.1 
3 - 2 
22. 
36. s 
34-0 
32. 6 
5-8 
36.4 
35 -i 
35-4 
5-4 
32.0 
34-3 
34 - 8 
5-4 
39 . 
40. 6 
38. 7 
36.3 
4. 2 
41. 6 
39-9 
40-3 
5 -o 
38. 2 
41. 0 
40 -3 
6. T 
Aug. 5. 
44-3 
44-8 
40.5 
4*7 
46.3 
43-4 
44.6 
4 -1 
42.9 
47 -o 
45 - 8 
S -4 
3-8 
.8 
12. 
45-8 
48. 0 
43-8 
2. 6 
50. 0 
47-4 
49-4 
4-2 
45*2 
SI-2 
50. 6 
19. 
47-4 
49.0 
44.4 
1.1 
51-0 
49.0 
50 - 0 
I. X 
45 - 9 
52-4 
51-3 
26. 
SO- O 
Si -5 
46.3 
2.4 
52-5 
Si -4 
Si- 7 
1.9 
46. 6 
54 -o 
52. 6 
1.3 
Sept. 2 .. 
52 . 0 
54-3 
47 - 7 
2.0 
55-8 
S 3-4 
S 3-4 
2.3 
48. 2 
56. 2 
S 3-4 
i-S 
9 . 
! 53-2 
I 
54-6 
48. s 
.8 
56. 8 
54 * O 
53-8 
•7 
48.6 
56. 8 
S 3-4 
• 2 
Under some conditions the absence of any appreciable or consistent 
difference in the development of the plants in any of the treatments 
might be ascribed to lack of soil fertility. This possibility was considered* 
but the fact that in the previous year cotton has grown 6 to 7 feet tall 
on some of the land included in series II and III is thought to be sufficient 
evidence of an abundance of available plant food. Hence it is believed 
that the general uniformity of growth should be attributed to the stage 
of development the plants had attained before irrigation began rather 
than to the state of fertility of the soil or subsequent influences. 
It is to be recognized, of course, that with other seasonal conditions, 
as hot weather in the spring or heavier rains in the summer, such uni¬ 
formity of behavior might not have been maintained; but this does not 
make it less important to know how uniform the behavior may be under 
favorable conditions and how little difference was secured by such varied 
frequencies of irrigation as were included in this experiment. 
DAILY PRODUCTION OF FLOWERS 
The first flowers appeared early in July, and the record of flower produc¬ 
tion was started on July 6. At this time there were only 2 or 3 flowers 
opened per day on 25 plants, but the rate rapidly increased with the 
growth of the plants. The highest production was reached on July 31, 
with a maximum period extending for approximately 20 days, beginning 
about July 28 and ending about August 17. During this period an aver¬ 
age of about flowers per plant per day was sustained. On September 
