May 10, 1924 
Length of Fiber from Bolls at Different Heights 
565 
It may be concluded, therefore, that bolls borne on the lower fruiting branches, 
constituting the so-called “bottom crop,” produce shorter fiber than bolls that 
are situated higher on the plant. 
Another series of determinations of fiber length was made on bolls from flowers 
which had opened in successive periods during July and August, 1921, the object 
having been to ascertain whether there is a consistent relation between the 
length of the fiber and the date of opening of the flower from which the boll 
developed, regardless of the height on the plant of the fruiting branch on which 
the boll was borne. In this case also fiber was measured on one seed from each 
boll. 4 * The data obtained are given in Table III. 
Table III. — Mean length of Pima cotton fiber in bolls from flowers which had 
opened during successive periods in 1921 
Dates of flowering 
Mean 
length of 
fiber 
Dates of flowering 
Mean 
length of 
fiber 
July 22 to 24.. 
Millimeters. 
39. 59 ±0.33 
41.90± .20 
41. 36± .33 ! 
Aug. 14 and 15_ 
Millimeters 
41.09 ±0.32 
41.72± .29 
July 27 to 30... 
Aug. 23 and 26... 
Aug. 8 to 10.___ 
The fiber from flowers opening during the first period (July 22 to 24) is sig¬ 
nificantly shorter than that from any of the later flowers but there are no signifi¬ 
cant differences in fiber length among any of the later periods. It is probable 
that the flowers which opened during the period July 22 to 24 were borne, for the 
most part, on low fruiting branches, while flowers which opened later may have 
been borne either on higher branches or on nodes farther out on the lower fruiting 
branches. 6 
While generalization from such limited data is unsafe, these results, as com¬ 
pared with those given in Table II, point to the conclusion that the length of 
fiber is affected less by the date of flowering than by the height on the plant of 
the fruiting branch on which the boll is borne. 
4 Through an oversight, no record was made of the numbers of determinations on which are based the 
means for each period. 
6 W. Lawrence Balls studied in Egypt the relation between date of flowering and length of fiber, taggin g 
20 flowers daily from July 7 to September 1. His data (Balls, W. L. the development and properties 
of raw cotton, p. 198-203, Tables I—II; p. 90, fig. 4, London, 1915) show marked fluctuation during the 
flowering season, the minimum length of fiber having been reached in bolls from flowers opening during the 
5-day period July 27-31 and the maximum length in bolls from flowers opening during the 5-day period 
August 9-13. The difference in fiber length as between the two periods amounted to 2.9 mm. 
