UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT BULLETIN NO. 1365 
Washington, D. C. 
March, 1927 
DEVELOPMENT OF FLOWERS AND BOLLS OF PIMA AND 
IN RELATION TO BRANCHING 
<-> » jw 
By H. F. Loomis, Assistant Agronomist, Office of Cotton, Rubhgfriand^Other 
Tropical Plants, Bureau of Plant Industry 
i «OM£ ECOtfOJfJ. 
iJiCALA COTTON 
SB A. ^ 
CONTENTS 
Page 
Introduction 1 
Procedure in taking field notes 2 
Production of squares and bolls on Pima and 
Acala plants 2 
Determining periods of square and boll 
development.. _ 7 
Development of squares on specific nodes of 
fruiting branches _ 7 
Square and boll records for specific nodes of 
fruiting branches borne by main stalks... 10 
Square and boll records for specific nodes of 
fruiting branches borne by vegetative 
limbs.. 16 
Page 
Shedding of squares from specific nodes of 
fruiting branches.. 18 
Boll shedding from specific nodes of fruit- 
ing branches 21 
Development of bolls on specific nodes of 
fruiting branches 22 
Boll periods affected by fruit on preceding 
nodes. 24 
Practical application of the data to cotton 
growing 25 
Summary... 25 
Literature cited 27 
INTRODUCTION 
A study of Pima Egyptian cotton in comparison with Acala, an 
upland variety now grown extensively in the Southwestern States, 
has been in progress at the United States Field Station, Sacaton, 
Ariz., for several years. The results of this comparison are not 
complete, but many notes taken during the seasons of 1924 and 1925 
furnish data that are of interest in connection with general studies of 
the cotton plant. These data are presented in this bulletin and 
refer principally to the development of the fruiting parts of the 
plants — the floral buds, flowers, and bolls — in relation to their 
positions on the fruiting branches. 1 The developmental periods and 
the abscission of the buds, flowers, and bolls have been found to 
differ with different positions on the fruiting branches. Differences 
between the two varieties of cotton, as shown by the data, indicate 
the possibility of determining many points relating to cultural prac- 
tices and to the comparative value of varieties under these practices. 
i This bulletin forms a continuation of the studv of fruiting parts of cotton made by Martin, Ballard, 
and Simpson (17). Other important phases of flower and boll development not dealt with or specifically 
mentioned in this bulletin have been described by Allard (1), Balls (2 and 8), Barre (4), Ewing (10), Har- 
land (m, King (12, 13), King, Loomis, and Varmette (14), Lloyd (15, 16), Martin, Ballard, and Simpson 
(17), Martin and Loomis (18), Mason (19), and Zaitzev (21). Italic numbers in parentheses refer to 
"Literature cited," p. 27. 
23914°— 27 1 
