UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No. 1092 
Ji^&'^WU 
Washington, D. C. 
PROFESSIONAL PAPER 
September 21, 1922 
PEDIGREED FIBER FLAX. 
By Robert L. Davis, Assistant Plant Breeder in Fiber Investigations, 
Bureau of Plant Industry. 
CONTENTS. 
Introduction 
Early selection work 
Elimination of poorer selections 
Comparing with the check by per- 
centages 
Using the score card for the elimi- 
nation of the poorer selections 
Improvement by cross-pollination 
Instruments devised for use in 
breeding flax 
Page. 
1 
4 
6 
Page 
Commercial test of pedigreed fiber- 
flax strains 
Increasing the quantity of pedigreed 
seeds 19 
Seed increase by growing two crops 
a year 21 
Summary 21 
Bibliography 23 
16 
V 
INTRODUCTION. 
The object of the work described in this bulletin has been to im- 
prove the seed used in the fiber-flax industry and particularly to de- 
velop by selection a long-stemmed flax that would increase the yield 
of fiber per acre. 
In this work all plants that originate from the seed of a single 
plant or direct descendants from a single plant are known as a 
selection. This definition must be qualified so as not to include the 
progeny of a hybrid. Selections are retained only when the plants 
are uniform. Flax is a self-pollinated plant, and it is therefore 
relatively easy by means of selection and propagation of individual 
plants to secure strains that are uniform. 
The need for selecting long-stemmed strains of fiber flax appears 
more obvious than that for selecting high seed-yielding strains of 
wheat or other grain crops. A bushel of grain is always market- 
able, no matter how low the yield may be, but short fiber-flax stems 
have very little value, because they are difficult to harvest and work 
up into fiber. The general crop of fiber flax produces a stem of satis- 
factory length not more than two years out of three ; hence the need 
for a tall variety that will yield a good stem length even in unfavor- 
107389°— 22 1 
