UNITED STATES DEPAilTMENT OF AGRICULTURE 



BULLETIN No. 1092 i 



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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 1 



Early selection work 4 



Elimination of poorer s-elections 6 



Comparing with the check hy per- 

 centages 9 



Using the score card for the elimi- 

 nation of the poorer selections 10 



Improvement by cross-pollination 14 



Instruments devised for use in 



breeding flax 16 



Page. 



Commercial test of pedigreed fiber- 

 flax strains . 17 



Increasing the quantity of pedigreed 



seeds 19 



Seed increase by growing two crops 



a year 21 



Summary 21 



Bibliography 23 



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 imf avor- 



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