A METHOD OF NUMBEEING PLANTS IN 

 PEDIGEEE CULTURES^ 



DR. HOWARD B. FROST 



Instructor in Plant Breeding, Graduate School of Tropical 

 Agriculture and Citrus Experiment Station, 

 University of California 



About fifteen years ago, Dr. H. J. Webber (1906, p. 

 308) introduced into the plant-breeding work of the United 

 States Department of Agriculture a simple and convenient 

 method of pedigree numbering. This method has. three 

 essential features: (1) the use of an initial series num- 

 ber" for each hereditary line or group of lines, the sets 

 of series for different crops being numbered separately ; 

 (2) the use of letters for particular parental combinations 

 in a hybrid series; (3) the use of numbers separated by 

 dashes to designate individuals of successive generations. 



For example, with cotton. Series 1 might represent 

 selection for longer lint, within tlio vnrlety Columbia; 

 1-1, 1-2, etc., would then designate tlio \)]nu{< first selected 

 (Pi generation), and 1-1-5 would designate a plant of the 

 second or Fj generation. 



Similarly, Series 2 might represent a cross between two 

 varieties (for example, Columbia $ X Truitt c^), and 

 Series 3 the reciprocal of this cross. Each combination 

 of "individuals" (plants, branches, or single flowers, as 

 desired) witliin a hybrid series is represented by a letter, 

 as in 2A, 2D. The F, plants are then designated by num- 

 bers written after the letters, as in 2A1, 2D6, and the num- 

 ])(']•>' for later u-enei'ations follow dashes exactly as in a 

 non-liyl)i-id series (for example, 2A1-5). The use of 

 letters thus characterizes hybrid sei-ies. 



This system of numbering. ' ' - / ■ linear pedi- 



