THE IXFLUEXCE OF AGE AXD CONDITION OF THE TREE UPON SEED 

 PRODUCTION IN WESTERN YELLOW PINE. 



TESTS ON WESTERN YELLOW PINE SEED. 



The influence of the character of the mother plant upon the quahty 

 and quantit}^ of seed produced and upon the character of the offspring 

 is a factor which is well recognized in plant breeding. In forestry 

 this factor should be considered not only in collecting seed for arti- 

 ficial propagation, but also in the selection of trees to provide for the 

 natural regeneration of cut-over areas. In selecting seed trees the 

 forester must ask liimself : ''Wliich trees ^^ill produce the best quaHty 

 and the greatest quantity of seed ?"' and finally, '^ Wliich will produce 

 the most desirable seedlings?" Secondar}^, though very important, 

 considerations wliich should govern the forester in liis selection of 

 trees to provide for the future stand after cutting are wind firmness 

 and merchantable deterioration or appreciation. 



This circular deals primaril}' ^vitli the conditions affecting the 

 germinative quahty of the seed. The influence upon the quantity 

 of seed, though of great importance, ^vl\l be treated only as a second- 

 ary topic, because the data on this phase of the subject are incomplete. 



The species studied was western yellow pine {Pinus ponderosa). 

 The locality was near Maine, Ariz., on the Tusayan National Forest, 

 elevation about 7,200 feet. In November, 1909, 100 samples, each 

 consisting of from about one-tenth to 1 bushel of cones, according to 

 the amount available, were collected from 100 trees representing 

 different ages, sizes, and conditions of soundness and general health. 

 The cones were collected in connection with a logging operation, which 

 made it possible to determme accurate!}^ the age and soundness of 

 the tree. In the case of young trees which were not feUed the age and 

 soundness had to be estimated; but since the number of such trees 

 was small and nearly aU of them were tlirifty, the errors in these esti- 

 mates ^vill not be great enough materiaUy to affect the results. In 

 each case the sample was made up of cones from aU parts of the 

 crown. Careful data were taken on each sample, according to the 

 outhne on page 4. ^ 



> The seed samples and accompanying data were gathered by Forest Assistant Harold H. Greenamyre. 

 163a3°— [Cir. 196]- 12 (3) 



