THE INFLUENCE OF AGE AND 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 quality 

 and quantity 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 himself: "Which trees will produce the best quality 

 and the greatest quantity of seed ?" and finally, "Which will produce 

 the most desirable seedlings?" Secondary, though very important, 

 considerations which should govern the forester in his selection of 

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

 and merchantable deterioration or appreciation. 



This circular deals primarily with the conditions affecting the 

 germinative quality of the seed. The influence upon the quantity 

 of seed, though of great importance, will 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 determine accurately the age and soundness of 

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

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

 was small and nearly all of them were thrifty, the errors in these esti- 

 mates will not be great enough materially to affect the results. In 

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

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

 outline on page 4. * 



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

 16333 [Cir. 196J- 12 (3) 



