284 



SEEDING AND PLANTING 



nate during the energy period in germination tests. As a general 

 rule, tree per cent and utilization value based upon germination 

 tests are much closer together in species having large seed than 

 in species with small seed. 



Applying the above formula, white pine seed with a germina- 

 tive energy of 0.55 in 40 days, with 26,800 seeds per pound and a 

 tree per cent equal to 0.8 of the utilization value based on germi- 

 native energy will require 6.3 pounds of seed to sow 500 square feet 

 of seedbed at a density that will give 150 plants per square foot, thus 



500 X 150 



S = 



= 6.3. 



0.55 X 0.8 X 26,800 



Where germination values are not available experience has 

 shown that the fresh seed of large-seeded conifers like western 

 yellow pine when sown under excellent seedbed conditions has an 

 average tree per cent value of 50 to 65. In other words, there 

 should be expected in the seedbed from one-half to two-thirds as 

 many plants as there was seed sown. Smaller-seeded species like 

 white pine and spruce when sown under similar conditions have 

 a tree per cent value of 25 to 50. There should be expected from 

 one-fourth to one-half as many plants as there was seed sown. 



The following table based upon the number of seeds per pound, 

 the tree per cent value of fresh seed of average viability, and the 

 number of seedlings per square foot of seedbed gives the amount 

 of seed required for 500 square feet. When a larger or smaller 

 area is sown or a larger or smaller number of seedlings are desired 

 per square foot or when the tree per cent value of the seed is higher 

 or lower than the average the amount of seed required for any area 

 can be found by making the proper substitutions in the formula. 



