SEED CHARACTERISTICS IN CONIFEROUS FORESTS 7 



continued over several seasons. Instances of field sowing of Douglas 

 fir and sugar pine have been found where the results were considered a 

 failure the first season after sowing, and some germination appeared the 

 second season, while the third season produced a very satisfactory germina- 

 tion. While this may occur under favorable conditions of sowing, the 

 length of the dormancy period in nature under an environment less 

 favorable for germination is still further prolonged. 



SIZE OF SEED 



That the early development of the seedling is dependent on the food 

 stored in the endosperm of the seed was shown by tests of seed of western 

 yellow pine, Douglas fir, western hemlock, and western red cedar, in sand, 

 in soil to which nutrient solutions had been added, and in potting soil 

 made up of leaf mold and sand. The following nutrient solution was used: 



To each liter of water was added: 



1 . gram calcium nitrate 

 0.25 " potassium chloride 

 0.25 " magnesium sulphate 

 0.25 " acid potassium phosphate 



The soil was moistened with this solution and always watered with the 

 same solution. 



The seeds germinated equally well under all conditions, but the dif- 

 ferences were very soon noticeable after germination. 



Seedlings germinated in the sand came above the ground and appeared 

 as good as those grown in the potting soil or in the nutrient solution. When 

 the seed-coats were shed, they began to fail and apparently were unable 

 to get any nourishment, or at least not sufficient to make any growth. 

 After the cotyledon stage, these seedlings did not appear healthy and many 

 of them soon developed their winter or resting buds. The seedlings in 

 the potting soil and in the nutrient solutions made good growth and did 

 not develop any buds until they had passed through the regular growing 

 period. Those grown in distilled water grew until the food contained in 

 the seed was exhausted, and then died. 



In this connection it was noted that the seedling growth the first season 

 was directly proportional to the size of the seed. This fact gives species 

 with large seeds an advantage over species with small seeds, for example, 

 yellow pine seedlings would become established on dry sites where hemlock 

 or cedar would fail. The yellow pine would be able to send down roots 

 to the moist soil, due to the food stored in the seed, while the small-seeded 

 species would have to depend on obtaining nourishment and moisture 

 from the surface soil, and consequently fail. Table I shows the results 

 of experiments with different depths of cover in loam soil to determine 

 the influence of food stored in the endosperm. 



