SEED CHARACTERISTICS IN CONIFEROUS FORESTS 21 



Commercial sulphuric acid chars the seed-coats as soon as the seed is 

 immersed. Where the seeds were left for thirty minutes and more in the 

 full strength acid, the seed-coats could all be removed by slightly rubbing 

 the seed, thus leaving the endosperm naked. Even in this condition, the 

 viability of the seed was unimpaired, and, as the table shows, the strongest 

 treatment gave the best germination results. 



Seed treated with half strength acid showed no appreciable effects 

 upon the seeds or on the germination. 



Germination in all of the plots was perfectly normal. Seedlings in all 

 the treatments appeared healthy and thrifty. Seedlings in the plots 

 treated with the full strength acid for the longer periods appeared above 

 ground, bringing up the endosperm without the seed-coat, and in some 

 cases the cotyledons grew out through the sides of the endosperm. Seed- 

 lings appearing in this way produced strong, vigorous plants however. 



Seed that was soaked in C. P. sulphuric acid for one hour was covered 

 with water after the acid was poured off. The reaction created a tempera- 

 ture of 168 F. The exocarp was charred and most of it destroyed by 

 the acid. The mesocarp and endocarp were also charred so that they 

 rubbed off easily, but the endosperm or food material of the seed was 

 apparently uninjured. Some of the seed germinated. Seed soaked for 

 more than one hour and treated with water failed to germinate. 



Aside from the experiments made to test out what severe conditions 

 seeds will withstand and still retain their viability, the following chemical 

 experiments to determine influence on germination were done with the same 

 species, Pinus monticola. 



Copper sulphate. Ten treatments, varying from one part copper 

 sulphate to one part of water by weight, up to one part copper sulphate 

 to five and one-half parts of water, showed that germination was stimulated 

 by the chemical. The seed-coats opened in a few days, but as soon as 

 they separated the copper sulphate solution stained and killed the germi- 

 nating seed. 



Copper acetate. Ten treatments, varying from one part copper acetate 

 to one part water by weight, to one part copper acetate to five and one-half 

 parts of water, showed that germination was stimulated by the copper 

 acetate, but the growing tips were killed as soon as they appeared. Chemi- 

 cal injury occurred in all of the strengths used. In the weaker treatments, 

 the germinating tips were stained blue, and in the stronger treatments 

 the entire endosperm and plumule were stained blue. 



The above experiments show that the seed in the dormant state will with- 

 stand very severe conditions, but is quite easily killed after germination 

 begins. The chemical condition of the forest floor may therefore influence 

 the viability of the seed and also be a major factor in determining the length 

 of the period through which the seed will lie dormant and retain its viability. 



