Aug. 14, 1916 Agricultural Value 0} Impermeable Seeds 775 



2 . An average of 69 per cent of the impermeable alfalfa seeds produced 

 seedlings in one month, and an average of 80 per cent in two months, 

 after which only one new seedling appeared in the next four months. 



3. Thirty-eight per cent of the one lot of impermeable hairy-vetch 

 seeds produced seedlings in one month, after which no new seedlings 

 appeared. 



4. It is worthy of notice that after four months, during which no new 

 sweet-clover seedlings appeared, 10 per cent of the seeds used produced 

 seedlings in a few days following the cold weather in November. This 

 is particularly interesting in the light of subsequent results. 



EFFECT OF DIFFERENT CONDITIONS UPON THE GERMINATION OP IMPER- 

 MEABLE SEEDS IN SOIL 



It has been shown that some seeds which would be reported as imper- 

 meable according to the chamber tests will produce seedlings in a com- 

 paratively short time in the soil. Experiments were conducted to deter- 

 mine the effects of separate factors. 



Comparative tests showed that neither moistening the blotters which 

 were used for germinating bed with strong aqueous soil extracts nor the 

 alternate wetting and drying of the seeds at frequent intervals affects the 

 rate of softening of impermeable clover seeds. 



Neither the depth of planting nor the firmness of the soil nor the con- 

 servation of surface moisture by shading affected the precentage of seed- 

 ling production by impermeable clover and alfalfa seeds in greenhouse 

 tests, except when the seeds were planted over % inch deep. Fewer seed- 

 lings reached the surface of the soil from seeds planted 1 inch deep than 

 from seeds planted X to % inch deep. 



On the other hand, certain factors influenced the softening of im- 

 permeable seeds and would probably affect the production of seedlings in 

 the soil. These factors will be considered in the following sections. 



EFFECT OF HIGH TEMPERATURES UPON THE GERMINATION OF IMPERMEABLE CLOVER 



AND ALFALFA SEEDS 



Dry heating. — Storing seeds for 6 months in a dry atmosphere at 

 45 C. slightly increased the subsequent germination of previously imper- 

 meable alfalfa seeds, but had no effect upon impermeable seeds of red 

 clover or sweet clover. These results differ from results obtained by 

 Hiltner (11). This author found that drying red-clover seed for eight days 

 at 35 slightly increased both the percentage which remained hard after 

 a 10-day germination test and the percentage which softened but did not 

 germinate. 



Heating at 50 C. for 2 1 hours had no effect upon the softening or ger- 

 mination of impermeable seeds of red clover or sweet clover when later 

 subjected to a germination test. 



