76 FORAGE PLANTS AND THEIR CULTURE 



In thrashing, these spores are scattered over the seeds, 

 and thus the young plants become infected. Among the 

 forage grasses thus subject to smut are the sorghums and 

 tall oat-grass. Treating the seeds by various different 

 methods will destroy the spores or prevent them from 

 germinating in time to infect the young seedlings. Such 

 methods are commonly used to prevent smut in such 

 grain crops as wheat, oats and sorghum, and probably 

 would be found efficient in such forage grasses as may be 

 similarly affected. 



71. Hard seeds. In many legumes some of the seeds 

 will not absorb water and germinate but remain hard. 

 The percentage of hard seeds varies with the seasonal or 

 other conditions under which it was grown. In the same 

 lot of seed the percentage of hard seed will gradually 

 diminish with age. Owing to the presence of such seeds, 

 red clover often shows a higher percentage of viability 

 when one year old than when fresh. 



American seed laboratories usually state the percentage 

 of hard seeds present in a sample. In Europe the practice 

 has been to consider a certain per cent of the hard seed 

 to be viable; namely, that which it is believed will ger- 

 minate in the soil under favorable conditions. 



The actual value of hard seed when sown in the field 

 needs to be determined for each species. It is certain 

 that some of it remains unsprouted in the ground at least 

 a year. 



Duvel buried " hard " seeds of red clover in porous 

 earthenware pots at depths of 6-8, 18-22 and 36-42 

 inches. At the end of 11 months the seeds germinated 

 respectively 10.5, 15.5 and 14.5 per cent. The hard seed 

 was selected by soaking seeds one year old in water for 

 18 hours and then for 20 hours, saving only those that 



