eH. ix] Valuation and Purchase of Grass Seeds 165 



may have suffered from exposure during harvesting or through 

 faulty storage. Or again it may have been kept over for one or 

 more seasons and so have lost some of its original germinating 

 power. At the same time the difference in colour and general 

 appearance between such seed and that which is practically per- 

 fect may be so slight, that only those accustomed to constantly 

 handling seeds might have any suspicion about it. It is therefore 

 of the highest importance to have the germination tested. 



At properly equipped seed-testing stations the germination of 

 the pure seed is usually determined on four lots of 100 seeds 

 each in suitable germinating dishes, placed either in a greenhouse 

 or specially ventilated incubator, and under suitable conditions 

 as regards temperature and moisture supply. A temperature of 

 about 20° C. is most suitable for the Rye-grasses, Oat-grasses, 

 Meadow Foxtail, and Timothy. For the Fescues, Cock's-foot, 

 •Crested Dog's-tail and most other common species a temperature 

 of from 20°-23° C. gives the best results. Such tests should 

 extend over a period of 14 days for Rye-grasses and Timothy; 

 for 28 days in the case of Poa pratensis, Poa nemoralis, and 

 Agrostis sps. ; and for 21 days for most other kinds. It should 

 be understood, however, that the tests in the case of good samples 

 may often be concluded in somewhat less than the times here 

 given. The germination to be expected of good samples under 

 the above conditions is stated in Chap. vni. 



4. Germination Speed or Energy is the rate at which the 

 pure seed germinates. Rapid, vigorous germination indicates 

 new, well-matured, healthy seed, while a slow germination is 

 typical of the reverse conditions. To indicate the relative vigour 

 or energy of a sample it is customary to give the percentage of 

 growth made in about one-fourth the time allowed for a full test. 

 For Timothy three days should be allowed; for Rye-grasses, 

 Meadow Fescue, and Tall Oat-grass four or five days ; and for 

 most other grasses seven days. 



5. Absolute Weight and Bushel Weight. When grass seeds are 

 very thoroughly cleaned not only are most of the weed impurities 

 and chaffy materials removed, but also a large proportion of the 

 half-filled and immature seeds are taken out. A thousand pure 

 seeds of such a sample will weigh more* than a thousand taken 



