138 



AGRONOMY 



their vitality longer than oily ones. There is no truth, how- 

 ever, in the idea that seeds thousands of years old, found in 

 the pyramids or dug out of Indian graves, will grow. Weed 

 seeds are especially persistent, but few of them can grow after 

 twenty years. In some seeds the age seems to affect the crop, 

 fresh seeds producing more vigorous plants with a tendency 

 to put forth leaves and stems only, while older ones are likely 

 to be more fruitful. Growers of melons prefer seeds several 

 years old for this reason. 



Seed testing. When a crop is planted upon which much 

 depends, or when for any reason there is doubt about the seeds 

 being good, it is customary to test them before planting. A 



A B 



Fi<;. 99. A seed tester, consisting of two soup plates, some sand, and a 



piece of cloth 



serviceable seed tester may be made of a dinner plate, a sheet 

 of glass, and two pieces of rather thick cloth cut to fit the plate. 

 The cloths are dipped in water, the excess moisture wrung 

 out, and the seeds to be germinated placed between them. 

 The cloths are placed on the plate and covered with the glass 

 or another plate to keep in the moisture, and the apparatus 

 set away in a warm place. From time to time the seeds are 

 examined and those which have germinated removed. By this 

 means one may very quickly discover what proportion of a 

 given lot of seeds is viable. Wet sand may be used in place 

 of the cloth in the seed tester, if desired. 



Double cropping. Different crops vary greatly in the time 

 taken to mature. Long-season crops, such as salsify and pars- 

 nips, are planted early in spring, occupy the ground until frost, 



