PLANT IMPROVEMENT, GOOD SEED 25 



EXERCISE. Identifying Weed Seeds. The figures in 

 U. S. Farmers' Bulletins 260 and 382 will help to determine 

 the names of the weed seeds not known by the pupils. Let 

 students cut out the figures and paste them on a card for 

 quick reference. If the school has a collection of weed seeds 

 in small bottles (Fig. 15), they may now be used to help 

 identify the unknown seeds. 



EXERCISE. To Compare Good and Poor Lots of Grass 

 Seeds. Take a piece of clean window glass and wet it with 

 water. Spread on it a thin layer of blue-grass or of red-top 

 seeds. Hold the glass between you and the bright light. 

 Notice how many of the glumes or husks are hollow. Com- 

 pare in this way a good sample with a poor one. Note the 

 difference in the amount of chaff. 



Seed Analysis. The methods of studying seeds outlined 

 in two preceding exercises may be called seed analysis. The 

 sieves mentioned before may also be used in analyzing a 

 sample of seed as well as in aiding in the cleaning of large 

 quantities. 



Seed Testing. Another way to detect impurities in 

 seeds is by sprouting a sample of the seed and then observ- 

 ing the differences in character of growth; they may differ 

 in the shape or number of seed leaves, or in manner of coming 

 out of the seed coats. 



Another reason for seed testing is to determine the 

 vitality or germinating power of the sample. 



There are several advantages of knowing the vitality: 



1. It will save us buying poor seed if we test a sample 

 before buying. 



2. If the test is low we will not use the seed at all, even 

 if we own it. 



3. If it is as good as we can get we will plant enough more 

 seed than usual to allow for the reduced vitality. 



4. Thus knowing how much to plant, will save us the 

 time, labor, and expense of replanting a crop after the first 

 planting shows a poor stand. 



