4 BULLETIN 521^ V. S. DEPAETMENT OP AGEICULTUKE. 



OUTLINE FOR SOILS AND CROPS— FIRST YEAR. 

 (One unit.) 

 HOW PLANTS GROW. 



(Nine lessons, tliree double periods for practical work.) 



Reference : Any modern high-school text in botany. 

 Lesson 1. — Development of a Plant from the Seed. 



1. What the seed represents. 



2. Conditions essential to development. 



3. Vitality of seeds. 



4. Parts of seed and plantlet. 



5. Testing seeds. 



Illustrative material : Germinating seeds of different types. 



Exercise 1. — Germination Test of Seeds. 



Purpose: Testing for viability and to determine conditions essen- 

 tial to germination. 



Directions: Secure a quantity of wheat or any small hardy seed 

 known to be fresh, and another lot of the same kind of seed Imown 

 to be at least 10 years old. Have each student count out 50 to 100 

 seeds of each sample and place them in a plate between moistened 

 Canton flannel or blotting paper. With a slip of paper to designate 

 the sample, this seed should be covered with another plate or a piece 

 of glass to prevent too rapid evaporation of moisture. (Paper pie 

 plates, one within another, if kept moist, serve well Avithout blotters 

 or cloths. ) These plates of seeds should be kept in a warm room and 

 enough water added to keep the seeds moist but not wet. The class 

 as a whole should take three samples of the fresh seed, one to be kept 

 moist, but placed where it is cold ; the other two to be kept in a warm 

 place, but one lot kept covered with water to exclude air, and the 

 other allowed to become dry. At the end of six days the tests should 

 show results in a vigorous germination of the fresh seed kept warm 

 and moist and a lesser degree of vigor in the old seed and those sam- 

 ples deprived of warmth, moisture, and air. 



Record and report: Each student should make a record of how 

 the tests were made and write a report bringing out answers to the 

 following questions: Wliat per cent of the old and the fresh seed 

 germinated ? Why did the old seed lack vigor in germination ? Wliy 

 did the seed covered with water fail to germinate well? What 

 effect did the low temperature have upon the seeds? T^Hiat was the 

 effect of the lack of moisture? What conditions are essential to the 

 germination of seeds? Under what conditions should farm and gar- 

 den seeds be tested for viability? (Tables showing optimum, mini- 

 mum, and maximimi temperatures at which common seeds germi- 

 nate and the number of years various kinds of seeds remain viable 

 will prove helpful in connection with a study of germination.) 



