Chapter Three 

 GERMINATION OF SEEDS 



The optimum conditions for germination vary for differ- 

 ent species of seeds, but even for a given species of seeds the 

 conditions may vary over a wide range, as described later 

 under soil moisture and temperature. The gardener always 

 strives to reach the optimum for each kind of seed. After 

 selecting good seeds, the following should always be con- 

 sidered: the best moisture condition, the best temperature, 

 and adequate air for the oxygen supply. 



The seed must absorb a large amount of moisture, often 

 double its dry weight. A soil which is so dry that it supplies 

 water to the seeds more slowly than a moist soil, retards their 

 germination. Since most seed coats are permeable to water 

 on all surfaces they should have the moist soil pressed tightly 

 against them at all points when they are planted. For this 

 reason the gardener often walks on the planted row. Other 

 methods of compacting the soil are: tamping with a hoe or 

 board, or with a horse-drawn roller. 



Soaking seeds in water before planting is not only unnec- 

 essary but actually may be harmful in that it reduces the 

 germination vigor because of the loss of mineral salts to the 

 water and the lack of oxygen which is essential for respira- 

 tion. Water is absorbed by seeds with so great a force that 

 it is readily taken from soil. If a thin-walled glass bottle is 

 filled with dry peas and water is added, they will absorb the 

 water and swell with a force great enough to break the bottle. 

 Other experiments have shown that water enters dry seeds 

 against a force of several hundred pounds per square inch 

 when they are in soil with less than the optimum water con- 

 tent. This accounts for the rapid and advantageous absorp- 

 tion direct from the soil. 



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