WHAT GERMINATION IS 8 



If there is not enough moisture to cause the seeds to take up water 

 rapidly they will remain dormant for a long time in the soil. As 

 many seeds are planted very shallow, and as the top layer of soil 

 is usually drier than that farther down, their germination is often 

 very slow. It may be hastened by increasing the moisture in 

 some way. This may be done by watering the seed bed or by firm- 

 ing the soil. 



If the moist soil be pressed firmly against the seeds water will be 

 absorbed and germination take place sooner than if the soil is left 

 very loose. It is for this reason that seed beds are rolled. The 

 gardener may tramp upon the row of seeds after he has planted it. 



Warmth. The needs for proper temperature for germination 

 are usually well understood by the farmer or gardener. It is pos- 

 sible for him to control the temperature of the soil to a very great 

 extent. Harrowing will warm the soil by letting in warm air. 

 Rolling in the spring cools it by increasing the evaporation. He 

 also knows that certain kinds of seed will start when the soil is 

 comparatively cool, while others must not be planted until later 

 when the air and soil have become very warm. Oats will not 

 sprout well at a temperature below 40 degrees F., and prefer a 

 temperature of 60 degrees or more. Corn needs about 50, and will 

 do better if the soil is as warm as 80 or 90 degrees. 



Air and Oxygen. Air is usually present in soils in sufficient 

 abundance to allow seeds to germinate properly. This is par- 

 ticularly true of coarse or sandy soils. In heavy clay there may 

 be enough water present to exclude the air. If the air be kept 

 out because the soil is puddled or too firmly packed when wet, 

 germination is not likely to take place. Seeds differ a great deal 

 in this matter. Flax for example does not require so much air 

 for germination as wheat or corn. It is partly because of these 

 differences in seeds that the cultural methods are found to vary 

 so widely. The student may prove the need of air for germina- 

 tion by placing seeds of any kind in a bottle of water to see if they 

 will germinate. They should be compared with others placed in 

 proper conditions of moisture, warmth and air. 



What Germination Is. When seeds begin to germinate the store 

 of plant food in them is changed into a form suitable for circulation 

 (Fig. 2) . As moisture is absorbed and oxygen taken in, carbon diox- 

 ide is given off. During these changes the tissues of the embry- 

 onic plant contained in the seed begin to grow. Soon a stem is 

 formed which turns its growing joint downward and away from the 



