2 FIELD AND. LABORATORY STUDIES OF CROPS 



the cloth to project two inches beyond the upper edge of 

 the pane. Lay one of the sprouted grains on the cloth and 

 tie pieces of thread around the roots at intervals of one- 

 fourth inch, or^ if waterproof ink is available, mark the roots 

 with a fine pen instead of using the thread. Now place the 

 second pane of glass over the roots, with the upper edge just 

 below the seed, placing a slender piece of wood between the 

 panes to prevent crushing the plant. Fold the corners of 

 the cloth about the seed, put water into the pan to a depth 

 of half an inch, and set aside. After a day or two examine 

 the roots and note where the lengthening has occurred. 



The growth of the stems or branches of plants can be 

 studied in a similar manner by tying pieces of thread 

 around them at intervals of one-fourth inch, or by marking 

 them with ink. Measure carefully from time to time the 

 distance between the top mark and the tip of the plant, to 

 determine whether the entire stem elongates or the plant 

 makes its growth mainly at the tip. 



Discussion : This exercise shows the manner in which the 

 root elongates and pushes the soft, tender tip through the 

 soil. Is it not much easier for the roots to make their way 

 through a fine, mellow seed bed than through a hard soil? 

 How necessary it is, therefore, to have the soil well pulverized 

 and a deep, mellow seed bed prepared before the crop is 

 planted! 



Roots follow the line of least resistance, and if the sub- 

 soil is open and mellow the roots will penetrate deeper 

 than they otherwise would, thus increasing their feeding 

 zone. If the soil is mellow to the full depth, such crops 

 as beets and carrots will develop smooth, well-shaped roots. 



