330 Journal of Agricultural Research voi. vi, ko. 9 



The relation of the weight of the dry matter of the aerial portions of 

 mature plants to the weight of the roots was determined in 1914 for 

 36 Dwarf milo plants, 30 Blackhull kafir plants, and 12 corn plants. 

 In 1 91 5 the same determinations were made for 24 Dwarf milo plants, 

 14 Dwarf Blackhull kafir plants, 23 Blackhull kafir plants, and 24 corn 

 plants. 



The average ratio of the dry weight of the grain, stem, and leaves of 

 standard kafir to the dry weight of the roots was found to be 15 and 14.9 

 for the years 1914 and 191 5, respectively, while the dry weight of the 

 stem and leaves of the same plant was on the average 10.9 times that of 

 the root weight in 1914 and lo.i times the root weight in 1915. The 

 ratio of the dry weight of the stem, leaves, and grain of Dwarf milo to 

 the weight of the roots was found to be as 15.7 to i in 1914, and as 15 to 

 I in 1 91 5, and the weight of the stem and leaves of the same plants was 

 9.6 and 8 times, respectively, the weight of the roots in 1914 and 1915. 

 The weight of the stem and leaves of Pride of vSaline com was 9.6 times 

 the root weight in 1914, while in 191 5 the weight of the stem and leaves 

 of the com was 7.8 times the weight of the root system. The aerial parts 

 of Dwarf Blackhull kafir examined in 191 5 showed a weight 15.7 times 

 that of the roots, while the weight of the stem and leaves amounted to 

 8.9 times the weight of the underground portion. 



The results of the experiments for the two years in regard to the soil- 

 moisture content and depth of root penetration seem to show that under 

 the conditions of this experiment very little, if any, depletion of soil 

 moisture took place below the depth of root penetration. 



The average leaf areas of five representative plants of corn, Blackhull 

 kafir, and Dwarf milo were obtained at stages when the plants were 4, 

 6, 8, and 10 weeks of age. The last stage examined showed that the 

 plants had completed their full-leaf development. In all the stages of 

 growth the com plant was found to have the greatest leaf area. Taking 

 the stages of growth in order, one finds that the leaf area of the com 

 plant w^as 1.7, 2.0, 2.2, and 2.3 times the leaf area of Dwarf milo and 1.6, 

 1.9, 1.5, and 1.5 times that of Blackhull kafir. 



In comparing the plants of Dwarf milo, Blackhull kafir, and Pride 

 of Saline com, it will be seen that in all stages of their growth these 

 two sorghum plants have a primary root system that is just as 

 extensive as that of the corn plant. In addition, the Dwarf milo and 

 Blackhull kafir possess twice as many secondary roots as the com at any 

 stage of its growth. The leaf area of the corn plant at all stages of its 

 growth is approximately twice as great as that of the Dwarf milo and 

 never less than 1.5 times that of Blackhull kafir. 



It is apparent, therefore, that the Dwarf milo and Blackhull kafir plants 

 would have the advantage over the corn plant under any climatic con- 

 dition that would tend to bring about a loss of water from these plants. 



