PHYSIOLOGY AND MINERAL NUTRITION 95 



Courtesy Florida Agricultural Experiment Station 



Figure 4. — Dixie Runner peanut plant which received a complete nutrient solution 

 in the rooting zone and a calcium-deficient solution in the fruiting zone (Plant 

 not grown same season as the ones in Figures 2 and 3). 



Bruner (17) studied root development of the peanut at different 

 stages of development when the plants were grown in a sandy loam soil 

 in Oklahoma. When the soil was removed carefully with little disturbance 

 of roots it was observed that the tap root of mature plants had a length 

 of about 3 feet and that 4 or more rows of lateral roots grew horizontally" 

 for several inches and then downward for a distance of 2 or more feet. 

 In general, branch roots were perpendicular to the main roots. Numerous 

 temporary roots, designated as absorbing rootlets, were present on all 

 roots of the permanent system. Such rootlets either deteriorated with 

 age or developed into permanent roots. All young branch roots were 

 considered absorptive rootlets. During early stages of plant growth the 

 absorbing rootlets developed prominently in the first foot of soil, but 

 later the subsoil became progressively more and more filled with them. 



In India (58) a similar experiment was conducted using Burmese, a 

 runner type, and Small Japan and Small Spanish, bunch types, with 

 results shown in table 3. These data indicate that the extensive root 

 system of the peanut might penetrate the soil to a depth of 6 feet. 



